 Chapter 20 Part 2 of THE VOYAGE OF THE BEGLE A few miles north of Kiela, there is another small atoll, the lagoon of which is nearly filled up with coral mud. Captain Ross found embedded in the conglomerate on the outer coast a well-rounded fragment of greenstone, rather larger than a man's head. He and the men with him were so much surprised at this that they brought it away and preserved it as a curiosity. The occurrence of this one stone where every other particle of matter is calcareous certainly is very puzzling. The island has scarcely ever been visited, nor is it probable that a ship had been wrecked there. From the absence of any better explanation I came to the conclusion that it must have come entangled in the roots of some large tree. When, however, I considered the great distance from the nearest land, the combination of chances against a stone thus being entangled, the tree washed into the sea, floated so far, then landed safely, and the stone finally so embedded as to allow its discovery I was almost afraid of imagining a means of transport, apparently so improbable. It was therefore with great interest that I found Chamiso, the justly distinguished naturalist who accompanied Katsubu, stating that the inhabitants of the Radak Archipelago, a group of lagoon islands in the midst of the Pacific, obtained stones for sharpening their instruments by searching the roots of trees which are cast upon the beach. It will be evident that this must have happened several times, since laws have been established that such stones belong to the chief, and a punishment is inflicted on anyone who attempts to steal them. When the isolated position of these small islands in the midst of a vast ocean, their great distance from any land, accepting that of coral formation, attested by the value which the inhabitants, who are such bold navigators, attach to a stone of any kind, footnote 7, some natives carried by Katsubu to Kamchakka, collected stones to take back to their country. And the slowness of the currents of the open sea are all considered, the occurrence of pebbles thus transported does appear wonderful. Stones may often be thus carried, and if the island on which they are stranded is constructed of any other substance besides coral, they would scarcely attract attention, and their origin at least would never be guessed. Moreover, this agency may long escape discovery from the probability of trees, especially those loaded with stones, floating beneath the surface. In the channels of Tierra del Fuego, large quantities of drift timber are cast upon the beach, yet it is extremely rare to meet a tree swimming on the water. These facts may possibly throw light on single stones, whether angular or rounded, occasionally found embedded in fine sedimentary masses. During another day, I visited West Islet, on which the vegetation was perhaps more luxuriant than on any other. The coconut trees generally grow separate, but here the young ones flourished beneath their tall parents and formed with their long and curved fronds the most shady arbors. Those alone who have tried it know how delicious it is to be seated in such shade and drink the cool, pleasant fluid of the coconut. In this island there is a large bay-like space composed of the finest white sand. It is quite level and is only covered by the tide at high water. From this large bay, smaller creeks penetrate the surrounding woods. To see a field of glittering white sand representing water, with the coconut trees extending their tall and waving trunks around the margin, formed a singular and very pretty view. I had before alluded to a crab which lives on the coconuts. It is very common on all parts of the dry land and grows to a monstrous size. It is closely allied to, or identical with, the beer-ghost latro. The front pair of legs terminate him very strong and heavy pincers, and the last pair are fitted with others weaker and much narrower. It would at first be thought quite impossible for a crab to open a strong coconut covered with the husk, but Mr. Leek assures me that he has repeatedly seen this affected. The crab begins by tearing the husk, fiber by fiber, and always from that end under which the three eye holes are situated. When this is completed, the crab commences hammering with its heavy claws on one of the eye holes till an opening is made. Then, turning round its body by the aid of its posterior and narrow pair of pincers, it extracts the white, albuminous substance. I think this is as curious a case of instinct as ever I heard of, and likewise of adaptation and structure between two objects apparently so remote from each other in the scheme of nature as a crab and a coconut tree. The beer-ghost is diurnal in its habits, but every night it is said to pay a visit to the sea, no doubt for the purpose of moistening its branchier. The young are likewise hatched and live for some time on the coast. These crabs inhabit deep burrows, which they hollow out beneath the roots of trees, and where they accumulate surprising quantities of the picked fibers of the coconut husk, on which they rest as on a bed. The malaise sometimes take advantage of this and collect the fibrous mass to use as junk. These crabs are very good to eat, moreover, under the tail of the larger ones there is a mass of fat which, when melted, sometimes yields as much as a quart bottle full of limpid oil. It has been stated by some authors that the beer-ghost crawls up the coconut trees for the purpose of stealing the nuts. I very much doubt the probability of this, but with the pandanus, footnote 8, sea proceedings of Zoological Society, 1832, page 17, the task would be very much easier. I was told by Mr. Liske that on these islands the beer-ghost lives only on the nuts which have fallen to the ground. Captain Moresby informs me that this crab inhabits the Chagos and Seychelles groups, but not the neighboring Maldiva archipelago. It formerly abounded at Mauritius, but only a few small ones are now found there. In the Pacific, this species, or one with closely allied habits, is said to inhabit a single coral island north of the society group. Footnote 9, Tyerman and Bennett, Voyages, et cetera, volume 2, page 33. To show the wonderful strength of the front pair of pincers, I may mention that Captain Moresby confined one in a strong tin box which had held biscuits, the lid being secured with wire, but the crab turned down the edges and escaped. In turning down the edges, it actually punched many small holes quite through the tin. I was a good deal surprised by finding two species of coral of the genus Milipora, M. Complanata and Ausicornis. Possess the power of stinging. The stony branches or plates, when taken fresh from the water, have a harsh feel and are not slimy, although possessing a strong and disagreeable smell. The stinging property seems to vary in different specimens. When a piece was pressed or rubbed on the tender skin of the face or arm, a pricking sensation was usually caused, which came on after the interval of a second and lasted only for a few minutes. One day, however, by merely touching my face with one of the branches, pain was instantaneously caused. It increased as usual after a few seconds and remained sharp for some minutes, was perceptible for half an hour afterwards. The sensation was as bad as that from a nettle, but more like that caused by the Fasalia or Portuguese man of war. Little red spots were produced on the tender skin of the arm, which appeared as if they would have formed watery pustules, but did not. M. Coy mentions this case of the Milipora, and I have heard of stinging corals in the West Indies. Many marine animals seem to have this power of stinging. Besides the Portuguese man of war, many jellyfish and the aplasia or sea slug of the Cap de Verde Islands. It is stated in the voyage of the Astrolab that an actinia or sea anemone, as well as a flexible coraline, allied to sertularia, both possess this means of offense or defense. In the East Indian Sea, a stinging seaweed is said to be found. Two species of fish of the genus Scarus, which are common here, exclusively feed on coral. Both are colored of a splendid bluish green, one living invariably in the lagoon, and the other amongst the outer breakers. M. Lisca assured us that he had repeatedly seen whole shoals grazing with their strong bony jaws on the tops of the coral branches. I opened the intestines of several, and found them distended with yellow calcareous sandy mud. The slimy, disgusting holothurrier, allied to our starfish, which the Chinese gourmands are so fond of, also feed largely, as I am informed by Dr. Allen, on corals, and the bony apparatus within their bodies seems well adapted for this end. These holothurrier, the fish, the numerous burrowing shells, and neuratus worms, which perforate every block of dead coral, must be very efficient agents in producing the fine white mud, which lies at the bottom and on the shores of the lagoon. A portion, however, of this mud, which when wet resembled pounded chalk, was found by Professor Ehrenberg to be partly composed of Silicius shielded infusoria. April 12. In the morning we stood out of the lagoon on our passage to the Isle of France. I am glad we have visited these islands. Such formations surely rank high amongst the wonderful objects of this world. Captain Fitzroy found no bottom with a line 7,200 feet in length, at the distance of only 2,200 yards from the shore, hence this island forms a lofty submarine mountain, the side steeper even than those of the most abrupt volcanic cone. The saucer-shaped summit is nearly 10 miles across, and every single atom, from the least particle to the largest fragment of rock in this great pile, which, however, is small compared with very many other lagoon islands, bears the stamp of having been subjected to organic arrangement. Footnote 10. I exclude, of course, some soil which has been imported here in vessels from Malacca and Java, and likewise some small fragments of pumice drifted here by the waves. The one block of greenstone, moreover, on the northern island, must be accepted. We feel surprised when travelers tell us of the vast dimensions of the pyramids and other great ruins, but how utterly insignificant are the greatest of these when compared to these mountains of stone accumulated by the agency of various minute and tender animals. This is a wonder which does not at first strike the eye of the body, but after reflection, the eye of reason. I will now give a very brief account of the three great classes of coral reefs, namely atolls, barrier, and fringing reefs, and will explain my views on their formation. Footnote 11. These were first read before the geological society in May 1837, and have since been developed in a separate volume on the structure and distribution of coral reefs. Almost every voyager who has crossed the Pacific has expressed his unbounded astonishment at the lagoon islands, or, as I shall for the future, call them by their Indian name of atolls, and has attempted some explanation. Footnote 11. Even as long as Go is the year 1605, Pirar de Laval well exclaimed, C'est un merveille de voir chacun de ces atolls, And l'Iron de un grand banc de pied tout autour, Ni un point d'artifice humain. The accompanying sketch of Whitsunday Island in the Pacific, copied from Captain Beachy's admirable voyage, gives but a faint idea of the singular aspect of an atoll. It is one of the smallest size and has its narrow islets united together in a ring. The immensity of the ocean, the fury of the breakers, contrasted with the lowness of the land, and the smoothness of the bright green water within the lagoon, can hardly be imagined without having been seen. The earlier voyagers fancied that the coral-building animals instinctively built up their great circles to afford themselves protection in the inner parts, but so far as this from the truth that those massive kinds to whose growth on the exposed outer shores the very existence of the reef depends cannot live within the lagoon, where other delicately branching kinds flourish. Moreover, on this view, many species of distinct genera and families are supposed to combine for one end, and of such a combination, not a single instance can be found in the whole of nature. The theory that it's been most generally received is that the atolls are based on submarine craters, but when we consider the form and size of some, the number, proximity, and relative positions of others, this idea loses its plausible character. Thus, Suadiva atoll is 44 geographical miles in diameter in one line, by 34 miles in another line. Rimsky is 54 by 20 miles across, and it has a strangely sinuous margin. Bow atoll is 30 miles long, and on an average only six in width. Menchikov atoll consists of three atolls, united or tied together. This theory moreover is totally inapplicable to the northern Maldiva atolls in the Indian Ocean, one of which is 88 miles in length and between 10 and 20 in breadth, for they are not bounded like ordinary atolls by narrow reefs, but by a vast number of separate little atolls, other little atolls rising out of the great central lagoon-like spaces. A third and better theory was advanced by Chamiso, who thought that from the corals growing more vigorously were exposed to the open sea, as undoubtedly is the case, the outer edges would grow up from the general foundation before any other part, and that this would account for the ring or cup-shaped structure, but we shall immediately see that in this, as well as in the crater theory, a most important consideration has been overlooked, namely on what have the reef-building corals, which cannot live at a great depth, based their massive structures. Numerous soundings were carefully taken by Captain Fitzroy on the steep outside of Keeling atoll, and was found that within ten fathoms the prepared tallow at the bottom of the lead invariably came up marked with the impression of living corals, but as perfectly clean as if it had been dropped on a carpet of turf. As the depth increased, the impressions became less numerous, but the adhering particles of sand more and more numerous, until at last it was evident that the bottom consisted of a smooth, sandy layer. To carry on the analogy of the turf, the blades of grass grew thinner and thinner, till at last the soil was so sterile that nothing sprang from it. From these observations, confirmed by many others, it may be safely inferred that the utmost depth at which corals can construct reefs is between 20 and 30 fathoms. Now, there are enormous areas in the Pacific and Indian Ocean in which every single island is of coral formation, and is raised only to that height to which the waves can throw up fragments and the winds pile up sand. Thus, Radak group of atolls is an irregular square, 520 miles long and 240 broad. The low archipelago is elliptic formed, 840 miles in its longer and 420 in its shorter axis. There are other small groups and single low islands between these two archipelagos, making a linear space of ocean actually more than 4,000 miles in length, in which not one single island rises above the specified height. Again, in the Indian Ocean, there is a space of ocean 1500 miles in length, including three archipelagos in which every island is low and of coral formation. From the fact of the reef building corals not living at great depths, it is absolutely certain that throughout these vast areas, wherever there is now an atoll, a foundation must have originally existed within a depth from 20 to 30 fathoms from the surface. It is improbable in the highest degree that broad, lofty, isolated, steep-sided banks of sediment, arranged in groups and lines, hundreds of leagues and length, could have been deposited in the central and profoundest parts of the Pacific and Indian Oceans, at an immense distance from any continent and where the water is perfectly limpid. It is equally improbable that the elevatory forces should have uplifted throughout the above vast areas innumerable great rocky banks within 20 to 30 fathoms, or 120 to 180 feet, of the surface of the sea, and not one single point above that level. For where on the whole surface of the globe can we find a single chain of mountains, even a few hundred miles in length, with their many summits rising within a few feet of a given level, and not one pinnacle above it. If then the foundations, whence the atoll-building corals sprang, were not formed of sediment, and if they were not lifted up to the required level, they must of necessity have subsided into it. And this at once solves the difficulty, for as mountain after mountain and island after island slowly sank beneath the water, fresh bases would be successively afforded for the growth of the corals. It is impossible here to enter into all the necessary details, but I venture to defy anyone to explain in any other manner how it is possible that numerous islands should be distributed throughout vast areas, all the islands being low, all being built of corals, absolutely requiring a foundation within a limited depth from the surface. Footnote 12. It is remarkable that Mr. Lyle, even in his first edition of his Principles of Geology, inferred that the amount of subsidence in the Pacific must have exceeded that of elevation, from the area of land being very small, relatively to the agents there tending to form it, namely the growth of coral and volcanic action. Before explaining how atoll-formed reefs acquire their peculiar structure, we must turn to the second great class, namely barrier reefs. These either extend in straight lines in front of the shores of a continent or of a large island, or they encircle smaller islands, in both cases being separated from the land by a broad and rather deep channel of water, analogous to the lagoon within an atoll. It is remarkable how little attention has been paid to encircling barrier reefs, yet they are truly wonderful structures. The following sketch represents part of the barrier encircling the island of Bola Bola in the Pacific, as seen from one of the central peaks. In this instance, the whole line of reef has been converted into land, but usually a snow-white line of great breakers, with only here and there a single low islet crowned with coconut trees divides the dark heaving waters of the ocean from the light green expanse of the lagoon channel. And the quiet waters of this channel generally bathe a fringe of low alluvial soil, loaded with the most beautiful productions of the tropics, and lying at the foot of the wild, abrupt central mountains. Encircling barrier reefs are of all sizes, from 3 miles to no less than 44 miles in diameter, and that which fronts one side and encircles both ends of New Caledonia is 400 miles long. Each reef includes one, two, or several rocky islands of various heights, and in one instance, even as many as 12 separate islands. The reef runs at a greater or lesser distance from the included land, in the society archipelago generally from 1 to 3 or 4 miles, but at Hogolio the reef is 20 miles on the southern side and 14 miles on the opposite or northern side from the included islands. The depth within the lagoon channel also varies much, from 10 to 30 fathoms, maybe taken as an average, but at Vanicoro there are spaces no less than 56 fathoms, or 363 feet deep. Internally the reef either slopes gently into the lagoon channel, or ends in a perpendicular wall, sometimes between 2 and 300 feet underwater in height. Externally the reef rises, like an atoll, with extreme abruptness out of the profound depths of the ocean. What can be more singular than these structures? We see an island which may be compared to a castle situated on the summit of a lofty submarine mountain, protected by a great wall of coral rock, always steep externally and sometimes internally, with a broad level summit, here and there breached by a narrow gateway through which the largest ships can enter the wide and deep encircling moat. As far as the actual reef of coral is concerned there is not the smallest difference in general size, outline, grouping, and even in quite trifling details of structure between a barrier and an atoll. The geographer Balby has well remarked that an encircled island is an atoll with high land rising out of its lagoon, remove the land from within and a perfect atoll is left. But what has caused these reefs to spring up at such great distances from the shores of the included islands? It cannot be that the corals will not grow close to the land, for the shores within the lagoon channel, when not surrounded by alluvial soil, are often fringed by living reefs. And we shall presently see that there is a whole class, which I have called fringing reefs from their close attachment to the shores both of continents and of islands. Again on what have the reef building corals which cannot live at great depths based their encircling structures. This is a great apparent difficulty, analogous to that in the case of atolls, which has generally been overlooked. It will be perceived more clearly by inspecting the following sections, which are real ones, taken in north and south lines through the islands with their barrier reefs of Vanakoro, Gambier and Mau Rua. And they are laid down both vertically and horizontally on the same scale of a quarter of an inch to a mile. It should be observed that these sections might have been taken in any direction through these islands or through many other encircled islands, and the general features would have been the same. Now bearing in mind that the reef building coral cannot live at a greater depth than from 20 to 30 fathoms, and that the scale is so small that the plummets on the right hand show a depth of 200 fathoms on what are these barrier reef spaced. Are we to suppose that each island is surrounded by a color-like submarine ledge of rock or by a great bank of sediment ending abruptly where the reef ends? If the sea had formerly eaten deeply into the islands before they were protected by the reefs, thus having left a shallow ledge round them underwater, the present shores would have been invariably bounded by great precipices, but this is most rarely the case. Moreover on this notion, it is not possible to explain why the coral should have sprung up like a wall from the extreme outer margin of the ledge, often leaving a broad space of water within, too deep for the growth of corals. The accumulation of a wide bank of sediment all around these islands, and generally widest where the included islands are smallest, is highly improbable considering their exposed positions in the central and deepest parts of the ocean. In the case of the barrier reef of New Caledonia, which extends for 150 miles beyond the northern point of the islands in the same straight line with which it fronts the west coast, it is hardly possible to believe that a bank of sediment could thus have been straightly deposited in front of a lofty island and so far beyond its termination in the open sea. Finally, if we look to other oceanic islands of about the same height and of similar geological constitution but not encircled by coral reefs, we may in vain search for so trifling a circumambient depth as 300 fathoms except quite near to their shores, for usually land that rises abruptly out of water, as do most of the encircled and non-encircled oceanic islands, plunges abruptly under it. On what then, I repeat, are these barrier reefs based? Why, with their wide and deep moat-like channels, do they stand so far from the included land? We shall soon see how easily these difficulties disappear. We come now to our third class of fringing reefs, which will require a very short notice, where the land slopes abruptly underwater, these reefs are only a few yards in width, forming a mere ribbon or fringe round the shores. Where the land slopes gently under the water, the reef extends further, sometimes even as much as a mile from the land, but in such cases the soundings outside the reef always show that the submarine prolongation of the land is gently inclined. In fact, the reefs extend only to that distance from the shore, at which a foundation within the requisite depth from 20 to 30 fathoms is found. As far as the actual reef is concerned, there is no essential difference between it and that forming a barrier or an atoll. It is, however, generally of less width, and consequently few islets have been formed on it. From the corals growing more vigorously on the outside and from the noxious effect of the sediment washed inwards, the outer edge of the reef is the highest part, and between it and the land there is generally a shallow sandy channel a few feet in depth. Where banks or sediments have accumulated near to the surface, as in parts of the West Indies, they sometimes become fringed with corals, and hence in some degree resemble lagoon islands or atolls in the same manner as fringing reefs surrounding gently sloping islands in some degree resemble barrier reefs. Joseph Eugarets The Voyage of the Beagle by Charles Darwin Chapter 20 Part 3 Keeling Island Coral Formations No theory on the formation of coral reefs can be considered satisfactory, which does not include the three great classes. We have seen that we are driven to believe in the subsidence of those vast areas interspersed with low islands, of which not one rises above the height to which the wind and waves can throw a matter, and yet are constructed by animals requiring a foundation, and that foundation to lie at no great depth. Let us then take an island surrounded by fringing reefs, which offer no difficulty in their structure, and let this island with its reefs, represented by the unbroken lines in the woodcut, slowly subside. Now, as the island sinks down, either a few feet at a time, or quite insensibly, we may safely infer from what is known of the conditions favorable to the growth of coral that the living masses bathed by the surf on the margin of the reef will soon regain the surface. The water, however, will encroach little by little on the shore, the island becoming lower and smaller, and the space between the inner edge of the reef and the beach proportionately broader. A section of the reef and island in this state, after a subsidence of several hundred feet, is given by the dotted lines. Coral islets are supposed to have been formed on the reef, and a ship is anchored in the lagoon channel. This channel will be more or less deep, according to the rate of subsidence, to the amount of sediment accumulated in it, and to the growth of the delicately branched corals which can live there. The section in this state resembles in every respect one drawn through an encircled island. In fact, it is a real section, on the scale of 0.517 of an inch to a mile, through Bola Bola in the Pacific. We can now at once see why encircling barrier reefs stand so far from the shores which they front. We can also perceive that a line drawn perpendicularly down from the outer edge of the new reef to the foundation of solid rock beneath the old fringing reef will exceed by as many feet as there have been feet of subsidence that small limit of depth at which the effective corals can live. The little architects having built up their great wall-like mass as the hole sank down upon a basis formed of other corals and their consolidated fragments. Thus the difficulty on this head which appeared so great disappears. If, instead of an island, we had taken the shore of a continent fringed with reefs and had imagined it to have subsided a great straight barrier like that of Australia or New Caledonia separated from the land by a wide and deep channel would evidently have been the result. Let us take our new encircling barrier reef, of which the section is now represented by unbroken lines and which, as I have said, is a real section through Bola Bola and let it go on subsiding. As the barrier reef slowly sinks down the corals will go on vigorously growing upwards but as the island sinks the water will gain inch by inch on the shore. The separate mountains first forming separate islands within one great reef and finally the last and highest pinnacle disappearing. The instant this takes place a perfect atoll is formed. As I have said remove the high land from within an encircling barrier reef and an atoll is left and the land has been removed. We can now perceive how it comes that atolls having sprung from encircling barrier reefs resemble them in general size, form, in the manner in which they are grouped together and in their arrangement in singular double lines for they may be called rude outlined charts of the sunken islands over which they stand. We can further see how it arises that the atolls in the Pacific and Indian oceans extend in lines parallel to the generally prevailing strike of the high islands and the great coastlines of those oceans. I venture therefore to affirm that on the theory of the upward growth of the corals during the sinking of the land all the leading features in those wonderful structures, the lagoon islands or atolls, which have so long excited the attention of voyagers as well as in the no less wonderful barrier reefs, whether encircling small islands or stretching for hundreds of miles along the shores of a continent are simply explained. Footnote 13. It has been highly satisfactory to me to find the following passage in a pamphlet by Mr. Kutoy, one of the naturalists in the great Antarctic expedition of the United States. Quote, having personally examined a large number of coral islands and resided eight months among the volcanic class having shore and partially encircling reefs, I may be permitted to state that my own observations have impressed a conviction of the correctness of the theory of Mr. Darwin. Unquote. The naturalists however of this expedition differ with me on some points respecting coral formations. It may be asked whether I can offer any direct evidence of the subsidence of barrier reefs or atolls, but it must be borne in mind how difficult it must ever be to detect a movement, the tendency of which is to hide underwater the part affected. Nevertheless, at Keeling Atoll I observed on all sides of the lagoon old coconut trees undermined and falling, and in one place the foundation posts of a shed, which the inhabitants asserted had stood seven years before just above high watermark, but now was daily washed by every tide. On Inquiry I found the three earthquakes, one of them severe, had been felt here during the last ten years. At Vanikoro the lagoon channel is remarkably deep, scarcely any alluvial soil has accumulated at the foot of the lofty included mountains, and remarkably few islets have been formed by the heaping of fragments and sand on the wall-like barrier reef. These facts, and some analogous ones, led me to believe that this island must lately have subsided and the reef grown upwards. Here again earthquakes are frequent and very severe. In the society archipelago, on the other hand, where the lagoon channels are almost choked up, where much low alluvial land has accumulated, and where in some cases long islets have been formed on the barrier reefs, facts all showing that the islands have not very lately subsided, only feeble shocks are most rarely felt. In these coral formations, where the land and water seem struggling for mastery, it must be ever difficult to decide between the effects of a change in the set of the tides and of a slight subsidence, that many of these reefs and atolls are subject to changes of some kind as certain. On some atolls the islets appear to have increased greatly within a late period, on others they have been partially or wholly washed away. The inhabitants of parts of the Maldiva archipelago know the date of the first formation of some islets. In other parts the corals are now flourishing on waterwashed reefs, where holes made for graves attest the former existence of inhabited land. It is difficult to believe in frequent changes in the tidal currents of an open ocean, whereas we have in the earthquakes recorded by the natives on some atolls, and in the great fissures observed on other atolls, plain evidence of changes and disturbances in progress in the subterranean regions. It is evident on our theory that coasts merely fringed by reefs cannot have subsided to any perceptible amount, and therefore they must, since the growth of their corals, either have remained stationary or have been upheaved. Now it is remarkable how generally it can be shown by the presence of uprising organic remains that the fringed islands have been elevated, and so far this is indirect evidence in favor of our theory. I was particularly struck with this fact when I found, to my surprise, that the descriptions given by Mr. Quoy and Geymard were applicable not to reefs in general as implied by them, but only to those of the fringing class. My surprise however ceased when I afterwards found that by a strange chance all the several islands visited by these eminent naturalists could be shown by their own statements to have been elevated within a recent geological era. Not only the grand features in the structure of various reefs in atolls, and to their likeness to each other in form, size, and other characters, are explained on the theory of subsidence, which theory we are independently forced to admit in the very areas in question, from the necessity of finding bases for the corals within the requisite depth, but many details in structure and exceptional cases can thus also be simply explained. I will give only a few instances. In barrier reefs it has long been remarked with surprise that the passages through the reef exactly face valleys in the included land, even in cases where the reef is separated from the land by a lagoon channel so wide and so much deeper than the actual passage itself that seems hardly possible that the very small quantity of water or sediment brought down could injure the corals on the reef. Now every reef of the fringing class is breached by a narrow gateway in front of the smallest rivulet, even if dry during the greater part of the year for the mud, sand, or gravel occasionally washed down kills the corals on which it is deposited. Consequently, when an island thus fringed subsides, though most of the narrow gateways will probably become closed by the outward and upward growth of the corals, yet any that are not closed, and some must always be kept open by the sediment and impure water flowing out of the lagoon channel, will still continue to front exactly the upper parts of those valleys at the mouths of which the original basal fringing reef was breached. We can easily see how an island fronted only on one side or on one side with one end or both ends encircled by barrier reefs might after long continued subsidence be converted either into a single wall life reef or into an atoll with a great straight spur projecting from it, or into two or three atolls tied together by straight reefs, all of which exceptional cases actually occur. As the reef-building corals require food, are preyed upon by other animals, are killed by sediment, cannot adhere to a loose bottom, and may be easily carried down to a depth whence they cannot spring up again, we need feel no surprise that the reefs both of atolls and barriers becoming in parts imperfect. The great barrier of New Caledonia is thus imperfect and broken in many parts, hence after long subsidence this great reef would not produce one great atoll 400 miles in length, but a chain or archipelago of atolls, a very nearly the same dimension with those in the Maldiva archipelago. Moreover, in an atoll once breached on opposite sides from the likelihood of the oceanic and tidal currents passing straight through the breaches, it is extremely improbable that the corals, especially during continued subsidence, would ever be able again to unite the rim. If they did not, as the hull sank downwards, one atoll would be divided into two or more. In the Maldiva archipelago there are distinct atolls so related to each other in position, and separated by channels either unfathomable or very deep, the channel between Ross and Ari atolls is 150 fathoms, and that between the North and South Nillindu atolls is 200 fathoms in depth. That it is impossible to look at a map of them without believing that they were once more intimately related. And in this same archipelago, Malos Madu atoll is divided by a bifurcating channel from 100 to 132 fathoms in depth, in such a manner that it is scarcely possible to say whether it ought strictly to be called three separate atolls or one great atoll not yet finally divided. I will not enter on many more details, but I must remark that the curious structure of the northern Maldiva atolls receives, taking into consideration the free entrance of the sea through their broken margins, a simple explanation in the upward and outward growth of the corals, originally based both on small detached reefs in their lagoons, such as occurring common atolls, and on broken portions of the linear marginal reef, such as bounds every atoll of the ordinary form. I cannot refrain from once again remarking on the singularity of these complex structures. A great sandy and generally concave disc rises abruptly from the unfathomable ocean, with its central expanse studded and its edge symmetrically bordered with oval basins of coral rock just lipping the surface of the sea, sometimes clothed with vegetation and each containing a lake of clear water. One more point in detail. As in the two neighboring archipelagos, corals flourish in one and not in the other, and as so many conditions before enumerated must affect their existence, it would be an inexplicable fact if, during the changes to which earth, air, and water are subjected, the reef-building corals were to keep alive for perpetuity on any one spot or area. And as by our theory the areas including atolls and barrier reefs are subsiding, we ought occasionally to find reefs, both dead and submerged. In all reefs, owing to the sediment being washed out of the lagoon channel to leeward, that side is least favorable to the long continued vigorous growth of the corals. Hence, dead portions of reef not unfrequently occur on the leeward side, and these, though still retaining their proper wall-like form, are now in several instances sunk several fathoms beneath the surface. The Chagos group appears from some cause, possibly from the subsidence having been too rapid, at present to be much less favorably circumstance for the growth of reefs than formerly. One atoll has a portion of its marginal reef, nine miles in length, dead and submerged. The second has only a few quite small living points which rise to the surface. A third and fourth are entirely dead and submerged. A fifth is a mere wreck with its structure almost obliterated. It is remarkable that in all these cases the dead reefs and portions of reef lie at nearly the same depth, namely from six to eight fathoms beneath the surface as if they had been carried down by one uniform movement. One of these half-drowned atolls, so-called by Captain Moresby to whom I am indebted for much invaluable information, is a vast size, namely 90 nautical miles across in one direction and 70 miles in another line, and is in many respects eminently curious. As by our theory it follows that new atolls will generally be formed in each new area of subsidence, two way the objections might have been raised, namely that atolls must be increasing indefinitely in number, and secondly that in old areas of subsidence each separate atoll must be increasing indefinitely in thickness if proofs of their occasional destruction could not have been reduced. Thus have we traced the history of these great rings of coral rock from their first origin through their normal changes and through the occasional accidents of their existence to their death and final obliteration. In my volume on coral formations I have published a map in which I have colored all the atolls dark blue, the barrier reefs pale blue, and the fringing reefs red. These latter reefs have been formed whilst the land has been stationary or, as appears from the frequent presence of upraised organic remains whilst it has been slowly rising. Atolls and barrier reefs on the other hand have grown up during the directly opposite movement of subsidence, which movement must have been very gradual and in the case of atolls so vast an amount as to have buried every mountain summit over wide ocean spaces. Now in this map we see that the reefs tinted pale and dark blue which have been produced by the same order of movement as a general rule manifestly stand near each other. Again we see that the areas with the two blue tints are of wide extent and that they lie separate from extensive lines of coast-colored red, both of which circumstances might naturally have been inferred on the theory of the nature of the reefs having been governed by the nature of the earth's movement. It deserves notice that in more than one instance where single red and blue circles approach near each other I can show that there have been oscillations of level. For in such cases the red or fringe circles consist of atolls originally by our theory formed during subsidence but subsequently upheaved and on the other hand some of the pale blue or encircled islands are composed of coral rock which must have been uplifted to its present height before that subsidence took place during which the existing barrier reefs grew upwards. Authors have noticed with surprise that although atolls are the commonest coral structures throughout some enormous oceanic tracks they are entirely absent in other seas as in the West Indies. We can now at once perceive the cause for where there has not been subsidence atolls cannot have been formed and in the case of the West Indies and parts of the East Indies these tracks are known to have been rising within the recent period. The larger areas colored red and blue are all elongated and between the two colors there is a degree of rude alternation as if the rising of one had balanced the sinking of the other. Taking into consideration the proofs of recent elevation both on the fringed coasts and on some others for instance in South America where there are no reefs we are led to conclude that the great continents are for the most part rising areas and from the nature of the coral reefs that the central parts of the great oceans are sinking areas. The East Indian archipelago the most broken land in the world is in most parts an area of elevation but surrounded and penetrated probably in more lines than one by narrow areas of subsidence. I have marked with Vermillion spots all the many known active volcanoes within the limits of this same map. Their entire absence from every one of the great subsiding areas colored either pale or dark blue is most striking and not less so is the coincidence of the chief volcanic chains with the parts colored red which we are led to conclude have either long remain stationary or more generally have been recently upraised. Although a few of the Vermillion spots occur within no great distance of single circles tinted blue yet not one single active volcano is situated within several hundred miles of an archipelago or even small group of atolls. It is therefore a striking fact that in the friendly archipelago which consists of a group of atolls up heaved and since partially worn down two volcanoes and perhaps more are historically known to have been in action. On the other hand although most of the islands in the Pacific which are encircled by barrier reefs are a volcanic origin often with the remnants of craters still distinguishable not one of them is known to have ever been in eruption. Hence in these cases it would appear that volcanoes burst forth into action and become extinguished on the same spots accordingly as elevatory or subsiding movements prevail there. Numberless facts could be adduced to prove that upraised organic remains are common wherever there are active volcanoes but until it could be shown that in areas of subsidence volcanoes were either absent or inactive the inference however probable in itself that their distribution depended on the rising or falling of the earth's surface would have been hazardous. But now I think we may freely admit this important deduction. Taking a final view of the map and bearing in mind the statements made with respect to the upraised organic remains we must feel astonished at the vastness of the areas which have suffered changes in level either downwards or upwards within a period not geologically remote. It would appear also that the elevatory and subsiding movements follow nearly the same laws. Throughout the spaces interspersed with atolls where not a single peak of highland has been left above the level of the sea the sinking must have been immense in amount. The sinking moreover whether continuous or recurrent with intervals sufficiently long for the corals again to bring up their living edifices to the surface must necessarily have been extremely slow. This conclusion is probably the most important one which can be deduced from the study of coral formations and it is one which it is difficult to imagine how otherwise could ever have been arrived at. Nor can I quite pass over the probability of the former existence of large archipelagos of lofty islands where now only rings of coral rocks garsely break the open expanse of the sea throwing sunlight on the distribution of the inhabitants of the other high islands now left standing so immensely remote from each other in the midst of the great oceans. The reef constructing corals have indeed reared and preserved wonderful memorials of the subterranean oscillations of level. We see in each barrier reef a proof that the land has there subsided and in each atoll a monument over an island now lost. We may thus, like unto a geologist who had lived his ten thousand years and kept a record of the passing changes, gain some insight into the great system by which the surface of this globe has been broken up and land and water interchanged. chapter 21 part one of the voyage of the beagle this is a LibriVox recording all LibriVox recordings are in the public domain for more information or to volunteer please visit LibriVox.org recording by Zachary Brewstergeis the voyage of the beagle by Charles Darwin chapter 21 part one Moratius to England moratius beautiful appearance of great critteriform ring of mountains hindus santa Helena history of the changes in the vegetation cause of the extinction of land shells ascension variation in the imported rats volcanic bombs beds of infesoria baia brazil splendor of tropical scenery pernambuco singular reef slavery return to england retrospect on our voyage April 29th in the morning we passed round the northern end of moratius or the isle of france from this point of view the aspect of the island equaled the expectations raised by the many well-known descriptions of its beautiful scenery the sloping plain of the pample mus interspersed with houses and colored by the large fields of sugarcane of a bright green composed the foreground the brilliancy of the green was the more remarkable because it is a color which generally is conspicuous only from a very short distance towards the center of the island groups of wooded mountains rose out of this highly cultivated plain their summits as so commonly happens with ancient volcanic rocks being jagged into the sharpest points masses of white clouds were collected around these pinnacles as if for the sake of pleasing the stranger's eye the whole island with its sloping border and central mountains was adorned with an air of perfect elegance the scenery if i may use such an expression appeared to the site harmonious i spent the greater part of the next day in walking about the town and visiting different people the town is of considerable size and is said to contain 20 000 inhabitants the streets are very clean and regular although the island has been so many years under the english government the general character of the place is quite french englishmen speak to their servants in french and the shops are all french indeed i should think that calais or bouillon was much more anglified there is a very pretty little theater in which operas are excellently performed we were also surprised at seeing large bookseller shops with well-stored shelves music and reading bespeak our approach to the old world of civilization for in truth both australia and america are new worlds the various races of men walking in the streets afford the most interesting spectacle in port louis convicts from india are banished here for life at present there are about 800 and they are employed in various public works before seeing these people i had no idea that the inhabitants of india were such noble looking figures their skin is extremely dark and many of the older men had large moustaches and beards of a snow white color this together with the fire of their expression gave them quite an imposing aspect the greater number had been banished for murder and the worst crimes others for causes which can scarcely be considered as moral faults such as for not obeying from superstitious motives the english laws these men are generally quiet and well conducted from their outward conduct their cleanliness and faithful observance of their strange religious rights it was impossible to look at them with the same eyes as on our wretched convicts in new south wales may first sunday i took a quiet walk along the sea coast to the north of the town the plane in this part is quite uncultivated it consists of a field of black lava smoothed over with coarse grass and bushes the latter being chiefly mimosas the scenery may be described as intermediate in character between that of the galapagos and of tahiti but this will convey a definite idea to very few persons it is a very pleasant country but it has not the charms of tahiti or the grandeur of brazil the next day i ascended lapus a mountain so called from a thumb-like projection which rises close behind the town to a height of 2600 feet the center of the island consists of a great platform surrounded by old broken basaltic mountains with their strada dripping seawards the central platform formed of comparatively recent streams of lava is of an oval shape 13 geographical miles across in the line of its shorter axis the exterior bounding mountains come into that class of structures called craters of elevation which are supposed to have been formed not like ordinary craters but by a great and sudden upheaval there appears to me to be insuperable objections to this view on the other hand i can hardly believe in this and in some other cases that these marginal crateriform mountains are merely the basal remnants of immense volcanoes of which the summits either have been blown off or swallowed up in subterranean abysses from our elevated position we enjoyed an excellent view over the island the country on this side appears pretty well cultivated being divided into fields and studded with farmhouses i was however assured that of the whole land not more than half is yet in a productive state if such be the case considering the present large export of sugar this island at some future period when thickly peopled will be of great value since england has taken possession of it a period of only 25 years the export of sugar is said to have increased 75 fold one great cause of its prosperity is the excellent state of the roads in the neighboring isle of bourbon which remains under the french government the roads are still in the same miserable state as they were here only a few years ago although the french residents must have largely profited by the increased prosperity of their island yet the english government is far from popular third in the evening captain loyde the surveyor general so well known from his examination of the isthmus of panama invited mr. stokes and myself to his country house which is situated on the edge of wilheim plains at about six miles from the port we stayed at this delightful place two days standing nearly 800 feet above the sea the air was cool and fresh and on every side there were delightful walks close by a grand ravine has been warned to a depth of about 500 feet through the slightly inclined streams of lava which have flowed from the central platform fifth captain loyde took us to the rivier noire which is several miles to the southward that i might examine some rocks of elevated coral we pass through pleasant gardens and fine fields of sugarcane growing amidst huge blocks of lava the roads were bordered by hedges of mimosa and near many of the houses there were avenues of the mango some of the views where the peaked hills and the cultivated farms were seen together were exceedingly picturesque and we were constantly tempted to exclaim how pleasant it would be to pass one's life in such quiet abodes captain loyde possessed an elephant and he sent it halfway with us that we might enjoy a ride in true indian fashion the circumstance which surprised me most was its quite noiseless step this elephant is the only one at present on the island but it is said others will be sent for may ninth we sailed from port louis and calling it the cape of good hope on the eighth of july we arrived off senta helena this island the forbidding aspect of which has been so often described rises abruptly like a huge black castle from the ocean near the town as if to complete nature's defense small forts and guns fill up every gap in the rugged rocks the town runs up a flat and narrow valley the houses look respectable and are interspersed with a very few green trees when approaching the anchorage there was one striking view an irregular castle perched on the summit of a lofty hill and surrounded by a few scattered fir trees boldly projected against the sky the next day i obtained lodgings within a stone's throw of napoleon's tomb footnote one after the volumes of eloquence which have poured forth on the subject it is dangerous even to mention the tomb a modern traveler in twelve lines burdens the poor little island with the following titles it is a grave tomb pyramid cemetery sepulcher catacomb sarcophagus minaret and mausoleum end of footnote one it was a capital central situation whence i could make excursions in every direction during the four days i stayed here i wandered over the island from morning to night and examined its geological history my lodgings were situated at a height of about two thousand feet here the weather was cold and boisterous with constant showers of rain and every now and then the whole scene was availed in thick clouds near the coast the rough lava is quite bare in the central and higher parts feldspathic rocks by their decomposition have produced a clay soil which were not covered by vegetation is stained in broad bands of many bright colors at this season the land moistened by constant showers produces a singularly bright green pasture which lower and lower down gradually fades away and at last disappears in latitude sixteen degrees and at the trifling elevation of fifteen hundred feet it is surprising to behold a vegetation possessing a character decidedly british the hills are crowned with the regular plantations of scotch furs and the sloping banks are thickly scattered over with thickets of gorse covered with its bright yellow flowers weeping willows are common on the banks of the rivulets and the hedges are made of the blackberry producing its well-known fruit when we consider that the number of plants now found on the island is seven hundred forty six and that out of these fifty two alone are indigenous species the rest having been imported and most of them from england we see the reason of the british character of the vegetation many of these english plants appear to flourish better than in their native country some also from the opposite quarter of australia succeed remarkably well the many imported species must have destroyed some of the native kinds and it is only on the highest and steepest ridges that the indigenous flora is now predominant the english or rather welsh character of the scenery is kept up by the numerous cottages and small white houses some buried at the bottom of the deepest valleys and others mounted on the crests of the lofty hills some of the views are striking for instance that from nearser w doveton's house where the bold peak called lot is seen over a dark wood of furs the hole being backed by the red water-worn mountains of the southern coast on viewing the island from an eminence the first circumstance which strikes one is the number of the roads and forts the labor bestowed on the public works if one forgets its character as a prison seems out of all proportion to its extent or value there is so little level or useful land that it seems surprising how so many people about five thousand can subsist here the lower orders or the emancipated slaves are i believe extremely poor they complain of the want of work from the reduction in the number of public servants owing to the island having been given up by the east indian company and the consequent emigration of many of the richer people the poverty probably will increase the chief food of the working class is rice with a little salt meat as neither of these articles are the products of the island but must be purchased with money the low wages tell heavily on the poor people now that the people are blessed with freedom a right which i believe they value fully it seems probable that their numbers will quickly increase if so what is to become of the little state of santa elena my guide was an elderly man who had been a goat herd when a boy and knew every step amongst the rocks he was of a race many times crossed and although with the dusty skin he had not the disagreeable expression of a mulatto he was a very civil quiet old man and such appears the character of the greater number of the lower classes it was strange to my ears to hear such a man nearly white and respectively dressed talking with indifference of the times when he was a slave with my companion who carried our dinners and a horn of water which is quite necessary as all the water in the lower valleys is saline i every day took long walks beneath the upper and central green circle the wild valleys are quite desolate and untenanted here to the geologist there were scenes of high interest showing successive changes and complicated disturbances according to my views santa elena has existed as an island from a very remote epoch some obscure proofs however of the elevation of the land are still extant i believe that the central and highest peaks form parts of the rim of a great crater the southern half of which has been entirely removed by the waves of the sea there is moreover an external wall of black basaltic rocks like the coast mountains of moratius which are older than the central volcanic streams on the higher parts of the island considerable numbers of a shell long thought to be a marine species occur embedded in the soil it proved to be a cocklegana or land shell of a very peculiar form footnote two it deserves notice that all the many specimens of this shell found by me in one spot differ as a marked variety from another set of specimens procured from a different spot and a footnote two it proved to be a cocklegana or land shell of a very peculiar form with it i found six other kinds and at another spot an eighth species it is remarkable that none of them are now found living their extinction has probably been caused by the entire destruction of the woods and the consequent loss of food and shelter which occurred during the early part of the last century the history of the changes which the elevated planes of longwood and deadwood have undergone as given in general beatson's account of the island is extremely curious both planes it is said in former times were covered with wood and were therefore called the great wood so late as the year seventeen sixteen there were many trees but in seventeen twenty four the old trees had mostly fallen and his goats and hogs had been suffered to range about all the young trees had been killed it appears also from the official records that the trees were unexpectedly some years afterwards succeeded by a wire grass which spread over the whole surface footnote three beatson's santa helena introductory chapter page four end of footnote three general beatson adds that now this plane is covered with fine sward and has become the finest piece of pasture on the island the extent of surface probably covered by wood at a former period is estimated at no less than two thousand acres at the present day scarcely a single tree can be found there it is also said that in seventeen oh nine there were quantities of dead trees in sandy bay this place is now so utterly desert that nothing but so well attested an account could have made me believe that they could ever have grown there the fact that the goats and hogs destroyed all the young trees as they sprang up and that in the course of time the old ones which were saved from their attacks perished from age seems clearly made out goats were introduced in the year fifteen oh two eighty six years afterwards in the time of cavendish it is known that they were exceedingly numerous more than a century afterwards in seventeen thirty one when the evil was complete and irretrievable an order was issued that all stray animals should be destroyed it is very interesting thus to find that the arrival of animals at santa helena in fifteen oh one did not change the whole aspect of the island until a period of two hundred and twenty years had elapsed for the goats were introduced in fifteen oh two and in seventeen twenty four it is said the old trees had mostly fallen there can be little doubt that this great change in the vegetation affected not only the land shells causing eight species to become extinct but likewise a multitude of insects santa helena situated so remote from any continent in the midst of a great ocean and possessing a unique flora excites our curiosity the eight land shells though now extinct and one living succion a are peculiar species found nowhere else mr. cumming however informs me that in english helix is common here its eggs no doubt having been imported in some of the many introduced plants mr. cumming collected on the coast sixteen species of seashells of which seven as far as he knows are confined to this island birds and insects footnote four among these few insects i was surprised to find a small aphodius novum species and an aura sites both extremely numerous under dung when the island was discovered it certainly possessed no quadruped accepting perhaps a mouse it becomes therefore a difficult point to ascertain whether these stercovorus insects have since been imported by accident or if aborigines on what food they formerly subsisted on the banks of the platea where from the vast number of claddle and horses these fine planes of turf are richly maneuvered it is vain to seek the many kinds of dung feeding beetles which occur so abundantly in europe i observed only an aura sites the insects of this genus in europe generally feed on decayed vegetable matter and two species of finace common in such situations on the opposite side of the cordiera in kylo another species of finace is exceedingly abundant and it buries the dung of the cattle in large earthen balls beneath the ground there is reason to believe that the genus finace before the introduction of cattle acted as scavengers to man in europe beetles which find support in the matter which has already contributed toward the life of other and larger animals are so numerous that there must be considerably more than 100 different species considering this and observing what a quantity of food of this kind is lost on the plains of la platea i imagined i saw an instance where man had disturbed that chain by which so many animals are linked together in their native country in van demon's land however i found four species of onthopagus two of aphodias and one of a third genus very abundantly under the dung of cows yet these latter animals had been then introduced only 33 years previous to that time the kangaroo and some other small animals were the only quadrupeds and their dung is of a very different quality from that of their successors introduced by man in england the greater number of stirvacorus beetles are confined in their appetites that is they do not depend indifferently on any quadruped for the means of subsistence the change therefore in habits which must have taken place in van demon's land is highly remarkable i am indebted to the reverend fw hope who i hope will permit me to call him my master in entomology for giving me the names of the forgoing insects and a footnote birds and insects as might have been expected are very few in number indeed i believe all the birds have been introduced within late years partridges and pheasants are tolerably abundant the island is much too english not to be subject to strict game laws i was told of a more unjust sacrifice to such ordinances than ever i heard of even in england the poor people formally used to burn a plant which grows on the coast rocks and export the soda from its ashes but a peremptory order came out prohibiting this practice and giving as a reason that the partridges would have nowhere to build in my walks i passed more than once over the grassy plain bounded by deep valleys on which longwood stands viewed from a short distance it appears like a respectable gentleman's country seat in front there are a few cultivated fields and beyond them the smooth hill of colored rocks called the flagstaff and the rugged square black mass of the barn on the whole the view was rather bleak and uninteresting the only inconvenience i suffered during my walks was from the impetuous winds one day i noticed a curious circumstance standing on the edge of a plane terminated by a great cliff of about a thousand feet in depth i saw at the distance of a few yards right to windward some turn struggling against a very strong breeze whilst where i stood the air was quite calm approaching close to the brink where the current seemed to be deflected upwards from the face of the cliff i stretched out my arm and immediately felt the full force of the wind an invisible barrier two yards in width separated perfectly calm air from a strong blast i so much enjoyed my rambles among the rocks and mountains of santa helena that i felt almost sorry on the morning of the 14th to descend to the town before noon i was on board and the beagle made sail on the 19th of july we reached ascension those who have beheld a volcanic island situated under an arid climate will at once be able to picture to themselves the appearance of ascension they will imagine smooth conical hills of a bright red color with their summits generally truncated rising separately out of a level service of black rugged lava a principal mound in the center of the island seems the father of the lesser cones it is called green hill its name being taken from the faintest hinge of that color which at this time of year is barely perceptible from the anchorage to complete the desolate scene the black rocks on the coast are lashed by a wild and turbulent sea the settlement is near the beach it consists of several houses and barracks placed irregularly but well built of white freestone the only inhabitants are marines and some negroes liberated from slave ships who are paid and viddled by government there is not a private person on the island many of the marines appeared well contented with their situation they think it better to serve their one and twenty years on shore let it be what it may then in a ship in this choice if i were a marine i should most heartily agree the next morning i ascended green hill two thousand eight hundred forty feet high and then swalked across the island to the windward point a good cart road leads from the coast settlement to the houses gardens and fields placed near the summit of the central mountain on the roadside there are milestones and likewise cisterns where each thirsty passerby can drink some good water similar care is displayed in each part of the establishment and especially in the management of the springs so that a single drop of water may not be lost indeed the whole island may be compared to a huge ship kept in first rate order i could not help when admiring the active industry which had created such effects out of such means at the same time regretting that it had been wasted on so poor and trifling an end monsieur le son has remarked with justice that the english nation would have thought of making the island of ascension a productive spot any other people would have held it as a mere fortress in the ocean near this coast nothing grows further inland an occasional green castor oil plant and a few grasshoppers true friends of the desert may be met with some grass is scattered over the surface of the central elevated region and the whole much resembles the worst parts of the welsh mountains but scanty as the pasture appears about 600 sheep many goats a few cows and horses all thrive well on it of native animals land crabs and rats swarm in numbers whether the rat is really indigenous may well be doubted there are two varieties as described by mr waterhouse one is of a black color with fine glossy fur and lives on the grassy summit the other is brown colored and less glossy with longer hairs and lives near the settlement on the coast both these varieties are one third smaller than the common black rat m ratus and they differ from it both in the color and character of their fur but in no other essential respect i can hardly doubt that these rats like the common mouse which is also run wild have been imported and as at the galapagos have varied from the effect of the new conditions to which they have been exposed hence the variety on the summit of the island differs from that on the coast of native birds there are none but the guinea fowl imported from the cape divert islands is abundant and the common fowl has likewise run wild some cats which were originally turned out to destroy the rats and mice have increased so as to become a great plague the island is entirely without trees in which and in every other respect it is very far inferior to santa helena one of my excursions took me towards the southwest extremity of the island the day was clear and hot and i saw the island not smiling with beauty but staring with naked hideousness the lava streams are covered with hummocks and are rugged to a degree which geologically speaking is not of easy explanation the intervening spaces are concealed with layers of pumice ashes and volcanic tough whilst passing this end of the island at sea i could not imagine what the white patches were with which the whole plane was modeled i now found that they were seafowl sleeping in such full confidence that even in midday a man could walk up and seize hold of them these birds were the only living creatures i saw during the whole day on the beach a great surf although the breeze was light came tumbling over the broken lava rocks the geology of this island is in many respects interesting in several places i noticed volcanic bombs that is masses of lava which have been shot through the air whilst fluid and have consequently assumed a spherical or pear shape not only their external form but in several cases their internal structure shows in a very curious manner that they have revolved in their aerial course the internal structure of one of these bombs when broken is represented very accurately in the woodcut the central part is coarsely cellular the cells decreasing inside towards the exterior where there is a shell-like case about the third of an inch in thickness of compact stone which again is overlaid by the outside crust of finely cellular lava i think there can be little doubt first that the external crust cooled rapidly in the state in which we now see it secondly that the still fluid lava within was packed by the centrifugal force generated by the revolving of the bomb against the external cooled crust and so produced the solid shell of stone and lastly that the centrifugal force by relieving the pressure in the more central parts of the bomb allowed the heated vapors to expand their cells thus forming the core cellular mass of the center a hill formed of the older series of volcanic rocks and which has been incorrectly considered as the crater of a volcano is remarkable from its broad slightly hollowed and circular summit having been filled up with many successive layers of ashes and fine scoriae these saucer-shaped layers crop out on the margin forming perfect rings of many different colors giving to the summit a most fantastic appearance one of these rings is white and broad and resembles a course round which horses have been exercise hence the hill has been called the devil's writing school i brought away specimens of one of the tophatious layers of a pinkish color and it is a most extraordinary fact that professor erinberg footnote five monats der könig academy du vis du berlin vom april 1845 and a footnote i brought away specimens of one of the tophatious layers of a pinkish color and it is a most extraordinary fact that professor erinberg finds it almost wholly composed of matter which has been organized he detects in it some salacious shielded fresh water in fissoria and no less than 25 different kinds of the salacious tissue of plants chiefly of grasses from the absence of all carbonaceous matter professor erinberg believes that these organic bodies have passed through the volcanic fire and have been erupted in the state in which we now see them the appearance of the layers induced me to believe that they had been deposited under water though from the extreme dryness of the climate i was forced to imagine that torrents of rain had probably fallen during some great eruption and that thus a temporary lake had been formed into which the ashes fell but it may now be suspected that the lake was not a temporary one anyhow we may feel sure that at some former epoch the climate and productions of ascension were very different from what they now are where on the face of the earth can we find a spot on which close investigation will not discover signs of that endless cycle of change to which this earth has been is and will be subjected end of chapter 21 part one recording by zachary bruster geist greenbelt mariland june 2007 chapter 21 part two of the voyage of the beagle this is a libra vox recording all libra vox recordings are in the public domain for more information or to volunteer please visit libra vox dot org recording by zachary bruster geist the voyage of the beagle by charles darwin chapter 21 part two moratius to england on leaving ascension we sailed for baia on the coast of brazil in order to complete the chronometrical measurement of the world we arrived there on august 1st and stayed four days during which i took several long walks i was glad to find my enjoyment in tropical scenery had not decreased from the want of novelty even in the slightest degree the elements of the scenery are so simple that they are worth mentioning as a proof on what trifling circumstances exquisite natural beauty depends the country may be described as a level plane of about 300 feet in elevation which in all parts has been worn into flat bottomed valleys this structure is remarkable in a granitic land but is nearly universal in all those softer formations of which planes are usually composed the whole surface is covered by various kinds of stately trees interspersed with patches of cultivated ground out of which houses convents and chapels arise it must be remembered that within the tropics the wild luxuriance of nature is not lost even in the vicinity of large cities for the natural vegetation of the hedges and hillsides overpowers in picturesque effect the artificial labor of man hence there are only a few spots where the bright red soil affords a strong contrast with the universal clothing of green from the edges of the plane there are distant views either of the ocean or of the great bay with its low wooded shores and on which numerous boats and canoes show their white sails accepting from these points the scene is extremely limited following the level pathways on each hand only glimpses into the wooded valleys below can be obtained the houses I may add and especially the sacred edifices are built in a peculiar and rather fantastic style of architecture they are all whitewashed so that when illuminated by the brilliant sun of midday and as seen against the pale blue sky of the horizon they stand out more like shadows than real buildings such are the elements of the scenery but it is a hopeless attempt to paint the general effect learned naturalists describe these scenes of the tropics by naming a multitude of objects and mentioning some characteristic feature of each to a learned traveler this possibility may communicate some definite ideas but who else from seeing a plant in an herbarium can imagine its appearance when growing in its native soil who from seeing choice plants in a hot house can magnify some into the dimensions of forest trees and crowd others into an entangled jungle who when examining the cabinet of the entomologist the gay exotic butterflies and singular cicadas will associate with these lifeless objects the ceaseless harsh music of the latter and the lazy flight of the former the sure accompaniments of the still glowing noonday of the tropics it is when the sun has attained its greatest height that such scenes should be viewed then the dense splendid foliage of the mango hides the ground with its darkest shade whilst the upper branches are rendered from the profusion of light of the most brilliant green in the temperate zones the case is different the vegetation there is not so dark or so rich and hence the rays of the declining sun tinged of a red purple or bright yellow color add most to the beauties of those climbs when quietly walking along the shady pathways and admiring each successive view i wished to find language to express my ideas epithet after epithet was found too weak to convey to those who have not visited the intertropical regions the sensation of delight which the mind experiences i have said that the plants in a hot house fail to communicate a just idea of the vegetation yet i must recur to it the land is one great wild untidy luxuriant hot house made by nature for herself but taken possession of by man who has studded it with gay houses and formal gardens how great would be the desire in every admirer of nature to behold if such were possible the scenery of another planet yet to every person in europe it may be truly said that at the distance of only a few degrees from his native soil the glories of another world are open to him in my last walk i stopped again and again to gaze on these beauties and endeavored to fix in my mind forever an impression which at the time i knew sooner or later must fail the form of the orange tree the coco nut the palm the mango the tree fern the banana will remain clear and separate but the thousand beauties which unite these into one perfect scene must fade away yet they will leave like a tail heard in childhood a picture full of indistinct but most beautiful figures august 6th in the afternoon we stood out to see with the intention of making a direct course to the caped of air islands unfavorable winds however delayed us and on the 12th we ran into Pernambuco a large city on the coast of brazil in latitude eight degrees south we anchored outside the reef but in a short time a pilot came on board and took us into the inner harbor where we lay close to the town Pernambuco is built on some narrow and low sand banks which are separated from each other by shoal channels of salt water the three parts of the town are connected together by two long bridges built on wooden piles the town is in all parts disgusting the streets being narrow ill paved and filthy the houses tall and gloomy the season of heavy rains had hardly come to an end and hence the surrounding country which is scarcely raised above the level of the sea was flooded with water and i failed in all my attempts to take walks the flat swampy land on which Pernambuco stands is surrounded at the distance of a few miles by a semicircle of low hills or rather by the edge of a country elevated perhaps 200 feet above the sea the old city of olinda stands on one extremity of this range one day i took a canoe and proceeded up one of the channels to visit it i found the old town from its situation both sweeter and cleaner than that of Pernambuco i must hear commemorate what happened for the first time during our nearly five years wandering namely having met with a want of politeness i was refused in a sullen manner at two different houses and obtained with difficulty from a third permission to pass through their gardens to an uncultivated hill for the purpose of viewing the country i feel glad that this happened in the land of the brazilians for i bear them no good will a land also of slavery and therefore of moral debasement a spaniard would have felt ashamed at the very thought of refusing such a request or of behaving to a stranger with rudeness the channel by which we went to and returned from olinda was bordered on each side by mangroves which sprang like a miniature forest out of the greasy mudbanks the bright green color of these bushes always reminded me of the rank grass in a churchyard both are nourished by putrid exhalations the one speaks of death past and the other too often of death to come the most curious object which i saw in this neighborhood was the reef that forms the harbor i doubt whether in the whole world any other natural structure has so artificial an appearance footnote six i have described this bar in detail in the london and edinborough philosophical magazine volume 11 1841 page 257 end of footnote it runs for a length of several miles in an absolutely straight line parallel to and not far distance from the shore it varies in width from 30 to 60 yards and its surface is level and smooth it is composed of obscurely stratified hard sandstone at high water the waves break over it at low water its summit is left dry and it might be mistaken for a breakwater erected by cyclopean workmen on this coast the currents of the sea tend to throw up in front of the land long spits and bars of loose sand and on one of these part of the town of pernambuco stands in former times the long spit of this nature seems to have become consolidated by the percolation of calcarius matter and afterwards to have been gradually upheaved the outer and loose parts during this process having been worn away by the action of the sea and the solid nucleus left as we now see it although night and day the waves of the open atlantic turbid with sediment are driven against the steep outside edges of this wall of stone yet the oldest pilots know of no tradition of any change in its appearance this durability is much the most curious fact in its history it is due to a tough layer of few inches thick of calcarius matter wholly formed by the successive growth and death of the small shells of syrpuli together with some few barnacles and nullapore these nullapore which are hard very simply organized sea plants play an analogous and important part in protecting the upper surfaces of coral reefs behind and within the breakers where the true corals during the outward growth of the mass become killed by exposure to the sun and air these insignificant organic beings especially the syrpuli have done good service to the people of pernambuco for without their protective aid the bar of sandstone would inevitably have been long ago worn away and without the bar there would have been no harbor on the 19th of august we finally left the shores of brazil i thank god i shall never again visit a slave country to this day if i hear a distant scream it recalls with painful vividness my feelings when passing a house near pernambuco i heard the most pitiable moans and could not but suspect that some poor slave was being tortured yet knew that i was as powerless as a child even to remonstrate i suspected that these moans were from a tortured slave for i was told that this was the case in another instance near Rio de Janeiro i lived opposite to an old lady who kept screws to crush the fingers of her female slaves i've stayed in a house where a young household mulatto daily and hourly was reviled beaten and persecuted enough to break the spirit of the lowest animal i've seen a little boy six or seven years old struck thrice with a horse whip before i could interfere on his naked head or having handed me a glass of water not quite clean i saw his father tremble at a mere glance from his master's eye these latter cruelties were witnessed by me in a spanish colony in which it has always been said that slaves are better treated than by the portuguese english or other european nations i've seen at Rio de Janeiro a powerful negro afraid to ward off a blow directed as he thought at his face i was present when a kind-hearted man was on the point of separating forever the men women and little children of a large number of families who had long lived together i will not even allude to the many heart-sickening atrocities which i authentically heard of nor would i have mentioned the above revolting details had i not met with several people so blinded by the constitutional gaiety of the negro as to speak of slavery as a tolerable evil such people have generally visited at the houses of the upper classes where the domestic slaves are usually well treated and they have not like myself lived amongst the lower classes such inquirers will ask slaves about their condition they forget that the slave must indeed be dull who does not calculate on the chance of his answer reaching his master's ears it is argued that self-interest will prevent excessive cruelty as if self-interest protected our domestic animals which are far less likely than degraded slaves to stir up the rage of their savage masters it is an argument long since protested against with noble feeling and strikingly exemplified by the ever illustrious humboldt it is often attempted to palliate slavery by comparing the state of slaves with our poorer countrymen if the misery of our poor because not by the laws of nature but by our institutions great as our sin but how this bears on slavery i cannot see as well might the use of the thumbscrewed be defended in one land by showing that men in another land suffered from some dreadful disease those who look tenderly at the slave owner and with a cold heart at the slave never seem to put themselves into the position of the latter what a cheerless prospect with not even a hope of change picture to yourself the chance ever hanging over you of your wife and your little children those objects which nature urges even the slave to call his own being torn from you and sold like beasts to the first bidder and these deeds are done and palliated by men who profess to love their neighbors as themselves who believe in god and pray that his will be done on earth it makes one's blood boil yet heart tremble to think that we englishmen and our american descendants with their boastful cry of liberty have been and are so guilty but it is a consolation to reflect that we at least have made a greater sacrifice than ever made by any nation to expiate our sin on the last day of august we anchored for the second time at porto priah in the cape de verre archipelago thence we proceeded to the azores where we stayed six days on the second of october we made the shore of england and at fulmouth i left the beagle having lived on board the good little vessel nearly five years our voyage having come to an end i will take a short retrospect of the advantages and disadvantages the pains and pleasures of our circumnavigation of the world if a person asked my advice before undertaking a long voyage my answer would depend upon his possessing a decided taste for some branch of knowledge which could by this means be advanced no doubt it is a high satisfaction to behold various countries and the many races of mankind but the pleasures gained at the time do not counterbalance the evils it is necessary to look forward to a harvest however distant that may be when some fruit will be reaped some good affected many of the losses which must be experienced are obvious such as that of the society of every old friend and of the site of those places with which every dearest remembrance is so intimately connected these losses however are at the time partly relieved by the exhaustless delight of anticipating the long wish for day of return if as poets say life is a dream i am sure in a voyage these are the visions which best serve to pass away the long night other losses although not at first felt tell heavily after a period these are the want of room of seclusion of rest the jading feeling of constant hurry the privation of small luxuries the loss of domestic society and even of music and the other pleasures of imagination when such trifles are mentioned it is evident that the real grievances accepting from accidents of a sea life are at an end the short space of 60 years has made an astonishing difference in the facility of distant navigation even in the time of cook a man who left his fireside for such expeditions underwent severe privations a yacht now with every luxury of life can circumnavigate the globe besides the vast improvements in ships and natural resources the whole western shores of america are thrown open and australia has become the capital of a rising content how different are the circumstances to a man shipwrecked at the present day in the pacific to what they were in the time of cook since his voyage a hemisphere has been added to the civilized world if a person suffer much from seasickness let him weigh it heavily in the balance i speak from experience it is no trifling evil cured in a week if on the other hand he take pleasure in naval tactics he will assuredly have full scope for his taste but it must be born in mind how large a proportion of the time during a long voyage is spent on the water as compared with the days in harbour and what are the boasted glories of the illimitable ocean a tedious waste a desert of water as the arabian calls it no doubt there are some delightful scenes a moonlight night with the clear heavens and the dark glittering sea and the white sails filled by the soft air of a gently blowing trade wind a dead calm with the heaving surface polished like a mirror and all still except the occasional flapping of the canvas it is well once to behold a squall with its rising arch and coming fury or the heavy gale of wind and mountainous waves i confess however my imagination had painted something more grand more terrific in the full grown storm it is an incomparably finer spectacle when beheld on shore where the waving trees the wild flight of the birds the dark shadows and bright lights the rushing of the torrents all proclaim the strife of the unloosed elements at sea the albatross and little petrol fly as if the storm were their proper sphere the water rises and sinks as if fulfilling its usual task the ship alone and its inhabitants seen the objects of wrath on a forlorn and weather beaten coast the scene is indeed different but the feelings partake more of horror than of wild delight let us now look at the brighter side of the past time the pleasure derived from beholding the scenery and the general aspect of the various countries we have visited has decidedly been the most constant and highest source of enjoyment it is probable that the picturesque beauty of many parts of europe exceeds anything which we beheld but there is a growing pleasure in comparing the character of the scenery in different countries which to a certain degree is distinct from merely admiring its beauty it depends chiefly on an acquaintance with the individual parts of each view i am strongly induced to believe that as in music the person who understands every note will if he also possesses a proper taste more thoroughly enjoy the whole so he who examines each part of a fine view may also thoroughly comprehend the full and combined effect hence a traveler should be a botanist for an all-views plants form the chief embellishment group masses of naked rock even in the wildest forms and they may for a time afford a sublime spectacle but they will soon grow monotonous paint them with bright and varied colors as in northern chile they will become fantastic clothe them with vegetation they must form a decent if not a beautiful picture when i say that the scenery of parts of europe is probably superior to anything which we beheld i accept as a class by itself that of the intertropical zones the two classes cannot be compared together but i have already often enlarged on the grandeur of those regions as the force of impressions generally depends on preconceived ideas i may add that mine were taken from the vivid descriptions in the personal narrative of humboldt which far exceed and merit anything else which i have read yet with these high wrought ideas my feelings were far from partaking of a tinge of disappointment on my first and final landing on the shores of brazil among the scenes which are deeply impressed on my mind none exceed in sublimity the primeval forests undefaced by the hand of man whether those of brazil were the powers of life are predominant or those of tiara del fuego where death and decay prevail both are temples filled with the varied productions of the god of nature no one can stand in these solitudes unmoved and not feel that there is more in man than the mere breath of his body in calling up images of the past i find that the planes of patagonia frequently cross before my eyes yet these planes are pronounced by all wretched and useless they can be described only by negative characters without habitations without water without trees without mountains they support merely a few dwarf plants why then and the case is not peculiar to myself have these arid wastes taken so firm a hold on my memory why have not the still more level the greener and more fertile pampas which are serviceable to mankind produced an equal impression i can scarcely analyze these feelings but it must be partly owing to the free scope given to the imagination the planes of patagonia are boundless for they are scarcely passable and hence unknown they bear the stamp of having lasted as they are now for ages and there appears no limit to their duration through future time if as the ancient supposed the flat earth was surrounded by an impassable breadth of water or by deserts heated to an intolerable excess who would not look at these last boundaries to man's knowledge with deep but ill-defined sensations lastly of natural scenery the views from lofty mountains though certainly in one sense not beautiful are very memorable when looking down from the highest crest of the cordiera the mind undisturbed by minute details was filled with the stupendous dimensions of the surrounding masses of individual objects perhaps nothing is more certain to create astonishment than the first sight in his native haunt of a barbarian of man in his lowest and most savage state one's mind hurries back over past centuries and then asks could our progenitors have been men like these men whose very signs and expressions are less intelligible to us than those of the domesticated animals men who do not possess the instinct of those animals nor yet appear to boast of human reason or at least of arts consequent on that reason I do not believe it is possible to describe or paint the difference between savage and civilized man it is the difference between a wild and tame animal and part of the interest in beholding a savage is the same which would lead everyone to desire to see the lion in his desert the tiger tearing his prey in the jungle or the rhinoceros wandering over the wild plains of Africa among the other most remarkable spectacles which we have beheld may be ranked the southern cross the cloud of Magellan and the other constellations of the southern hemisphere the water spout the glacier leaning its blue stream of ice overhanging the sea in a bold precipice a lagoon island raised by the reef building corals an active volcano and the overwhelming effects of a violent earthquake these latter phenomena perhaps possess for me a peculiar interest from their intimate connection with the geological structure of the world the earthquake however must be to everyone a most impressive event the earth considered from our earliest childhood as the type of solidity has oscillated like a thin crust beneath our feet and in seeing the labored works of man in a movement overthrown we feel the insignificance of his boasted power it has been said that the love of the chase is an inherent delight in man a relic of an instinctive passion if so i am sure the pleasure of living in the open air with the sky for a roof and the ground for a table is part of the same feeling it is the savage returning to his wild and native habits i always look back to our boat cruises and my land journeys went through unfrequented countries with an extreme delight which no scenes of civilization could have created i do not doubt that every traveler must remember the glowing sense of happiness which he experienced when he first breathed in a foreign climb where the civilized man had seldom or never trod there are several other sources of enjoyment in a long voyage which are of a more reasonable nature the map of the world ceases to be a blank it becomes a picture full of the most varied and animated figures each part assumes its proper dimensions continents are not looked at in the light of islands or islands considered as mere specs which are in truth larger than many kingdoms of europe africa or north and south america are well sounding names and easily pronounced but it is not until having sailed for weeks along small portions of their shores that one is thoroughly convinced what vast spaces on our immense world these names imply from seeing the present state it is impossible not to look forward with high expectations to the future progress of nearly an entire hemisphere the march of improvement consequent on the introduction of christianity throughout the south sea probably stands by itself in the records of history it is the more striking when we remember that only 60 years since cook whose excellent judgment none will dispute could foresee no prospect of a change yet these changes have now been affected by the philanthropic spirit of the british nation in the same quarter of the globe australia is rising or indeed may be said to have risen into a grand center of civilization which at some not very remote period will rule an empress over the southern hemisphere it is impossible for an englishman to behold these distant colonies without a high pride and satisfaction to hoist the british flag seems to draw with it as a certain consequence wealth prosperity and civilization in conclusion it appears to me that nothing can be more improving to a young naturalist than a journey in distant countries it both sharpens and partly allays that wanton craving which as sir j hercial remarks a man experiences although every corporeal sense be fully satisfied the excitement from the novelty of objects and the chance of success stimulate him to increase activity moreover as a number of isolated facts soon become uninteresting the habit of comparison leads to generalization on the other hand as the traveler stays but a short time in each place his descriptions must generally consist of mere sketches instead of detailed observations hence arises as i've found to my cost a constant tendency to fill up the wide gaps of knowledge by inaccurate and superficial hypotheses but i have too deeply enjoyed the voyage not to recommend any naturalist although he must not expect to be so fortunate in his companions as i have been to take all chances and to start on travels by land if possible if otherwise on a long voyage he may feel assured he will meet with no difficulties or dangers accepting in rare cases nearly so bad as he beforehand anticipates in a moral point of view the effect ought to be to teach him good humor patients freedom from selfishness the habit of acting for himself and of making the best of every occurrence in short he ought to partake of the characteristic qualities of most sailors traveling ought also to teach him distrust but at the same time he will discover how many truly kind-hearted people there are with whom he never before had or ever again will have any further communication who yet are ready to offer him the most disinterested assistance end of chapter 21 part 2 recording by Zachary Brewstergeis Greenbelt Maryland June 2007 end of the voyage of the Beagle by Charles Darwin