 This is part of the Montpelier play series. My name's Eric Ample. I am a student UDM in the field match list program, and I'm organizing the play series. Which, this is the seventh event, I believe. So, thank you for, if you've been to the past events, thank you, if you are coming to the, if you're interested in coming to more, there's gonna be one more in this series, and there's a question box in the front for if you want to see something new come up, come up down the pipe. I want to thank our sponsors, The Hunger Mountain Co-op, The Bed & Darius Foundation, and the Vermont Community Foundation. And I just want to introduce our speaker today, who is Sean Beckett, over here, who's gonna talk to you. And then, hopefully, you can come tomorrow, too, for a really great field walk at nine in the morning. Sean is, works at North Branch Hager Center here, and just really excited about rocks. So, hopefully, you can share what I say, what would be okay. Thank you. All right, hello, everybody. It's a pleasure to see you all. Thanks for coming out to talk about rocks all night. So, I have some notes to myself here, which I need to make bigger, hang on, one second. Well, I guess I won't. So, the first note to myself is to tell you where we're meeting tomorrow. So, I don't forget. So, if anyone wants to join us for the field walk tomorrow, we're gonna meet at, the field walk is nine to noon, and it's gonna be starting at Gateway Park. So, if you go down Route 2 past Greenmont Cemetery, just across the street from Greenmont Cemetery, there's kind of like a parking area, that's actually called Gateway Park, right under the interstate. It's like a fishing access. There's lots of place for parking there, so we'll convene there, and we're gonna walk across into Greenmont Cemetery and check out some escarpments at the back of the cemetery. So, we're just meeting at Gateway Park. And then, we're gonna travel to a couple other places around town over the course of the morning. But, if you wanna join us, nine o'clock at Gateway Park is the place. We should encourage carpooling, Paige, yeah. So, if you know anyone else in the room who might be going, see if you can carpool to Gateway Park. We can also carpool. Gateway Park would be a fine place to leave a car, too, if folks wanna carpool from there, across town after that. We'll be staying within the city limits pretty much the whole morning, so. Sound good? Okay. My name's Sean Beckett. I'm the program director here at North Branch Nature Center. I teach in the graduate of the UVM Field Naturalist Program as well. I teach with the Vermont Master Naturals Program. Many of you have done this program, or are in it currently. Raise your hand if that's the case. One, two, three, four. Nice. And I've found that in my explorations as an ecologist, I keep coming back again and again to the fact that rocks are really the most important thing out there. Everything can be explained by the geology, by what's going on underfoot. As a botanist, we can walk into the woods and we can see particular kinds of tree species and expect where they're gonna be growing. And if we see a maple tree, we know there's gonna be probably a yellow birch tree growing nearby. There's certain patterns that we can expect to see as ecologists when we walk around our natural landscape. But there's also incredible connections between our geologic story and our natural landscape, or I should say the botanical world on top of that. And I think in certain places, if you were to tell me, or to tell someone who knew these things, what kind of rock you were standing on? Not only could that person then even imagine what kind of forest was growing on top of it, but could even imagine the sound of the bird songs that were singing on top of that. So when I think of the Moncton Quartzite formation in Burlington, I am listening to the sounds of wood thrushes in my head. And when I think about the Moortown formation, fillite formations in Western Montpelier, I'm thinking about the sounds of hermit thrushes in my head. I'm thinking about the hemlock trees that are growing around. So I just love the geological determinism of it all, how what's underfoot really totally explains what's happening around us. And that doesn't stop with the natural world either. I would argue that our built environment is, can be tied back in many ways to what's happening geologically in an area. And one of the things I wanna introduce tonight, just plant the seed, is that many of the decisions we've made around Montpelier's architecture and what we're building our buildings out of and why and where can be tied, either in large part or small part, to what's going on underground. And I just think that's a really cool idea. And it makes our city unique to place, right? I should also take a moment to acknowledge that we are on Western Abinaki land. And although tonight, I'm introducing this story to us in terms of how geology is connected to our way of life. But this is not news to the Abinaki people who for 12,000 years, geology has been part of their way of life. And this is not a new story to them. This is a 12,000 year old story. And so I'm inviting you to start this story tonight. And we're gonna talk a lot about the, we're gonna go back into the past 500 million years and we're gonna go fast forwarding up to today and looking at how we, some of our buildings are where they are. So this is a beautiful water color by a field naturalist alumni, Claire Dacey is her name. And this is nice and representative of the parts of the earth that we tend to think about are the parts that are in color here. The parts that we can see, the waters, the trees, the roads and buildings and houses, the birds, the sky, right? But those are all layers of our, landscape layer cake, but those layers go underground too into the ground. When we talk about geology, just to get us all on the same page here, we're talking about one of two things. When we talk about geology, we can be talking about the bedrock, right? And bedrock is beneath everywhere on the planet. So whether you're standing here, whether you're in the middle of the ocean, if you go down far enough, you're going to hit bedrock. In many cases, your foot is already on bedrock as soon as you walk out the door. Or if you're up on top of a mountain or on the edge of a ledge, you're touching bedrock. Rock that is connected contiguously all the way through the crust of the earth. In many cases, that bedrock is buried under tens or hundreds of feet of sediment or beneath hundreds of feet of water. But if you go down far enough, you're going to hit bedrock. So when we talk about geology, we could be talking about bedrock. We could also be talking about superficial stuff or glacier junk, I kind of call it. So anything that's not nailed down into the bedrock is susceptible to be moved around by all the dynamic forces in our landscape. So glacier is coming and scouring the landscape. Streams eroding away our mountains, moving silt and clay and cobble and sediment across the land, you know, spitting it out into huge piles here and scouring it away there and leaving sediment of all different sizes from finest flower to boulders as big as houses kind of strewn about our landscape in non-random ways. So geologists really have two things at once to study, the bedrock and then all the superficial stuff on top of it. So when it came to thinking about how we would break down tonight's talk, it made sense to do this in two acts. Act one is going to be about the bedrock and act two is going to be about all the superficial stuff sitting on top of it. So act one, we're going to call the geologic frontier of Vermont because I'm going to argue that Montpelier is the geologic frontier of Vermont. It's a very interesting place geologically and it's very apropos that the seat of state government sits right here. And in a way, Montpelier's bedrock geology is descriptive of the entire story of Vermont's geological history. In act two, we're going to call when the earth is flat and talking about how the glaciers and the ice ages have shaped a lot of our landscape around us. So going into act one here, we have, we're going to break this into basically three scenes. There's three things that I want you to walk away with in our bedrock geology story. And there's going to be three different types of rocks that you're going to hopefully be familiar with and be able to recognize when you see after tonight. And these three different types of rock represents three different scenes in Vermont's bedrock geology story. We have scene one, is the formation of the green mountains. This event was called the tachonic aerogyny. And aerogyny is just a fancy word for a mountain forming event. Scene two is when Montpelier loses its beachfront. Did you know that Montpelier was beachfront property at one point? So scene number two is the Akkadian aerogyny, another mountain forming event. And then scene number three is all the little granite bubbles, all the volcanic that we have strewn about central Vermont. We'll talk about that too. Now it's always a good idea to get your bearings when talking about geology because we're talking about things that have happened over such grand timescales that it's really hard to wrap our minds around the the scale of it all. And so I love this figure because this basically takes a timeline of the age of the earth and it wraps into a big spiral so you can actually fit it in a slide. So the earth is 4.6 billion years old and that's right here in the middle. And if you unwind this all the way, we go three and a half, well actually we go four billion years before we get to right about here where the color starts changing. And this, I know you can't read this, it doesn't matter, it says Cambrian. The Cambrian era right here is where it starts changing color. And that's where we're gonna start our story is right here. The story of Vermont's bedrock geology as we know it starts here and it works our way towards the present. Another kind of background thing that is important for us all to be on the same page about is that earth's geology is a very dynamic thing. The earth is made up of tectonic plates that are kind of like jigsaw puzzle pieces that are floating in water, a sphere of water, right? And really there's floating on a sphere of magma, molten magma. And these puzzle pieces are being pushed and moved around all the time. Not very fast, about the same speed at which your fingernails grow is how fast these continents are moving around. But over the span of millions or even billions of years, these continents can really become reshaped and buried and exposed and changed and moved so that the earth's continents as they would be here in the timeline are gonna be totally unrecognizable to us now. So we're starting the story here 500 million years ago at kind of the edge of the spiral because if you go much farther back than that we just can't really keep track of what things look like because all the dynamic forces have kind of erased all the chaos has erased what was before. So I wanna share now a great video that is a diagram of the last 500 million years of geologic time. And let's cross your fingers that this works. This way. And would you mind hitting the lights for us there in the corner, Nona? Other side? Yep, perfect. Thank you. What's that? Sound is off. Yep. Oh, I don't want the sound on. Yeah, thanks though. Yeah, I'm gonna have the YouTube do the talking for the rest of the. So this is gonna be kind of as we know it the movement of our continents from 500 million years ago. This is really the story of Vermont's bedrock geology. So things are moving slowly here but I want you to find North America. We're kind of below the equator on its side 520 million years ago here. And you'll see that Vermont over here is underwater. We're not land yet. This is where Vermont would be but it doesn't exist yet right now. But this here is the tectonic plate that we sit on, Laurentia it's called. And what's gonna happen about 500 million years ago is this pile of volcanic islands is going to move towards the edge of Laurentia and slam into it. And when it does, there's gonna be this mountain range right here that starts to form and come into existence. See that? You just watch the green mountains form right there. But now what's gonna happen is it gonna be a quiet period for about 30 to 50 million years where nothing's really happening. We have this nice ocean out here that's getting narrower and narrower as this continent right here, this is kind of a proto-European continent called Avalonia and the tail of this continent is gonna come in and whack into the edge of Laurentia and kind of a multi-car pile up sort of situation here. And the forces of Avalonia kind of ramming into here are going to put the rest of Vermont in place. So everything east of the green mountains. So right now these green mountains are basically dropping off right into the water. And if you're sitting on top of Mount Mansfield, well one you'd probably be 20,000 feet in the air because this was a tremendous mountain range at the time. It's had 400 million years to a road, right? And as you looked off to the east for 400 million years you'd see this continental landmass coming towards you and slamming in to the edge of the continent. So watch for that. Brace yourself. So now we welcome Eastern Vermont and New Hampshire and Maine to New England. No, that's down here. The map projection is really weird to just show North America but Africa is actually down here and that has nothing to do with our story. It kind of wax into the south of Florida at some point. But really right now up in Vermont nothing's happening. We are landlocked or I should say we are far from the continental or from the tectonic plate boundary. So all this moving in everything that happens after this point in the history of Earth's plate tectonics are irrelevant to Vermont because it's happening way over there. We're no longer right at the edge, the active edge of things slamming into each other. We are landlocked with New Hampshire and Maine off to our east at that point. So things get pretty quiet here in Vermont. Meanwhile, the Southern Appalachians are forming and growing. All sorts of weird things are happening. This is, I'm just kind of zoom forward a little bit here. This is Pangaea, one of the supercontinents, most recent supercontinent where everything was kind of, I'd kind of long done to all the continents that kind of found themselves. But again, Vermont doesn't really care. It's kind of over here. It doesn't know that Pangaea's happening and all this kind of stuff, right? We are pleasantly in the midst of, you know, we're just out there in the middle of the continent. I'm gonna back up and just play that first bit again just so that you can see that again with some context now. And, and a shout out to, what's this fellow's name? Scotizzi out of University of Chicago and University of Texas Arlington who created this paleomap project. These great figures. So we have this island arc here. This island arc is kind of, think about it as like Japan, like the islands of Japan. These volcanic islands at the very edge of a major tectonic plate margin. And so this whole proto-European plate is coming towards Laurentia and it will slam into it. And this is the tectonic erogenous, scene one, okay? Now we have the greens and now we have this trough closing. The green mountains are eroding away now into this trough. And then Avalonia comes in and it scrapes that trough back up against the edge of North America. And we end up with our Eastern Vermont. I think the light blue is just shallow water, yeah. Yep, yep. And this is a great diagram at the large scale of seeing what's going on. If you were to hold up a magnifying glass it would be a little bit off of what's actually happening but it's pretty darn handy to show. At this point all this is happening around the equator. Yeah, yeah, so this is a very tropical, this is also 500 million years ago so we didn't exactly have forests and whatnot but it was around the equators, yeah. So I just wanted to show you kind of a cross-section diagram of that story basically happening. We have proto-North America over here, proto-Europe over here. These plates are converging. If we were over on the Eastern edge of New York we'd be on the shores of this Iapetus ocean looking at this volcanic island arc coming towards us here, forming the tachonic aerogyny. Now this is where things get interesting. So if you are standing at the shores of Lake Champlain let's say and you walk into the water you're standing in sand, right, you're at the beach but you know that the farther you walk into the lake the muckier and muckier and muckier it gets underfoot, right, that sediment size starts to get finer and gloopier and gloopier the farther you get into the lake where if you want a sample of really good fine lake clay you go out to the middle of Lake Champlain and you take a sample from there. The farther away you are from the shore whether it's a lake or whether it's the ocean the finer and finer the sediments are that are gonna settle there. So the sediments that are eroding off of North America, off of Laurentia into the Iapetus ocean are very different. Here, then down here. When we're near shore, at a place that's near shore we're looking at deposits of sand. We're looking at deposits, we're in a place that's very, has a lot of light penetrating so there's lots of life, there's lots of coral there's lots of invertebrates, mollusks with shells things like that, algae, diatoms lots of things that create limestone and limey stuff, right? The farther we get out here into the deep water off the continental shelf this is where things like silt and clay are depositing and it's so deep that there's no light penetrating there we don't really have much life out here. So as the millions of years go by sediment is accumulating off the shore that's eroding off of the continents and the sediment that is here is different than the sediment that's down here. These sediments are building up again over millions or tens or even hundreds of millions of years so the sediment can be piled miles and miles and miles deep and the weight of the sediment on top of itself plus the water in the picture here cements that rock together and lithifies it lithifies a word that just basically means to become a rock. So the sand is lithified into sandstone the limey stuff is lithified into limestone out here that mud is lithified into mudstone or shale is another word for that, right? And so we have all these sedimentary rocks layers and layers of it miles and miles thick that are forming over this time and when this island art comes in and slams into Laurentia it's basically scours and pushes all this rock up with it. Kind of I like to think of it as like if you are trying to plow a driveway and you push the plow into it it piles up this big pile of snow at the end of the driveway that is what's happening here where you have the North American plate that's sliding underneath and subducting beneath that should do it this way. Proto North America plate is sliding down below incoming European plate and it scours and pushes those miles of rock up in front of it. And so what we see is that over here this is the Champlain Valley has just been added to Laurentia now from all these rocks that were pushed from near shore and the green mountains as all this junk all the stuff that was pushed up from farther deep in the water and this volcanic island arc erodes away quickly and basically we're not very far from the ocean here Montpelier is basically sitting right in here and looking off into the Iapetus ocean. This is our bedrock geology map. Yes. Will you talk about sediment at that scene? Like what is it? Is it bits and pieces of different kinds of rock or is it some kind of material or did it? No, it's just sand, silt, clay and dissolved like dissolved calcium. Yeah, so it's all the stuff that's eroded off of the landscape into the ocean. So it's the same, you know the same stuff that's, you know that runs through any stream really is. Yeah, it's just, you know, sand, silt, clay. They're no animals with plants, right? So it's all... Well eroding off of land is all sediments of weathered, basically what was weathered rock. So the landscape, the rock of the continent is weathering and eroding into grains of sand and grains of silt and grains of clay which gets swept downstream into the ocean and then gets deposited out there. You're right that there isn't, you know there's not a ton of life yet on land. In the water at this point there is life and so near shore you do have a lot of coral reefs and that sort of thing. But yeah, the sediment is made up of weathered rock. That's coming off the continent. This is Northern Vermont, just for context. Montpelier is this yellow circle in the middle and here's Burlington right here, Colchester-Cosway, South Hero. So this is just Northern Vermont on this bedrock geology map and a huge kudos to our state geologists and the Vermont Geological Survey because they have it a lot harder than say like Kansas. If you look at the bedrock geology map out in other places, it's not this interesting. I would, I don't know this for sure but I might wager that Vermont has the like for its size has the coolest and most complex bedrock geology story of any six million acre chunk of this country. So we have the Champlain Valley over here and we have all this stuff is the Green Mountains. If you wanna go in Vermont and find some really good limestone or really good sandstone, you go to Burlington, you go to Colchester, you go around here. These rocks here are these rocks here, all these near shore things, right? When we go into the Green Mountains, we're looking at rocks that are metamorphosed mudstone that came from, well, I won't go too far back, but metamorphosed mudstone that came from way deep in the Apatous Ocean. And so this is mud that's been turned into shale and shale when you metamorphose shale, it, you call that rock either fillite or schist or slate depending on how much metamorphism it gets. I can talk about that later or tomorrow, actually. It'd be a good time to talk about that. But basically the rocks that we have in the Green Mountains are these deep water, really old rocks that are put up there by this Teconic Eradjani event. Yeah, Deb, they're huge. Yes, hold that thought for two slides. Yeah, maybe three slides. We're not there yet. That was just scene one. We're only at, so right now. Oh, so, okay, so this, all this rock here, the Green Mountains, what this looks like is this. Can we pop the lights back on, Nona, please? If you have a rock and you hold it up, or look around on the chairs next to you and if you see a rock, hold it up in the air. I handed out like 10 rocks. I know they're out there. All right, winner, this one. And I know there's gotta be more than this. Oh, that one, let's see. Oh, that's not it. Okay, so this rock that is basically the western half of Montpelier and throughout the Greens, it looks like this. It's kind of bluish, kind of greenish. It is called Schist or Phyllite, depending on exactly where you're standing. And it is a metamorphose mudstone. Its source are from ancient muds and clays that are accumulating in the deep water way out far from shore. This geologist called this formation the Moortown Formation. So Montpelier right here, the western half of Montpelier, all this beige stuff is this bluish green rock. So I'm gonna pass this around and convince yourself in this weird light that it's, or the lights that are soon to be off again, that this is a bluish greenish sort of rock. And maybe we can pass around this other example of it too. So these came from Hubbard Park. These, in fact, came from Erica's Field Walk last week. So if you are, and I'll explain exactly where these are, but if you are really anywhere in the left half of Montpelier, this is the rock that you'll find. What's that? Say it again. Yeah, so the Green Mountains, I mean, so, so the question was, how did the Green Mountains did, is the fact that this rock is greenish blue? Is that how the Green Mountains got their name? And I would like to think so. I think it's just because they're forested and green and that sort of thing. But the rocks, the rocks are, do you kind of have this greenish, bluish kind of hue to them? And Nona, would you put the lights maybe halfway down? Yeah, great. So these, you know, this is Greenmont Cemetery. It's a rock escarpment here. If you go anywhere around, most of Harvard Park looks like this as well. Here at the Nature Center, it looks like this. So greenish, bluish rock, kind of slabby. Let's hold that thought and kind of put a mental bookmark on what this looks like. Tomorrow we'll actually explore this. You'll get to see it up close. Okay. Now Deb's question, how big were the mountains? So these mountains were huge. The Green Mountains have had 500 million years to basically erode away and they're still this big. So these mountain ranges would have been the size of the Himalayas at the time that they were at their peak. And so at this time, after the Teconic Erogyny, Montpiler was sitting right at the shore of the Apotus Ocean with a giant Himalayan-sized mountain range just out back. So if you were to walk up to the top of Harvard Park it would be a much longer walk back then. And for the next 30 to 50 million years, nothing was happening. Montpiler was just enjoying itself here on the shore and things were eroding away. As soon as mountains formed, they start to erode back into the sea. And so while that Avalonia was kind of coming in and getting ready to slam into Montpiler, all of this was eroding away. In the same process we were talking about before, where this sedimentation happens, what's happening then too. So now Montpiler is right at the shore here. And all this near shore sediment is made up of everything that just eroded off of the green mountains. All those mountains that just got pushed back up, all the most easily erodable, easiest to dissolve minerals and rocks were the first things to kind of melt off of those and find their way back into the ocean. So a lot of the stuff that had calcium carbonate in it that was pushed up real high was the first thing to dissolve and wind up back in the ocean. So anyway, all these sediments here that then lithified. And then we had another, one of these mountain forming events. Where here we have the green mountains and that first volcanic island arc that slammed into us. Montpiler is here. And we have this trough of the Apetus ocean that the mountains are eroding into. A new sedimentary rock is lithifying. Then Avalonia comes in and scrapes it all back up against Montpiler. And now once that happens, if you're standing at the top of Hubbard Park looking east, you're no longer looking out into the Apetus ocean. You're looking out across eastern Vermont and way out in the distance you see New Hampshire and you see Maine. So here we are in Montpiler. Everything to the west is all kind of green mountain formations. Everything to the east is all the results of the Akkadian Erogyny. And these rocks here look totally different. They look like this, right? This is not greenish blue. These rocks are charcoal gray. They're black when they weather. They weather oftentimes it's like rusty orange color, right? They're really striking beautiful formation. And it's very variable. And it's really variable because remember all this stuff was eroding off of the green mountains into the Apetus ocean. And that was near shore and it was a very kind of chaotic time. One day you have a big landslide, it dumps a bunch of sand into the ocean. Next day something else happens and a big landslide happens over here. Then maybe nothing happens for a while and kind of clay just kind of settles down. So it's just a very dynamic environment near the shore of this eroding green mountain range. And as a result, the rocks that we get are also very dynamic. If you are standing at one part of this ledge here, you're looking at a rock that could be compositionally very different than 10 feet away because this is just a very active environment. The depositional environment when that sediment was first going down was very active. So Nona, thanks for standing there and doing the lights. Lights on please. Hold up your rocks if you still have them. Great. So I know there's more than that out there. But let's see. So you have the more town formation. Paige, you have more town formation. This here is the Wates River formation. This is the other kind of rock here. And we can pass these to you. Those are some more chunks of the Wates River formation. So you can look carefully and see that there's little bits of rusty bits in there but largely it's black, charcoal gray. Hard to see in this light here. So that's scene two. In scene three, oh yeah, sure. Oh, that's perfect lead-in. Okay, you might notice that there's these big red blobs all over. Is that what you're wondering about? Okay, so we have this really north-south running geologic map. You can just picture this being accordion together as a result of those mountain forming events. You understand now why everything is oriented north-south because of this dramatic pressure of the tachonic aerogyny and then the Akkadian aerogyny. And yet then we have these weird blobs of this orange-white dotted stuff from the map. That's the volcanic stuff. Yeah, so meanwhile, while this was happening with the Akkadian aerogyny, whenever you have a plate boundary that's subducting beneath another plate, that's an immense amount of crust that is being burned and melted into the mantle down below. And as that all melts, it creates an incredible amount of pressure. And so the magma that is being formed from this just melting into the mantle starts rising back up through the crust. And it's burning its way up through the crust towards the surface. It's really hot. It's really gaseous. It wants to kind of move upwards. And so it's just kind of melt. It's, as it melts, it kind of moves this way up like the bubbles in your soda, right? Through the earth. And if that magma makes it all the way to the surface, then we know that as a volcano. But more often than not, it kind of peters out before it gets there. As it gets closer and closer to the surface, it's cooling down more and more and more to the point where it's not really active anymore. It just kind of settles in place underground. And you end up with these little pillows or like balloons of magma that are beneath the earth's surface. Those are called plutons. And these are granite. Granite is the igneous rock that you get from this process. And granite is also a very strong rock compared to the limestones and sandstones and shists that we've been talking about. And so over the span of hundreds of millions of years, as the whole Vermont landscape erodes away into the ocean, it reveals these plutons that don't erode away as easily. And so granite is basically cooled magma. And any rock can become magma once you melt it. Yeah, thanks. And so these are both kind of heavy. Yeah, this is light enough to pass around. So here's a big hunk of granite. And if you look at this carefully, if you're willing to take that, thank you, Brian. You can, yeah, you can look at the crystals formed in there. Every granite outcrop, and we'll actually circle back to this in a moment, but every granite outcrop, every pluton has a different kind of signature of the size of those minerals and also the composition of them, the ratio of feldspar to quartz to mica or things like that. And so you can tell where a chunk of granite came from if you can match it to the chemistry of the surrounding plutons. So every one of these orange bubbles is a magma pluton that has, a granite pluton that has been revealed through erosion of everything around it. Yeah, Nona. It was magma pluton, but I don't know if you feel it. This microphone can hear it, and also you can hear that. So Nona was noticing that when you cross into a plain field, suddenly you end up in granite land, grottin' state forests, right? All that is all granite. That's what this big, all this big thing here is all grottin' state forests and plain field and whatnot. And it's a sudden transition because the edges of those plutons are very discreet. Now, why does it, is it a coincidence that the river happens to be the thing that delineates it? Now, I don't, without going there and looking at a escarpment on one side of the river and looking at it on the other, I don't know, but rivers tend to find contact points between geologic layers because those are point of weaknesses. And rivers, when they find a spot of weakness that kind of rode in there and then kind of like a knife through butter, it just kind of incises itself into a path that it likes. And so it could be that the edge of that pluton is just a nice space for that where that river kind of tucked into and has followed. Okay, so, quick act one recap and then we're gonna go on a tour of some sites in Montpelier here. Montpelier is at Vermont's geologic crossroads because we are sitting at a spot where everything to the western half of Montpelier is all one type of very old rock. Everything to the east half of Montpelier is a much younger, very different type of rock with a very different story. And we have these granite outcrops kind of not in Montpelier, but all around us that contribute to our story as well. Oh, I'm so glad you asked that because we're gonna ask exactly what I'm gonna do next. I'm gonna show you some zoomed in maps and I'm gonna do some zoomed in maps and then we're gonna go to a couple spots here. So first I actually wanna start with the orange bubbles and whatnot. You'll see that there's not a lot of orange bubbles right around Montpelier. If we zoom in to Montpelier here, this is actually that line between the more town formation, the weights of reformation that runs right through here, runs right through the middle of Hubbard Park. North Branch Nature Center is all more town formation, but if you actually go across like over the Vine Street Bridge, you're back in the purple stuff. If you're on Franklin Street, it's all weights of reformation. If you're over here at CCV, it's all more town formation and it's a sudden transition. But I wanna direct your attention there down here to this tiny little sliver of orange, right? Has anybody been there before? This is the north end of Berlin Pond, right there, cut off at the edge of the map. And if you go here, Nona, would you hit the lights please? Thank you. So north end of Berlin Pond, this is Crosstown Road that takes us down to West Berlin. Should probably use this. And then right here is the parking lot for Boyer State Forest. This is all Boyer State Forest and Irish Hill trails, Darling Hill trails. And if you park here and you walk in, you're walking in through all that weights of reformation, all the blue stuff, all that black rusty looking kind of slabby stuff. And then you hit this spot and suddenly you come into this little pocket of granite. This pocket of granite that's maybe three times as wide as this building and a few hundred yards long. And that's it, tiny little pluton that's been revealed. And it was known about because the West Berlin Granite Company set up shop here courying this tiny little pocket of granite for the span of about 50 years in the 1800s. And when you're here, you'll find these awesome little Cory pond here, spotted salamanders and Jefferson salamanders breeding here, FYI. There's little piles of granite tailings, of blocks that they cut out that broke. So all over there's these big rock outcrops of just granite tailings that porcupines and fishers are hanging out inside of this amazing place. And even if you haven't been here, you have been here. So this is State Street, the Episcopal Church on State Street. And this church was built from granite from that Cory. And so if you were to look up close at the rock, the granite that I'm passing around, it is going to be exactly the same as the granite up close on these stones on the Episcopal Church. So I wanted to start by talking about granite like this just because Montpelier has such an important role in Vermont's granite industry. This is a slide I grabbed from Paul's talk last week, so a courtesy of the Vermont Historical Society. But this is kind of looking down Stonecutter's way, taken from, would this be taken kind of near where Sarduches is right now maybe? Looking down that way. So there used to be a really active granite finishing industry along the Winooski River once the railway went in here in the 1850s. And so yeah, again, Montpelier doesn't have any granite but a lot of granite came through Montpelier and so as a result, a lot of buildings in Montpelier were able to benefit from that. Let's go back to the Episcopal Church. But has anybody walked around to the backside of the Episcopal Church? Fascinating. This is one of my favorite structures in Montpelier. Now the framing around the edge of this chimney here is our features of granite. You can kind of see that gray, these gray blocks, right? But everything else looks like bricks, doesn't it? But it's not brick. It's the Waits River Formation Bedrock. And it just so happens that stuff is nice and slabby when you crack it and break it, depending on if you're in the right spot in these formations, it breaks into a nice, flat thing that you can pretty easily make into something that you could make a really sturdy fieldstone foundation or stone wall or actually lay it like bricks almost in structures. So I haven't seen any other buildings in Montpelier that take advantage of this. Have any of you seen other places that utilize Waits River Formation rock in its construction? Certainly foundations. As I was wandering around Montpelier looking for this rock, I really wish I could have seen into the foundations of these buildings because I'm sure that most of the foundations in our city are either made from more town formation or Waits River Formation, depending on where you are. Does anybody have a stone foundation? Which one is it? Yeah, are you on this side or that side? So yeah, we're just, yeah, so you could actually have either right there. I should just say that this little purple stripe down here that's like 100 feet wide, that's kind of an intermediary zone of, basically it's like the Waits River Formation. It behaves very similarly. And I don't wanna, I'm just gonna wave my hands and just say let's not worry about that right now. Yeah. Yeah, that's a great point. That's actually a perfect segue into the next place we're gonna visit too. So thanks. Oh yeah, so that's the rock from the Episcopal Church, comparing that to the outcrop. We're gonna go here tomorrow too. This is at the bottom of Saban's pasture near the Pioneer Street Bridge. Oh, we'll come back to the river abutments in a moment. Let's talk about the Hubbard Park Tower. This is all more town formation. See the greenish blue? And there's other stuff mixed around in here. But the Hubbard Park Tower, right, this is the construction of this started in 1915. We had a railroad, so we could have had things that were brought into town to build stuff out of, but no one is carrying rocks up to the top of a mountain to build this tower. Instead they're dismantling the stone walls that were around the park and using those stone walls as the construction material for the tower. And so it's really fun to go to the tower and get a sense of what the local geology is like by just looking at the characteristics of these stones. You see, this is that more town formations, that blueish green rock, but we're looking at an angle of it that's really showing the metamorphic warps and things like that. As this rock heated and got pliable when the green mountains were formed, created these kind of ripples and whatnot. If you're, and one of the rocks that's going around, if you look head on at the rock, you can see these ripples too. It would be called either a fillite or a schist. Like we want categories for things in terms of names of stuff, like we want it to be either a limestone or a marble or a schist or sandstone. But in reality, you get these integrates between all of them because it totally depends on just how much pressure this spot got versus that spot right next to it. And so I love the mess of it all. It makes it easy to do a lot of hand waving. We have these chunks of quartz that form in gaps and fissures and seams in the rocks. When the mountains form and the rocks cool and you end up with big cracks and voids inside the rock, groundwater fills into those spaces and the silica that's dissolved in the groundwater precipitates against the edges of those voids and fills in over time. Kind of like if you put like a popsicle in a like a sugar water cup and you leave it there for a while, you'll get that like sugar candy popsicle. Same thing's happening underground, but it's silica forming in the voids and it forms these big quartz boulders, right? So a lot of more town formation all over the place in this tower. And some sides look more weathered than others. And some of these rocks might be coming from a little farther east into that purple, purple slice as well. But I don't want to be labor that point right now. Well actually what I will be labor though is kind of one cool thing is see how some of the rocks are very nice and rounded off. And some of them are nice and angular. So we have like a rounded rock and if this one is pretty angular, this one's pretty rounded. This is pretty angular, right? You can tell which rocks have been tumbled around by a glacier and which ones haven't by how rounded off they are. You know, this being underneath moving glacier we'll do that to you over time. So some of these rocks you can tell we're probably taken out of the soil that were till stones that were left there by the glacier and others were rocks that were maybe chipped off of a ledge or an outcrop nearby and then placed into place. So I invite you to scrutinize the tower next time you're there. National life parking lot, the weights river formation, the black stuff that rusts a little bit orange, right? Right across the river from that same spot is the more town formation at Greenmont Cemetery. And when you look up nice and close, you can actually see those metamorphic folds in some places of when this was hot and under pressure like taffy as it was forming in the greens. Backing up, this is what that formation looks like farther back and now you can really get a sense of that blue-green kind of tinge to this rock outcrop. Anybody here in 2005, see this happen? Off of Elm Street. So this is more town formation showing its weakness when it is aligned in a certain way where water can get down in there and freeze and thaw can crack things off and cause rockfalls. You're asking about why a house might be structurally unsound on a near a ledge of more town formation. This is maybe one of the reasons why. Yeah, it's straight out of the other side of the river. What's that? Yeah, it's right across the river from this spot, yeah. This is more town formation, yep, up Cliff Street and everything, yeah, yep. So back to our bridge abutment, our river abutment things, right? I love this spot because this shows the entire bedrock history of Montpelier in one spot. Let's zoom in on this. Can folks recognize where this is? Betnails Beach is the Lane and Street Bridge. Let's look closely. The bottom here, more town formation. On top of that is stacked slabs of the Waits River formation. On top of that are stacked slabs of cut granite and I wonder if you could do a timeline of the history of embankment and raising of this embankment based on what kind of rock is being used. Right across the river from that is, this is the other side, all big granite blocks here. I think they probably just used whatever was handy in lying around. So yeah, I mean, maybe just down the road somebody had a pile of this stuff lying around or they brought, there was a bunch of tailings of Waits River formation that they could bring over on a rail car really quick or something. So it was convenient, it was probably the only answer. So yeah. So now with your trained eyes, you can tell that the Bethany Church is weird. It's a beautiful church. I love the architecture, love it. But this ain't Montpelier Rock, right? This is Moncton Courtsite by the way from Burlington, Colchester area. This was built after the Montpelier Railroad got its spur into town. So finally at this point, once we got into the 1860s, you could build a building out of whatever you want because you can get rocks from quarries from all over the state to your city. Prior to the 1850s, you had to use what was lying around. So use that, so scrutinize the buildings that you see in terms of the rock that you see and you can maybe start to put some timelines on what you're seeing. I'll finish with this great photo by Wayne Fawbush that he posted on Facebook a couple of weeks ago of the state house. Now I think that the state house was cited where it is by geologists because if you were to pick a perfect spot to perfectly represent the entire story of Vermont's bedrock geology, you would put the state house right here because the boundary between the Moortown formation and the Waist River formation runs right across the middle of the state house lawn. If you walk out the western door of the state house, you are walking into Moortown formation. If you walk out the eastern door of the state house, you're walking into the Waist River formation. And I just think the odds of that are just so poetic. Love it. If you kind of go and get a sense of what it looks like over here and then go and compare to get a sense of what it looks like over there, you'll see the difference. Because it's actually in this weird purple zone, which is kind of messy, it's kind of hard at this spot to really see a clear slice between the two. But there is a place that you can see a clear slice and it's super satisfying. And that is, and maybe some of you know a different one than I do, but the place that I love is the northbound exit ramp into Montpelier. So let me take you on a trip there. So as soon as you get off the northbound exit ramp in Montpelier, notice the rock escarpment turning suddenly from the black Waist River formation immediately into the blue, green, and more town formation right there. So this is called the Richardson Memorial Contact, right? And I don't know why, but it has a name. And that is the spot where you put your finger on one side of that versus on the other side. You're spanning 60 million years of geologic time. One side of that, you're touching the rocks that were put there by the tachonic arogy. And the other side, you're putting the rocks that were formed by everything eroding into the ocean after that and then being shoved back up in the Akkadian arogy. Isn't that nice? Yeah. Yeah, sure. And look to see if I could find the spot because I was also intrigued by the Times-Argus article which actually talks about that state house location and I couldn't find a good reliable spot. So it's there, but I couldn't see it. But also the rocks were wet too. And so once things dry out and maybe in a different season it'd be a little more obvious, but we'll collectively keep an eye out for that. Becker, who was his first name? Larry Becker, wrote an article in the Times-Argus talking about basically talking about this, about how the state house happens to be in a really unique place geologically. It doesn't go into all the detail that I just bored you with, but does explain that these two sides are very different geologically and that the state house is this cool dividing line and suggests that you can go behind the state house to an escarpment right there and actually see that line. I didn't see it, but okay, well then I believe them, but I didn't see it. So collectively we'll go find the spot somehow and report back when you found it. So I want to get into our act two which is a shorter act than act one but very interesting as well. So we're gonna talk about the glacier junk now when the earth, where and when and why the earth is flat in some places. So we're going up a layer of our geologic landscape and we're also going way to the end of the spiral to this little gray blip on the very end, the last 20,000 years of the story of the earth. Now one thing that folks often get confused about when we think about geology, that hopefully I can just put to rest, when we talk about rocks and bedrock and mountain forming and stuff like that, we're talking about things that happened millions of years ago and processes that took millions of years to happen. When we talk about glaciers and sediment and sediment deposition, we're talking about things that happened thousands of years ago and took hundreds of years or even tens of years to happen. So different time scales entirely. So we're going much more into our recent past here. And we're gonna go to about 20,000 years ago at the peak of our last, our most recent ice age. And at this time, all of the northern part of North America was under this big ice sheet called the Laurentide Ice Sheet. And we were covered under that ice sheet for quite a while. Vermont was entirely covered by a mile thick ice up until about 14,000 years ago. And that ice, that glacier as it advanced kind of scoured everything. It kind of wiped the slate clean of everything that was above the bedrock at that time. Now I couldn't find a picture of what it looks like to be under a mile of ice, but I wanted to find at least a picture of a lot of ice to hopefully convey something. So this is maybe a hundred yards of ice and what things might've looked like at certain times when you're looking up the North Branch Valley or looking up Little River or something like that. But during the Glacial Maximum, the top of Mount Mansfield was under the ice. We were talking about a lot of ice. Now when glaciers start to melt and they start to retreat, they don't, you know, so glaciers actually advance and they push and scour things in front of them. But when they retreat, they don't turn around and like march back North. They just melt in place, right? They melt from the edges inwards. Kind of like you put a ice cube on a table and you watch it melt. Like the center middle of that ice cube isn't gonna, that's gonna be the last thing to melt, melts from the outside in. And so the edge of the Laurentide Ice Sheet retreated or receded to the North. And as that happened, river watersheds would be impounded by those glaciers. This is actually a place, this is a Google Earth shot from the Viedma Lakes in Argentina which is a really cool example of this process that happened in Vermont 14,000 years ago, happening today elsewhere. So we have this big glacier that's retreating out of this watershed. And as it's retreating out, this is the glacier up here, the glacier forms a dam that backs up a whole reservoir of water behind it. That reservoir is made of all the meltwater of that glacier as well as all of the rainwater and snowmelt and everything from the whole watershed here. And this lake will stay here and it fills up until the water can find a different outlet through a different mountain pass to escape from. But as soon as this glacier retreats far enough out, then this whole lake will drop down like pulling a cork, like pulling the plug in the bathtub, right? Now let's look at our landscape here. 14,000 years ago, Montpelier is right here at the E of Lake. There's the North Branch, North Branch, Little River, Mad River, Dog River. What's the name of this river? It's Jail Branch, down to Williamstown. Anywho, so this is a glacier like Wienewski that was formed by all of the glacier. So the ice had retreated out of the mountains, but there's still a vast amount of ice in the Champlain Valley that was acting like a big dam blocking up this whole reservoir of water behind it. Right at about... Lake Champlain is under there. Lake Champlain is under here, yeah, yeah, yeah. Yep. Montpelier right there. Yep. Yep. Here's the Worcester Range. So yeah, Montpelier. And yeah, so the Wienewski River, that all the water coming into the Wienewski River Valley could not drain out the Wienewski River into Champlain Valley. Instead, the water built up until I could find the next lowest mountain pass, which is here at Williamstown Gulf, at like 279 meters. So this is just another map of the same thing, Glacier Lake Wienewski. But then the ice retreated far enough out that the Wienewski River, that this was no longer the lowest point in the Williamstown Gulf, but instead there was a channel that opened up where the Wienewski River could get its way around the Huntington Gorge and out through Hollow Road into Heinsberg right here. There's a giant sand quarry right here in Heinsberg at the intersection of Hollow Road, and that's why. Because for a short time, the entirety of the central Vermont bathtub was draining catastrophically right out of here and running into Glacier Lake Vermont. So as the Glacier retreated up the Champlain Valley, there was another Glacier Lake that was formed that was being backed up behind it, where the flow to the north was being blocked by the ice itself. So like how fast did it happen? So this happened in like days. It was, I mean, however long it takes that much water to get out of there. Like this wasn't something that happened over the span of years and centuries. This is like, you don't want to be standing here. Like this was happening in hours or days, all this was draining out. So very catastrophic lowering, pulling the cork and the bathtub, right? And so then we ended up with this new lake level, this new step in the staircase of our Glacier Lakes, Glacier Lake Mansfield. And then the ice retreated far enough north that the Wienewski could no longer needed this outlet here, and it could instead resume its normal course into the Champlain Valley this way. And the lake level dropped again to a lower stage of Glacier Lake Vermont. Montpelier is, where are we now? There's a little river, so we're here. Yeah, this is the North Branch Valley. We are right there, right now, something like that. But this will make it easier. So here we are in Montpelier. We are up the North Branch, over there somewhere. This is Vermont Compost. This is, anyway, Montpelier, Terrace Street, Route 12 South, the solar panels behind National Life, like Child's Garden, right? Wienewski River. So here we are. This is what would have been underwater, Glacier Lake Wienewski. So this is just a short period of time, 14,100 years ago to 3,13,800 years ago. We'll be a test on that later. But no, this is like, so like for 300 years, Montpelier was inundated up to this level. About 900 feet in elevation. It varies depending on where you are, based on the rebound of the earth from the weight of the glaciers. I won't get into that. But importantly, today when sediment runs off of our mountains, it runs downhill and dumps into the North Branch or into the Wienewski River, right? So sediment works all the way down and it pours into the river and the river carries it down. But if you have a lake in the way, those tributaries come down and they dump their sediment wherever that lake happens to intersect that drainage, right? And so, and there was a lot less vegetation around at this time too. This was more tundra-like at the time. And so you have all this erosion, all this sediment running down the mountains. And as soon as it hits the edge of the lake, it dumps it out in place. So we end up having essentially like a bathtub ring of sand and gravel and sediments along the edges of our Glacier Lakes. And if you go to certain places in Montpelier, you can find those bathtub rings. But it's not just Glacier Lake Wienewski. Once that level dropped down one stair step, the lake level dropped down to here at a Glacier Lake Mansfield level for another 300 years. It stayed there at about 700 feet above sea level. And we get another series of bathtub rings there. Sediment that, now the tributaries can come down farther and they hit the lower lake level and they dump the sediment there. And then Glacier Lake Vermont dropped again. There are a couple of intermediate stages between these two things that I'm just for the sake of simplicity. Just know that they're there and know that as the lakes retreated, they didn't do it gradually over time. They did it catastrophically suddenly from step to step to step. And so we see stair steps of sediment in certain places. Now, this is complicated a little bit because we've had then 11,000 years of erosion happening that has obliterated and washed away and buried that evidence in most places. But there are some places where we can still see evidence of that, which we'll go into in just a second. In fact, we're going on that tour right now. So the first place we're gonna go is up to the edge of the Wrightsville Reservoir, just looking north from the dam because this is a good mental image of what it would have looked like back then. The Wrightsville Reservoir is at about 625 feet above sea level, so this is kind of between Glacier Lake Mansfield and Glacier Lake Wienewski in height. But if you imagine kind of looking north up the reservoir, this is kind of what the whole valley would have looked like. The whole all central Vermont would have been kind of looked like a big reservoir like this. But we are stopping on the dam because we're actually on our way over to Ananda's Gardens, okay? So we are in an incredibly hilly town, right? There's a lot of hills. There's a lot of mountains. There's a lot of uneven landscapes. When you find something that is flat as a pancake, there's a reason for that, right? And Ananda's Gardens is surrounded by hills, but it is exactly 701 feet above sea level and it is flat as a pancake. And I interpret that as where rivers are running into the shores of Glacier Lake Mansfield. And so all of this is depositional, the sediment being deposited into that lake. Like a big delta, like a big river delta basically, or a beach or a landslide. There's different variations on the theme of sediment hitting the edges of this lake. And then all the energy of that moving sediment drops out and so you end up with basically a big flat bench. But yeah, Sandy. We're gonna go down a little bit farther south. We're gonna take a turn up Bullduke Road and go to North Branch Cemetery. Has anybody been there? Bullduke Road? Flat spot. What do you think the elevation of North Branch Cemetery is? 701 feet above sea level. Let's go to somewhere else. We're gonna go now down here and up the Terrace Street area and we're gonna go up to like Dairy Lane, that area. Other than this hill I'm taking a picture from. Has anybody noticed that that whole area is very relatively flat? So we know that these flat spots, they grow cemeteries because it's easy to put graves in sandy soil. They grow agriculture like Ananda's Gardens because it's easy to grow crops there. They also grow neighborhoods really well, right? These flat spots. And so the Terrace Street neighborhoods here between 650 and 700 feet above sea level. Let's jump across the river. Now we're on Route 12 South. And what's the name of the neighborhood like down below Westview Meadows? Is there a name for that? You know what I'm talking about though? I don't know. I wasn't sure if there's a name like the Meadows for it or something like that. Is there a place name? No. Okay. Yeah. But you know where I'm talking about, right? So again, super flat here, right? 695 feet above sea level is this road. So now there are red herrings out there. There are places that you'll find them up here that happen to be flat at 695 feet or 700 feet. There are places there. So you can be thrown off. But it's uncanny that you find a lot of these spots right at the edges of Glacier Lake Mansfield. We can go to other spots. We're gonna go back up to Sander Circle now. So what passing on is up Horn of the Moon Road, Sander Circle. And now we find some flat fields that are right at the shores of Glacier Lake Manuski. We'll go higher up. Continue down the road to Jacobs Road. Actually, this is Gould Hill Road. Heading down towards the Nature Center this way. So heading west on Gould Hill Road. Suddenly it gets very, very flat here. This is right at the shoreline of Glacier Lake Manuski. So, yes, absolutely, that is one of them. And I figure that not everybody knows where Stephen Seats lives, so I didn't mention that one. But yeah, right up Gould Hill Road here, there's a perfect flat bench that is part of this story as well. Yeah, so just pull up Google Maps and just look around and see what you find. And I wanna encourage everybody, this is the beginning of a city-wide scavenger hunt to find more examples of this stuff because it's super fun. So now I wanna leave you with one last fun thing to think about in terms of Montpelier's glacial history. Montpelier is nothing if not a good place to go and look at bricks. We have a lot of bricks and a lot of brickwork. Brick is made of clay with a little bit of sand mixed in as aggregate. And just because the bricks are red doesn't mean the clay was red. The firing of a brick oxidizes the iron and it turns it red. So just because you have a red brick doesn't mean that the clay was red in the first place. Our clay around this area is all, it's clay colored, it's gray, right? And so I wanna just think through something with you, which is a lot of the buildings here in Montpelier were built long before the railroad was put in. And just like it's very difficult to move rocks very far, it's also very difficult to move a ton of bricks very far, at least enough to build big buildings. And so back before railroads were connecting us all, it was generally kind of the rule more than the exception that bricks were made from materials that were found locally, that were fired locally. Let's look at the Vermont Mutual Insurance building next to like between the theater and the post office. Building was built in 1826. If you look up close at the bricks on this building, they're just a mess. Look at that. See all the sediment and aggregate, particles of all sorts of different size in this, right? This is old brick. And also look at the shape of the bricks, right? Of all the ones that are facing kind of horizontal, the ones that are like spanners. Look at how they're all slightly different sizes. Some of them warp up and down. Some of them are rounded on the corners. These are handmade bricks that were made from local clay. Now we were talking about what happens to the edges of these glacial lakes, right? If you go out to the dead middle of these glacial lakes, that's where all the clay and the silt is collecting, right? It's down at the bottom of, remember, if we're trying to find clay in Lake Champlain, you go out to the middle of the lake and drop a core down there. Go out to the middle of Glacial Lake Winnieski and you are right over the top of downtown Montpelier. Has anybody been to Blanchard Park behind the Montpelier Senior Activity Center? If you haven't, it's a great little spot to go. It's only a couple acres. But that's this little hill right here. And that is a giant lump of clay. Now this entire area over, like all of downtown Montpelier would have been just wall-to-wall clay deposits, but the rivers over the last 10,000 years have cut right down through them and washed them away and eroded it away. So we don't see a lot of evidence of clay deposits right in downtown Montpelier because of the scouring effect of the Mauner Winnieski and North Branch. But we do have plenty of clay around to build buildings with. I don't know for sure that Blanchard Park, if the hillside of Blanchard Park was a site where clay was excavated from to make bricks to build the buildings in downtown Montpelier, could be. And I would love to know if anyone has more information on that because that would be super exciting to find out. But I think it's very cool that our brick buildings, our older brick buildings in Montpelier are built out of the Lake Bottom Sediment of Glacial Lake Winnieski. And so we are looking around downtown Montpelier at our glacial history around us everywhere. This is the Rialto building across from my capital grounds. And this is the brick there, much more consistent grain size, but still really irregular shapes. See how this brick is kind of bends upward here and these bricks are a little bit less, they're not super consistent. So these are again old bricks, but from a different clay source or different aggregate mix that was probably still local based on when this building was built, but not from the same place as the insurance building. How about the building that Bearpond Books is currently in? This is a zooming in on these bricks. Look at what these bricks are made up of here, right? Old building, messy brick, wild clay, right? Compare that, remember how we looked at the Bethany Church after all the rock stuff? Compare that to the skinny pancake building right now and look at the brick work here. These bricks are oil struck or water struck bricks. They are modern, they are made of clay sources, like extremely pure clay sources, much younger and much more modern, brought in from elsewhere. And so as you wander around downtown Montpelier looking for bedrock escarpments and whatnot, also be looking at the brick because a brick is not a brick is not a brick. The way that that brick looks can tell us a little bit about where that brick came from and whether it is from our place or whether it came from elsewhere. So last slide is just, I wanted to give a couple quick acknowledgements. I wanna thank basically all the geologists that have done all the hard work of making this sort of thing possible to know in the first place. Stephen Wright's been instrumental, George Springston, Margie Gale and everybody at the Vermont Geological Survey. I wanna thank Charles Johnson for some of the illustrations that I used from his Nature of Vermont book back in 1998 that was published. I wanna thank Walter Pullman over at UVM for some of the geology diagrams. Clara Dacey for that great watercolor. And of course the sponsors that made the place program happen in the first place here, Hunger Mountain Co-op, Ben & Jerry's Foundation and the Vermont Community Fund. So I invite everybody, well first to join me tomorrow on a little field walk. Again, where is that happening? Gateway Park. What time? Nine and noon. Underneath the interstate. Yep. Yep. So and whether or not you can come on that field trip, I encourage you to go on your own field trip and see if you can find some of this evidence. And again, this is the very beginning of the story. I'm really excited about this idea and I look forward to the community mind and eyes going out and seeing if we can uncover more evidence in this story here. So thank you everybody. Nona, would you hit the lights again Nona please? I have some time for questions. I'm happy to stick around if anybody would like to ask some questions. Well, thanks. Thank you. Yeah, yeah. Why does Granite come in different colors? Okay, so in Granite you have black stuff and you have white stuff. Sometimes you have pink stuff. So this is the black stuff is mica, the white stuff is quartz and the stuff that's also white is feldspar. And if you look really close and you knew what you were doing, which I admittedly don't, you can tell the difference between the quartz and the feldspar up close. But sometimes the feldspar is pink and not white. And so that gives you pink granite. And the proportion of the mica to the quartz, the potassium feldspar to the plagioclase feldspar gives you the overall kind of look and feel to that particular kind of granite. Yeah, so our berry granite quarries are white and black. We don't really have the pink stuff here in Vermont. Do we? They sell some pink. Oh really? Oh, so I don't know that. If they have pink, maybe it's from here. I have never seen the pink granite in Vermont, but I'd be excited to learn that it's here. Yeah. So I think that one's marble. Yeah, which is metamorphosed limestone. And without knowing, without looking at the map, I'm not sure the origin story of that marble per se. Sorry, in Bethel? Okay, okay. We do have great marble quarries down in southern Vermont. Okay. It looks like when you're driving in the interstate, it just looks so shiny and bright and pure. You know, my initial inclination was like, oh, that might be marble. But it wouldn't make sense for our, the story that we've been telling because it's not that far away and it is part of the same plutonic origin story. So for the marble, anyway, yeah. Yeah. Yeah. What's the source of that lime? Oh, that's a great question. It doesn't seem right. Yeah, so the source of the lime and the Waits River formation is the result of a couple of different things. So the Waits River, depending on who you ask, people have either called it limestone, they've called it marble, they've called it sandstone, they've called it limey sandstone, they've called it sandy limestone. My favorite was Sophie Veltrop with the Northeast Wilderness Trust. She calls it slime stone. I like that. But so that depositional environment was, so there's two things happening. It was near shore. So there was, you know, biotic life that was dying and stuff like that. So there was a biotic component to some of the sediments that were there. But also it's a plastic limestone. And so remember at this time, the Green Mountains were eroding away into the ocean. And the first step to erode off the Green Mountains was all the calcium-rich stuff because that's the most easily dissolved in, you know, in rainwater. And so you have all this calcium-rich sediment that's winding up in the ocean, near shore, amongst sand and silt and all kinds of other stuff in this messy, near shore, turbulent water. And that is kind of the sediment that all kind of became the weight-server formation. So it's the plastic influence from the eroding greens. It's some of the biotic stuff from it being a near shore environment. And the crazy thing about the weight-server limestone or weight-server formation is that you can go, you can walk 30 feet and you can find an area that's super, like, neutral pH soil with lots of calcified plants growing on top of it. And you go 20 feet away and you're looking at, like, Christmas fern and a hemlock tree, like something that's very nutrient poor. It totally depends, I love this, it totally depends on what happened that day 400 million years ago at the end of that tributary, what was dumped out into the water there. So this gets back to that geological determinism, right? Like, a bad day 400 million years ago tells you whether or not you have maidenhair fern or a hemlock tree today on a particular rock. Great. Berry? Yeah, I'll show you. Oh, where's Berry on the Bedrock Geology Map? I think I showed some pictures, okay, here we go. So Berry is all this stuff. It's little, right? But it's high quality, right? So, you can go to some of these plutons and you can't cut a block of granite out of it, right? Like, it doesn't work. It's not, you know, from a commercial standpoint, it's not, it's no good. Which is, I think, why the West Berlin granite company at that little tiny spot in Berlin didn't really quarry anything else because they ran out of rock that you could cut into good blocks. And so, you know, Berry is small but mighty in terms of its granite quality. You'll have to help me with this. That's, let's see, that would be over here, right? The stuff? This cluster here is Woodbury. Okay, yeah. Oh yeah, because this is like Worcester. Yeah. Well, this map, you know, if you just Google Vermont Geology Map, this will be the first thing that pulls up and you can, and it's extremely high resolution so you can zoom right into like your street and see exactly what's going on there. Yeah. Interesting. So, first I'm curious, raise your hand if you live in Montpelier. Okay, keep your hand raised if you have clay soils. Now raise your hand if you have sandy soils instead. So where do you live in Montpelier? North Street. So up high towards the edge of the Glacier Lakes, right? Right? Where the sandy stuff was being deposited. Does everybody else live? In the bowl. In the bowl? Next to the neighborhood. Bear with me one second. Claren, is that up terrace, like the terrace street neighborhoods? Okay. Things can change quickly. Yeah, yeah. And also, trying to just get a slide up here that will help explain both of these things. Okay, Nony, will you hit one of the two lights please? Thanks. Perfect. Okay. So, you can end up with sand on top of clay and if the clay gets washed off or if the sand then gets eroded away you're just left with clay. So, lots can happen over the 11,000 intervening years. But, remember, if let's say, okay, we're gonna go over to Claren to now, we're over here, right? So we are way out in Glacier Lake Winooski, we're way out in the middle of the lake here. The shore is way up towards Portal Road, right? And so over here, the first thing that's depositing on top of the bedrock is clay or silt or just fine sediment that a gardener would interpret as pretty clayy stuff, right? And then when the lake level dropped, that same exact spot is now much closer to shore getting much coarser sediments deposited directly on top of what was the clay stuff. So you can, and then as soon as, then when you go down to Glacier Lake Vermont, well now the tributaries are just running straight through this and now they're carving down through all that sediment that they just put in place. And so you can have a cross-section where you have different types of sediments depending on where you were in relationship to the various different edges of the lake. So the clay that you're seeing is probably clay from Lake Winooski, Glacier Lake Winooski, and the overlying coarse sediment has been sloughed off or something like that. Yeah, but I also have not dug like a test pit out in those neighborhoods so now I really want to. Go and check that out. And also point out that this whole field here is dead pancake flat. I tried to get a photo of that but I couldn't really find a good place to park and do that, but that field just up Terrace Street is a good candidate for Lake Winooski. Nona, can I trouble you again for the lights? Thanks. Well, we're just after 8.30 so I'll stay up here for a little bit, folks want to come up and ask questions and look at rocks and stuff but I do want to release those that are itching to go have their Friday night. Thanks everybody for coming and see you tomorrow. Class dismissed.