 Hameki cross stratification is found in fine grain sandstones that were deposited by a combination of waves and currents and in particular waves and currents created by storms. So Hameki cross stratification is really a diagnostic feature of a storm deposit. So the combination of waves and currents creates flow along the the ocean bottom that is changing directions very frequently through time. The fine grained nature of the sand means that it doesn't really form dunes and the flow directions are not usually consistent enough to form ripples. So what happens is the sand gets piled up into what we call hummocks which are these high areas and then the surface has swales or lower areas in between the hummocks. So then the flow switches directions a little bit with the change in currents and the geometry then changes and so you end up with for example a deposition here but erosion of some of the lamina in other places. So I'm going to use my eraser here to erase these lamina and then the new deposits would create a hummock and a swale in a new place. So what you see in Hameki cross stratification a lot of times are these areas with low angle truncations of the lamina here. So there's not a big change in the lamina direction typically but you do see these truncation surfaces. So the drawing down below is a three-dimensional block diagram and if you look at the lamina here you can see a little bit what I drew above. So this lamina is truncated by an erosion surface here but the lamina are continuous on the side over here. There's another truncation surface here and two more further down and so on the panel on the right here again is drawn a little larger you can see the truncation surface. So one of the main characteristics of Hameki cross stratification are what we call these low angle truncations. Another thing that that commonly happens is that the lamina pinch and swell. So if you look at these these two diagrams here in general the arrows show an lamina that are thinning and they elsewhere they may thicken. So we can see that in the diagram here where the lamina are in general thinner here and thicker over here. That's related to the dynamics of this deposition on these hummocks and swales. So a hummock is a little bit of a hill which in this diagram is represented in these white areas. You can see that there's upswing here and the stippled areas are lower and so the hills or the hummocks and then these low areas are called swales. You can look at examples of Hameki cross stratification and these are mesoprotosilip carbonates from India and there's a scale bar on the image left right here and those little dashes are each a centimeter long. So one of the things that you can see this is a surface of a quarry and there are these highs here which represent the hummocks and then their lows in particular the modern gravel has filled in a lot of the lows. In this area over here you really get a good sense of that difference between the highs and the lows. So this is what the seafloor surface looked like during the storm waves that created those sorts of lamina. The image on the right shows that the Hameki cross stratification in beds. So here lined in blue we have a lamina that comes up and it's truncated by this lamina that's coming down here. So this is one of those low angle truncations and then you can see that the lamina thickness here is much smaller for the same number lamina as it is over here. So this is the pinching and swelling of lamina laterally. You can see also in the next layer up that the lamina are making these mounds and there's a lamina that's coming in here which is probably truncated by this one above. And you can see again that the lamina are making these mounds which are the hummocks and the swells. So this is an example of Hameki cross stratification in sandstones. Thanks for watching.