 So turbidites are a really interesting example of how we can use species to understand sedimentary processes and deposits. So turbidites are rocks, the height is the rock part of it, and they are often deposited on top of mudstone, and ideally in an ideal turbidite the base of the sandy part of the turbidite is often an erasional surface. So it might have some topography on it relative to the mudstone. Then the bottom of the turbidite can have some pebbles, sometimes even ripped up bits of mudstone. You remember from the Holstrom diagram, consolidated mud is very difficult to erode, but it can actually be pulled up into pebbles. And then so you have pebbles and coarse sand, and generally if you go upward in a turbidite the grain size decreases, so we would say it's finding upward, and this lower part usually doesn't have any sedimentary structures in it at all. So we call it massive. And then it gets to a point where there's very strong planar lamination, it's still composed of sand, you usually lose the pebbles at the base as it finds upward, so you end up with a planar lamination, and then as you further up you start getting ripple cross lamination. So those are my erasional bounding surfaces with a cross lamination here, and these are the cross lamina themselves, and I should specify that these are current ripples, is that they're showing flow in this direction the way I drew them here, and sometimes you can even get the crest of the ripple preserved, sometimes you don't, I'll draw some in here, we'll say that one gets eroded off, and then the grain size is still decreasing, so just decreasing all the way up here, and then you tend to get some fine sand in planar lamination again, but it's not as well defined, planar lamination, and this down here, and then you start getting, the sand size gets fine enough that it consists of silt, and again the silt has a faint planar lamination, so the grain size here would be very fine sand, and then silt, sized grains, so silt, the symbol for silt is this dot dash pattern, but it's hard to show both that and the planar lamination, and then there's a gradation back up into mud stone at the top, so I'm going to add faint to this other planar lamination, this planar lamination in the lower part here is very strongly developed, okay, so we can use two of the concepts that we've been working with in class to understand the flow and the variations of flow speed that might cause a termite, so the two things that we can see are we have a decreasing grain size upward, and upward is through time because we have the older on the bottom and the on top, and then the second thing that we see is the sequence of sedimentary structures, we have ripple lamination and planar lamination in these two areas, and a consistent interpretation with our changing grain size would be that this is an upper planar lamination, and as it's slowing down, you start developing ripples on top, so the sequence of sedimentary structures are consistent with a decrease in flow speed through time, so all of you do the arrow down for that, okay, so we talked about this, and then we have this mud stone that's accumulating as well, and we know from the Holstrom diagram that the flow speed has to be incredibly low for mud size grains to accumulate, so we can actually add a third point that the flow between seamstones is very low to get that mud stone, thanks for watching.