 So, in environments where ice dominates the transport of sediment, deposition usually doesn't occur until the ice melts. The sediment that the ice is transporting is suspended in the ice because of its very high viscosity and its laminar flow behavior. And so it ends up as sediment only when the ice actually is removed, which happens during melting. So there are a number of things that happen and where that ice melts does a lot to determine what the characteristic of the deposits actually look like. Okay, so if we have a slope here and we have the glacier on it, it often has a steep front, because it's very viscous it can maintain that front, and then we have sediment in the glacier. Because it's a laminar flow and very viscous, the size of the sediment inside the ice is unsorted. It is a huge range in grain sizes ranging from that rock flower that comes from grinding the bits of rock together into giant boulders. Maybe some of them just sort of fell onto the ice from mountains below, and then some grains can also get plucked off the bottom and trained in the flow here. So we're starting with unsorted sediment, and if the ice just starts melting, all of that sediment just falls out of the ice. Now when the liquid water flows away, it can transport some of that sediment, but sometimes let's extend our glacier onto this flat area here, so we have grains of all sizes here. If you get a chunk of the ice just melting and the liquid water filters in, so this is the melt water, so it goes into the ground water, here, all of those grains just get accumulated in a pile, so this would produce a deposit where we have all sorts of grains in an unsorted mix. So if the ice just melts and there's no transport by water, liquid water, we get this unsorted mix and it's called the dia mictite. So dia is too mixed as class, as rock, when it gets lithified. So that refers what this means is that there's just this really, really huge range in grain size in the deposits. So often the water doesn't all sink into the ground and you end up with water flowing downstream and if you have the liquid water flowing downstream, you transport the grain sizes just on the flow speed and so the grain sizes become sorted when they're transported by the liquid water. So if you have very large boulders and a mix of cobbles that aren't small enough for the water to transport, what's left behind can be poorly sorted, but the grains that are actually transported in the turbulent flow, the liquid water, follow the deholstrom diagram and you end up with better sorting of those grains through time. In the next couple, a little bit later in the quarter, we're going to be talking about rivers and often the rivers that are associated with this end up being braided rivers because there's a very large number of large clasts. So just keep in mind that braided rivers are very common at the toe of glaciers. So sometimes the topography is such that the melting water from the glacier ponds into a lake and sometimes glaciers and ice sheets flow into the ocean. And so there's a significant difference in the depositional process between rivers and lakes and the ocean. And so in this particular, we have our glaciers here and all the sediment and one of the things that happens is that the lake water is always above freezing because it's liquid and so often the sediment just drops as the ice melts, the sediment just drops to the bottom here and you end up again with a diamactite. And often in this particular case, there's a big sheet of diamactite and if you can demonstrate it from a glacier, it would be called til, a til sheet. So til is the term that's often used for glacial sediment. And that geometry contrasts to what happens when the ice melts just in the zone here and a lot of times what it creates is moraines. And these tend to be more piled up zones of diamactite. And often they are influenced by the details of the glacial flow themselves. So one of the things that happens when the ice goes into the lake is it often produces icebergs and those icebergs can transport sediment from the glacier out into the middle of the lake. And in general, it's the same thing happens when you form the til sheet here, the stones from this just drop to the bottom of the lake. Now normally the flow speed in a lake is very, very low and so large clasts are not transported out into the middle of the lake. And so when you see say a cobble size clast that's sitting in the mudstones in the lake, ice rafted debris is one of the possible interpretations for that. So the other thing about these lakes is that the rock flower that's really common stays in suspension, but it also settles out. So you end up with a lot of clay-sized grains, but they're made up of the bedrock. So they're clay-sized lithic clasts as opposed to the clay minerals that form from the chemical weather. And I should label this as a dropstone. Sometimes they're called the lone stone and the reason for that is dropstone implies a process whereas lone stone is descriptive. And so the final thing that's really common in these settings is turbidates and that's because the rate of sediment accumulation is highest right where the ice is melting and the sediment can accumulate there and the slopes can become over-steepened and you commonly get turbidates. So we'll talk about the feces in a later video and I'll summarize these, the types of deposits that you tend to see. The key points here are that when the ice melts, because it's a laminar flow, it leaves behind unsorted sediment of all the grain sizes from clay-sized to boulder that the ice is carrying. However, as it melts it produces liquid water and that liquid water can transport the grains and sort the grain sizes out and you end up with deposits that are going to be emphases that are associated with, for example, braided rivers, lakes or marine environments with an inherited signature from the processes of transport within the ice. Thanks for watching.