 I'd like to share some photos with you about deposition in Antarctica and in particularly in this area called the dry valleys which are at the edge of the ice cap near the McMurdo station where there's actually a bare desert land that is accumulating sediment. So we zoom in a little bit. This is Ross Island which is an active volcano. There's this beautiful glacier that's coming out and onto sea ice and so this is all sea ice and you can see it broken up into icebergs here. This area is much colder than Greenland and there's very little open water. In the summer you can get some streams and rivers flowing as well as open water ponds and the sea ice can break up but in general it's much colder. So we have flown from McMurdo to several places in the dry valley, Pierce Valley here and Wright Valley here. I'm going to show you mostly photos from Wright Valley and the flight and it really is quite different from Greenland in that it's again mostly frozen over and there are no plants at all. So this is a view looking south from the McMurdo station where it's mostly covered in ice and snow. Particularly this was a spring photo. It's still quite cold. This is called the Ferrara Glacier so the ice cap is up in the clouds here and it's filling the valley all the way through here. There's in general less sediment because a lot of the ice is coming off the ice cap and it's not melting as quickly as it is in say Greenland. When you get into the dry valley areas the ice cap again is back in the clouds and the Taylor Glacier is visible here. This is Taylor Valley but the air is very dry and so the ice sublimates it basically goes from ice directly into vapor and so the ice is flowing down but most of it just goes up into the atmosphere. There are also alpine glaciers that are from snow that are collecting on the mountains on either side and as you can see in this close part it's pouring down over the mountain and it has a lot of crevasses and breaks up and then it freezes to form glaciers coming down and these areas in here and this one back here are lakes. They have liquid water but they're covered with meters of ice and that ice is permanent. The edges around them can melt in mid-summer in part due to the heat of sunlight being absorbed by the dark rocks helping melt the ice but they do have that permanent ice cover and you don't get the open water lakes that you see in Greenland. So this is Wright Valley it's really quite dry and this is taken in the summer and there's enough melt water and enough absorption of sunlight by the rocks that you get liquid flowing water so this is the Onyx River. It's really just a stream but it's the largest river on the continent of Antarctica and it's flowing down and to the left in this image and it has a typical river form with a meandering and sometimes a braided channel. It flows into Lake Vanda so this is a picture I took standing on Lake Vanda looking up. The Onyx River flows through here into the lake providing it with its melt water. One of the nice features about Lake Vanda is it shows that really nice U-shaped profile. So when this valley was carved out by glaciers and when glaciers flow down a valley they have a wide erosive basis. The flow fills a lot of the valley like we could see with the Ferrara glacier early on and thus they're eroding all along the floor of the valley which tends to make them wide and flat bottomed. When rivers erode the erosive power is concentrated right in the stream golly and so they tend to erode the most there and tend to get V-shaped valleys. The fact that this valley is still U-shaped even though the largest river in Antarctica flows through it shows that the river has very little influence on the landscape compared to the ice. So this is looking in the other direction and from up a plateau so this is the head of right valley. There's a little ice covered pond and this is the edge of the Antarctic ice sheet supported by bedrock mountains and ice flowing off the top and reforming as glaciers down below but not enough to still fill this valley. There might be some ice under the debris right here it has the morphology that looks a little bit like it's been flowing as if it had had ice in it. So obviously there's bedrock around the edges but a lot of this valley is covered in in glacial till that was deposited when the ice was last in this valley and that till looks something like this. There are large blocks that stick out but a lot of it is a smooth surface with grains that are sort of a class that are sort of fitted together and you'll notice that this this rock has a very strange weathering profile to it and it's been a long time since ice was in this area and there's been a lot of wind blowing and the wind reworks the sand and abrades a lot of these rocks and then there's extensive freeze saw cycling particularly in the summer when the rocks can absorb enough heat to have very large temperature changes from day to night and that breaks up the individual crystals and particularly in pockets where there's maybe a little bit more humidity or slightly different changes in the profile and you end up with these very irregular weathering shapes. So if we look at the ground in more detail the till we can see that it is poorly sorted. So there's a lot of sand in here this is a cobble size grain as these are as well and in places where the wind where the till is protected from the wind the the glacial flower and the sand are still between the clasts and that includes if you dig down onto those flat surfaces at all you'll find a lot of very fine grains. So there are also places where the sand accumulates and this is one of them this from the one ripple crust to the other down here is about three meters so nine nine or ten feet and this is actually in granule sized sand and then as the you go further up in the image which is also uphill the ripple size gets finer and the ripple wavelength is smaller the ripples are closer together and smaller and the grain size is also smaller and the wind gets funneled into this valley and the very fine grains are too small to be deposited in this zone here but a little further up on the valley wall the wind is a little bit less strong and the and the coarse grains don't make it up there and the fine grains can actually accumulate. So these grains were all once part of the till that he wrote it out from other places in the valleys. So this is going back into right valley and you can see that a lot of the pebbles on the top are flat and that's from the abrasion of the wind grains flattening them off but we do have a lot of the big rocks sticking out with some really beautiful amazing sculptures created by the freeze thaw and temperature cycling and thanks for watching