12 June, 1998

Hi everybody!!

Well how exactly do you do the kind of field work that Meredith and Brenda do? One of the important tools for a field geologist is aerial photographs of the area in which you will be working. In Antarctica, these photos are taken by the US Navy and provided to geologists. Aerials give you a big view, the birds eye view, which is impossible to get while you are there on the ground. After some practice of looking at the photos you can figure out t the places you want to investigate. Then you attach some pieces of vellum - a kind of fancy, heavy duty tracing paper on top of the photo. You map out the sites to study. When you get to the valley, you use the maps to guide you to those interesting places. If you decide that it will be worth sampling in an area, you mark the location on the vellum over the photo. Out in the field you dig a pit and sample, putting the rocks in a bag that has the same location number as the one marked on the vellum so that when you get back to your lab you can study it.

This is what Meredith Kelly is doing in the sedimentation lab at the University of Maine at Orono. She looks for evidence of ventification (sharp edges and indicates long exposure to the persistant Antarctic winds), desert varnish, a mineral deposit on the rock surface that also indicates long exposure. See the pictures!!

She also uses the shaker to separate grain size mechanically. (see the picture) Each of the layers contains a screen, and the sample of rock is placed in the top layer, the lid is closed and then we shake shake shake! Because the column of screens is stacked with screens that go from large to very small, the sediment is mechanically separated into sizes. Meredith also used the sediment settling tube and an Xray diffraction technique to minutely analyze the sediments from her field area. She will use this data to more completely describe her field area and use this data to support parts of her thesis.

Another thing that I learned today is that there is a big difference between what a temperate glacier does and what a polar glacier does. Hot Ice and Cold Ice! Temperate glaciers deposit the kinds of formations that most of us think about when we think of glaciers - things like drumlins, eskers, kames. These require warmer temperatures and running meltwater. Polar glaciers do not form these deposits, they are just really cold!! Thus we have another clue for teasing out past climate.

That's all for today!!