Pre-Lab Lab A

How did glaciation lead to the formation of Lake Agassiz?

Glacial melt water pooled up along the ice sheet margin to form a large glacial lake

How do you distinguish sediment that was transported and deposited by ice from sediment that was transported and deposited by flowing water?

Glacial valleys often have long curved sediment ridges that intersect the valley's midline at high angles. River valley features, such as leeves or stream terraces, tend to parallel the river Water tends to sort sediment by grain size, while glaciers do not sort sediment at all.

What are the main differences between Recent Glacial Margin areas and Older Glacial Margin areas in terms of the processes responsible for their present land surfaces?

In recent glacial margins, there are well preserved records of ice movement, erosion, and deposition. Older glacial margins don't because rivers have had free reign to shape and drain the land surface

What is unique about the Driftless Area compared to the rest of the Upper Midwest region?

It is the only area not recently covered by flowing ice

Why does the number of lakes present in a glaciated area decrease over time?

Rivers are reworking the land. When the river melted, the land began to slowly rebound and this uplift increases the slope and speed of the river flow so that rivers can more effectively drain the landscape.

Why are there so few surface deposits left in the Canadian Shield area?

So much ice moved across the region and removed all surface deposits

Be able to explain how glacial processes contributed to the development of the Minnesota River Valley and the Upper Midwest 'Pinery'. What was the primary resource of each area from the perspective of 19th century Euro-American society?

The glacier from Lake Agassiz eventually overflowed the lake and the water escaped down what is now the MRV. Resource = soil The cold harsh conditions along the glaciers margin prevented angiosperms in the 'Pinery' (flowering plants) from spreading. Resource = wood

How can you tell the distinguish a valley carved by glacial ice from one formed by flowing water?

U-shaped valleys are formed from glaciers/ice. V-shaped valleys are formed from rivers/water.