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Drumlin Formation in Iceland

Jamie,

I'm really excited to follow your expedition! It sounds so exciting. One question: How is a drumlin different from a moraine?

Thanks!

Mike

Thu, 03/28/2013 - 09:41

Jamie Esler

Hi Mike!First, thank you for all of your help and guidance throughout training
this week. Your tips and advice have been highly valuable. :)
As for drumlins and moraines, they have both similarities and differences.
Similarities: they are both composed of till; a non-sorted sediment
that is deposited directly by the glacier itself.
Differences: moraines (and there are many types of moraines, so I will
focus only on terminal moraines here) form at the terminus, or end, of
the glacier. This area is known as the zone of ablation. Terminal
moraines form in long lines that run parallel to the shape of the
terminus of the glacier, and are deposited in a "conveyor belt" fashion
by the ice. Drumlins, however, form at the base of the glacier, hidden
from view and direct observation. They only become exposed for
observation once the terminus of the glacier has receded enough to
expose them. How they are formed...???? THAT is what our research team
is hopefully going to figure out.
Stay tuned...hopefully it will not be too long before the last part of
that question can be answered.... :)
Til Next Time,
Jamie

Mon, 05/06/2013 - 20:11

Anonymous

Hey Jamie, Are there any drumlins in our area? I was just reading a book on the glacial floods around here plus spent the weekend near Kootenai Lake and we have such a rich and interesting glacial history. Your summer expedition sounds great! Pam

Mon, 06/10/2013 - 05:37

Jamie Esler

Pam,Great question.
During the last Ice Age, a long tongue (called the Purcell Trench Lobe) of the Cordilleran Ice Sheet extended south from present day British Columbia into North Idaho. This lobe was confined in the Purcell Trench by the Northwest Rockies forcing it to behave more like a valley glacier than a continental ice sheet. See this link to get a look at the map illustrating this: (http://geology.isu.edu/Digital_Geology_Idaho/Module13/mod13.htm)
While ice sheets share some similarities with valley glaciers, they also have some rather important differences in how they move and the landforms they leave behind. Drumlins are characteristic depositional landforms of ice sheets, for instance, and are observed today throughout much of the upper midwest in Wisconsin and Illinois and the northeast in parts of New York.
Hence, there are no observed drumlin fields in North Idaho. The closest ones I can find to us on geologic maps are where the Cordilleran Ice Sheet was not confined into valleys: to the east of the Rocky Mountains in present day Calgary, Alberta, and to the west near present day Grand Coulee in Washington.
-Jamie