Talk:Drumlin

I've got a great picture of an Alaskan drumlin I made from a TM satellite image. How do I post a picture? [[User:timbabwe}timbabwe]] 2:12, 2 June 2007 (UTC)

• What's your basis for calling that a drumlin? It appears to me to be a bedrock-controlled feature that has an elliptical shape. On the topo map of the region, I don't see any drumlins. --orlady 11:38, 2 June 2007 (UTC)

Is Glastonbury Tor in Somerset a drumlin, you geologists? Wetman 19:52, 8 Feb 2004 (UTC)

Is it radially symetrical? It is described as conical, which would not be a drumlin shape. Drumlins are elongated (see drumlin field). I wonder if the whole mound is a human artifact? There are such mounds in Ohio and other places in the US. Pollinator 05:35, 9 Feb 2004 (UTC)

Try www.google.com "Glastonbury tor map" The tor is steeper at one end, more tapering at the other, and highest at the steep end. definitely more teardrop than "conical' which you read all the time. It rises out of the low rolling landscape, onces fenny, now drained, like a... well, like a drumlin. Wetman 05:49, 9 Feb 2004 (UTC)

I did some looking around sites on the Internet, and it does not sound like a drumlin. Here's one description of the geology: [[1]] Try a search for "Glastonbury tor geology" for more Pollinator 06:25, 9 Feb 2004 (UTC)

Excellent! not a drumlin after all. This link goes to the Glastonbury Tor entry! Thanks. Wetman 06:41, 9 Feb 2004 (UTC)

Its a syncline, a layer of harder rock has been folded by compressional tectonism forming a bowl shaped depression. An antecedent river (a river older then topography) has breached the wall of the anticline at the 5 o'clock position. Antecedent rivers and extensive erosion like this take several million years. It is unlikely to be in Alaska, though I'm happy to be corrected, Alaska was eroded by glaciers a just 12,000 thousand years ago. I'll put it on the syncline page. --Diamonddavej 18:47, 12 October 2007 (UTC)

Drumlin locations

I added Minnesota to the list of places with Drumlins (there is a huge field of them, the Wadena Drumlin Range, in the southern part of the state), but instead of listing a bunch of states, perhaps a reference like "upper midwest" would be better?

Think global! Drumlins are not only found in the USA.

D'oh! I'll see what I can do about re-writing this so that it isn't so US-centric. -- Kaszeta 13:51, 4 Oct 2004 (UTC)

Drumlin origins

The content of this page seems to have been influenced by a website that seeks to support creationism/catastrophism by emphasizing the "catastrophic flood" aspects of some scientific papers on drumlin formation. A more balanced view is desired. Some possible contributions toward that more balanced view: [[2]] [[3]]

I will add Patagonia to the list of places with drumlins, based on this fabulous photo: [[4]]

Orlady 5:46, 7 Mar 2005 (UTC)

Its common for creationist take an element fact and twist that fact it beyond credulity. The latest thoughts on Drumlin formation (I'm an Irish geologist, we named them and the best are here in Ireland), they formed towards the end of the last ice age when climate rapidly warmed. The higher temperatures caused the base of glaciers (~1 km thick) to melt and the water generated lubricated the contact between the glacier's base and the boulder clay/bedrock below. As a result of lowered friction, within several decades the glacier flowed into the sea. The rapid motion caused the boulder clay at the base of the glacier to form ripples. Drumlins are aligned in the direction of ice flow. I'll look for a few good modern references.

I recall attending an excellent lecture by a scientist from the British Antarctic Survey a few years ago, they are using seismometers and ground penetrating radar to watch, in real time, Drumlins form under the ice-cap of the antarctic. Its amazing, one month there is a great big hill of gravel (100 metres hight) but the next month its gone! Its a highly dynamic process. As for the Antarctic drumlins, they are not caused by climate change (well not yet). The glaciers move over bedrock with a higher geothermal gradient - the rock is warmer, this heat melts the glacier's base reducing friction. Oh and the other fantastic thing, the ocean tides >100 miles away affect the motion of the inland glaciers. High tides float glaciers at the coast causing glacier inland to episodically move towards the coast. The origin of Drumlins is known beyond doubt. --Diamonddavej 19:44, 12 October 2007 (UTC)