|This is the talk page for discussing improvements to the Drumlin article.|
|WikiProject Geology||(Rated Start-class, Low-importance)|
The accuracy given for lengths of drumlins is subject to doubt. you do not measure the largest size of such a feature up to the nearest half foot. —Preceding unsigned comment added by 184.108.40.206 (talk) 06:59, 12 December 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 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)
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)
- We could still use a decent photo of a typical drumlin on this page - not a distant or half-eroded one. cheers Geopersona (talk) 07:25, 22 March 2012 (UTC)
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)
The Tweed valley in North Northumberland in england is an excellent example of a drumlin field. There are many other areas of the UK that contain drumlinised areas, mainly in the north though as glaciers havnt affected the landscape as much in the south of the country. —Preceding unsigned comment added by 220.127.116.11 (talk) 13:12, 1 March 2008 (UTC)
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: [] []
I will add Patagonia to the list of places with drumlins, based on this fabulous photo: []
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, seismology 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)
Can someone suggest a better shape than "whale shaped" I don't see whales in drumlins and I'm not sure that whales share a common shape. If whales really do have a common shape and drumlins do in fact substantially resemble this, then I stand corrected. 18.104.22.168 (talk) 08:30, 29 April 2008 (UTC)jawshoeaw
- I've swapped this for a more satisfactory reference to the shapes of inverted spoons and half buried eggs as per a reputable author. cheers Geopersona (talk) 07:22, 22 March 2012 (UTC)
In order to add to the drumlin page it may be worth adding a piece on how drumlins aid us in the reconstruction of former ice sheets???? —Preceding unsigned comment added by 22.214.171.124 (talk) 11:05, 8 April 2010 (UTC)
reference parked for later incorporation
Johnson, Mark D.; Anders Schomacker, Ívar Örn Benediktsson, Alessa J. Geiger, Amanda Ferguson and Ólafur Ingólfsson (2010). "Active drumlin field revealed at the margin of Múlajökull, Iceland: A surge-type glacier". Geology (geology.gsapubs.org) 283 (38): 943–946. doi:10.1130/G31371.1.
Can the direction of ice movement be determined from drumlin shape?
I am a geologist, but I work mainly with petroleum exploration. I can't find where it explicitly states how to tell the direction of ice flow by looking at photos of drumlins. I realize that glacial alignment can be easily determined, but that leaves the actual direction of travel a 180-degree guess without being at the actual location to look for other clues like which way is downhill, which cannot always be readily known from a photograph. If possible, how does one tell the direction of glacier movement from the differences in shape from one end of a drumlin to the other? Or are drumlins irregular/varied enough so there is no way to tell with reasonable certainty which way the ice was moving without having to use additional information? Thanks! Linstrum (talk) 11:25, 28 March 2014 (UTC)
Answer: in drumlin fields as in the Lake Ontario plain (NY State) the upstream side has gentler slopes and is streamlined, the downstream side is much steeper. Blauwkoe (talk) 12:50, 28 March 2014 (UTC)
Okay, got it! Thanks. I suppose a partial analogy between sand dunes and drumlins could be made, where the downwind side of sand dunes is the steep side while the upwind side of a sand dune is the gentle slope side; and with drumlins the side where the ice is moving away from it is the steep side and the side of the drumlin where the ice is approaching it is the gentle slope side. It would be interesting to compare flow dynamics between air and sand dunes and ice and drumlins. Linstrum (talk) 10:56, 24 June 2014 (UTC)