Talk:Drumlin

Glastonbury Tor

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)

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? — Preceding unsigned comment added by Kaszeta (talk • contribs) 12:56, 26 August 2004 (UTC)

Think global! Drumlins are not only found in the USA. — Preceding unsigned comment added by 213.236.117.2 (talk) 09:00, 4 October 2004 (UTC)

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 78.148.72.112 (talk) 13:12, 1 March 2008 (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, 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)

Picture of a drumlin

I've got a great picture of an Alaskan drumlin I made from a TM satellite image. How do I post a picture? 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)

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)

Accuracy for lengths

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 131.215.159.174 (talk) 06:59, 12 December 2007 (UTC)

Whale shape

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. 70.56.195.231 (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)

I have also added reference to the description of drumlin swarms as creating 'basket of eggs topography', the allusion being to the shape which a wet cloth would assume once draped over such a collection of eggs. cheers Geopersona (talk) 05:06, 21 June 2019 (UTC)

drumlin

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 94.197.30.124 (talk) 11:05, 8 April 2010 (UTC)

reference parked for later incorporation

Johnson, Mark D. (2010). "Active drumlin field revealed at the margin of Múlajökull, Iceland: A surge-type glacier". Geology. 283 (38). geology.gsapubs.org: 943–946. doi:10.1130/G31371.1. {{cite journal}}: |access-date= requires |url= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)

Dyke, A. S.; Morris, T. F. (1988). "DRUMLIN FIELDS, DISPERSAL TRAINS, and ICE STREAMS IN ARCTIC CANADA". The Canadian Geographer/Le Géographe canadien. 32: 86. doi:10.1111/j.1541-0064.1988.tb00860.x.

Shaw, J.; Kvill, D. (1984). "A glaciofluvial origin for drumlins of the Livingstone Lake area, Saskatchewan". Canadian Journal of Earth Sciences. 21 (12): 1442. doi:10.1139/e84-150. — Preceding unsigned comment added by Williamborg (talk • contribs) 23:01, 18 December 2010 (UTC)

64°39′25″N 18°41′41″W

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)

Bedrock drumlins?

Reference is made to some drumlins being made of bedrock - that seems curious. A drumlin-shaped feature might arise from erosion of bedrock but it is surely not to be called a drumlin any more than a dune-shaped piece of bedrock would be called a dune. cheers Geopersona (talk) 05:09, 21 June 2019 (UTC)

Etymology in the Introduction

The etymology of the -lin/ -ling suffix needs to be added. (It's quite interesting because drum is Celtic and -lin Germanic.) S C Cheese (talk) 19:04, 14 January 2022 (UTC)

Similes

@Geopersona: Please forgive this very belated (and I'm sure very irritating) follow-up question, but I noticed this edit from 2019 where you reverted my addition of a {{clarify}} tag and thought it merited further discussion. While you're right that there's only one way to make a spoon resemble a small hill (setting aside the question of whether that would be inverting the spoon, precisely), this is a simile that fundamentally begs the question: by telling the reader a drumlin is a small hill that looks like something when we make that thing look like a small hill, we tell them precisely nothing about what a drumlin looks like!

"Half-buried egg", meanwhile, is confusing for different reasons – the egg not being inverted, I imagine it sitting upright with the pointier end poking out of the ground, when I think we're supposed to imagine the egg lying on its side. This is complicated further by the first two images in the article, neither of which seem to me to feature anything resembling spoons or eggs. The U.S. National Park Service uses the egg analogy but also has The classic drumlin shapes is a hill that highest on its up-glacier end and tapers gently from there. Can we add something like this to the lead—ideally in place of these muddled similes, but I'd settle for alongside? Might we also move up the third image, which gives the best indication of what a drumlin looks like in isolation? – Arms & Hearts (talk) 16:48, 28 April 2023 (UTC)

Though I didn't add this piece of text to the article, I see when looking in their authoritative tome, that Benn and Evans are themselves quoting Menzies who it seems, wrote in 1979 that they are 'typically smooth, oval-shaped hills or hillocks of glacial drift resembling in morphology an inverted spoon or an egg half-buried along its long axis'. But maybe add the long-axis bit? I don't see a problem with it being described in the way that it is - is it not quite straightforward? The wording says it looks like ('is in the shape of') an inverted spoon, not as you say, 'like something when we make that thing look like a small hill'. If this description is good enough for some of the key people in this field and is written as it is in language that non-glaciologists can readily understand, then that seems more than acceptable to me as suitable for the article. Of course what would really help would be some better photos of individual ordinary drumlins which really bring home the shape. thanks Geopersona (talk) 17:45, 3 May 2023 (UTC)

I'm minded to request a third opinion to see whether I'm alone in finding this description confusing – I'm aware that no one else seems to have objected to it so it's obviously a possibility. In the meantime, what do you think about moving File:Drowned drumlin in Clew Bay.jpg to the top of the article as the clearest depiction, for the purpose of demonstrating the shape, out of the few we have? – Arms & Hearts (talk) 13:17, 11 June 2023 (UTC)

Response to third opinion request:

Hi all. Per WP3O: Before making a request [for a third opinion], be sure that the issue has been thoroughly discussed on the article talk page. 3O is only for assistance in resolving disagreements that have come to a standstill. The above is a good start to a constructive discussion, but not thorough as yet. Personally, I think further discussion is required before seeing a 3O. However, if you disagree, please re-list your request and I will leave it for another editor to review. — MaxnaCarta  ( 💬 • 📝 ) 04:20, 13 June 2023 (UTC)