From: PO2::"stagerc@NORTHNET.ORG" "Curt Stager" 15-NOV-1995 00:49:36.11 To: Multiple recipients of list QUATERNARY CC: Subj: raised lake beds (again) Well, there certainly seems to be a lot of interest in these raised lake deposits; I got about 50 messages, both giving and requesting information! I hope you folks don't mind if I just send this collection of excerpts to everyone on the list; I'll never have time to respond to everyone individually. My apologies if any of these writers did not want their messages broadcast; please let me know if this was bad form on my part (I left out all non-electronic addresses, at least). Here's a selection: ------------------ There are plenty of those things in Saskatchewan and Alberta, in Canada, that is, and in North Dakota, principally on the Missouri Coteau. They are called "perched lakes". Morphologically they represent high ground with glaciolacustrine rhythmites forming the bulk of the sediments generally collapsed at the edges. They formed on the surface of stagnant ice masses which already had a layer of debris, minimum thickness around 2 metres, protecting the ice from rapid melt. Such a debris can hold a lake with temperatures as high as 17 degrees (Celsius, that is) above stagnant ice. See publications by Sam Tuthill, Lee Clayton and many others. I had supraglacial lakes in my thesis area in SW-ern Saskatchewan, situated just north of the Cypress Hills. Peter P. David E-mail = david@ere.umontreal.ca ----------------------- From: book@tele.su.se (Thomas Book) I am not familiar with those deposits in southern Sweden, but I have heard of interstadial deposits (lake?) in northern Sweden - called "Veiki - moraines". They are described by Lagerback (or Lagerbaeck), Robert in Boreas Vol.17, pp 469-486, 1988. -------------------------- A quick check after my previous note uncovered the following: Gravenor, C.P. and Kupsch, W.O. 1959. Ice disintegration features in western Canada. Journal of geology, v. 67, p. 48-64. Clayton, L. 1967. stagnant-glacial features of the Missouri Coteau in North Dakota. North Dakota Geological Survey Miscellaneous Series, v. 30, p. 25-46. Dean Wilder Dean_Wilder@uwlax.edu --------------------------- Not exactly what you asked for, but take a look at: Florin, Maj-Britt. 1970. Late-glacial diatoms of Kirchner Marsh, southeastern Minnesota. Diatomaceae II - Friedrich Hustedt GedenkBand. Beih. Nova Hedwigia 31: 667-756. Florin, M.-B. and H.E. Wright Jr. 1969. Diatom evidence for the persistence of stagnant glacial ice in Minnesota. Geol. Soc. Amer. Bull. 80: 695-704. Florin argues that their were superglacial forests creating soils (with diatoms), and that these soils are dropped into lake basins where thay are found during recent lake coring. John C. Kingston ---------------------- There are not many articles on these features. All of the ice margins in the Des Moines lobe of Minnesota (my study area) are characterized by broad zones of ice-walled lake plains and other supraglacial landforms. This just means that the ice stagnated. I use a Midwest Friends of the Pleistocene guidebook article as the definitive reference. Lee Clayton, the author, wrote a short summary paper on the topic also . The Swedes call this Veiki moraine and Lagerback has an article on the topic. Clayton, L, 1967. Stagnant-glacier features of the Missouri Coteau in North Dakota. In Clayton, L., T.F. Freers, eds, Glacial geology of the Missouri Coteau and adjacent areas. North Dakota Geological Survey, Miscellaneous Series 30, guidebook for 18th Midwest Friends of the Pleistocene. Clayton, L., 1964. Karst topography on stagnant glaciers. Journal of Glaciology, 5., 625-656. Clayton and Cherry, 1967. Pleistocene superglacial and ice-walled lakes of west-central North America. (same guidebook as above) Lagerback, Robert, 1988. The Veiki moraines in northern Sweden - widespread evidence of an Early Weichselian deglaciation. Boreas, 17, 469-486. Note: this last paper has a lot of references in it. Carrie J. Patterson ----------------------------------------- I have been mapping soils in northern Michigan for the past 14 years and repeatedly encounter lacustrine deposition overlying glacial drift. Primarily we find sediment from glacial great lakes Algonquin (several stages are recognized) below certain elevations depending on position on the uplift curve. Currently in Alpena we are recognizing a landform we call "till floored lakeplain" that occurs adjacent to two eskers where the ice cave apparently widend during meltout and became inundated with proglacial lake water. There are also scattered areas of proglacial lacustrine deposition. Confirmation of the elevation of lake shorelines can be found on the landscape by locating deltas that form at the point where glacial drainage channels enter lakes. There are several excellent examples of this in Cheboygan, Montmorency, Alpena, and Alcona counties, Michigan. If you need some references you may want to search the literature for the works of Richard Futyma, Curtis Larsen, Leverett and Taylor (1915), and Wendy Burgis. Larsen has several papers. Thomas Williams ------------------ I've seen many of these features, both in Sweden and elsewhere; they seem to be reasonably common in areas of rolling or hummocky topography (including topography where the undulations are bedrock-controlled). I've written up one in Geologiska Foreningens 1989 v 111. There are a wide range of features and sedimentary successions that are associated with these ... Given that the ice advanced either uphill or parallel to the slope of the northern Adirondacks it seems quite likely that supraglacial ponds would form and that sediments would be preserved. Norm Catto ------------------------ Several possibilities come to mind. 1) As the ice moved from the north it plowed some debris into a hardpack layer known as lodgement till. This is usually a relatively thin layer of dense material. Then during retreat, as the ice front moved north, there were often lakes trapped infront of the ice either by debris dams to the south or possibly remnant pieces of ice. As you might know, the Champlain Valley contained a much larger lake during ice retreat known as Lake Vermont. Subsequent deposition left lake beds that can be found on till in places. 2) This also occurred in the uplands in environments known as high level lakes trapped behind dams as noted above. It seems logical that during retreat of ice lobes that ablation till (dropped out of melting ice) could be the first layer deposited and then as a lake advanced up a valley against the front of retreating ice lake beds could be deposited on top of the till. Laurence R. Becker, e-mail larryb@anrimsgis.anr.state.vt.us --------------- From: Richard Hammond We have abundant "ice walled lake plains" here in South Dakota. They occur on the Prairie Coteau and Missouri Coteau, two high plateau-like features in the eastern part of the state. These areas are nearly completely covered with stagnant ice features. The lake plains are commonly 1 to 5 kilometers in diameter. They are theorized to have formed over voids or portions of voids eroded or melted into the base of stagnant ice. The overlying ice mass then collapsed, forming a depression on the ice surface that became a lake "walled" by the surrounding ice. They are normally sub-circular to ovoid in shape and commonly exist today as elevated very flat-topped features about 15 to 50 meters above the surrounding drift plain. Lake sediments, often varved, usually make up a fair thickness of the sediments. A few Jukulhlaup fans have marked instances of the catastrophic draining of some of these basins. I am sure that there are other explanations for these features. I have not studied in the coteau area for a few years, and the scenario that I described above was worked out many years ago. ------------ From: John Reid One paper on perched lake plains is in: Clayton, Lee and Cherry, J. (1967), Pleistocene superglacial and ice-walled lakes of west-central North America: North Dakota Geol. Survey, Misc. Series 30, p. 47-52. Clayton (now at the Wisc. Geol. and Natrual History Survey, Madison, WI) wrote quite a bit on this topic. ---------------------- Thanks once again for your responses and you interest. Regards, Curt Stager.