Glacial Geomorphology of the Last Irish Ice Sheet

Author(s):  
Robert T. Meehan
2011 ◽  
Vol 7 (1) ◽  
pp. 409-428 ◽  
Author(s):  
Victoria H. Brown ◽  
Chris R. Stokes ◽  
Colm O'Cofaigh

Finisterra ◽  
2012 ◽  
Vol 47 (93) ◽  
Author(s):  
João Bessa Santos

The northern sector of the Kent Interlobate Complex, created by twomajor ice lobes of the Laurentide Ice Sheet during late Wisconsinan times, dominates theglacial landscape of northeast Ohio. The geomorphology of this impressive complex revealsthe presence of large hummocks, kettle lakes and substantial esker chains. The esker chains,usually smaller than 1.3 km long, run parallel to the interlobate complex geographicorientation of northeast-southwest. Gravel pits present on large hummocks display beddedand sorted sedimentary units of gravel, sand and gravel and climbing ripple laminated sandwith folds, which demonstrate that the northern sector of the interlobate complex isprimarily a glaciofluvial feature. Topping these hummocks is a massive clast-supporteddiamicton interpreted to be a debris flow. These geomorphic and sedimentary characteristicsseem to indicate that hummocks present in the interlobate area are in fact kames and that theentire northern sector of the interlobate complex is a product of late Wisconsinan timetransgressive ice stagnation that occurred between two major ice lobes.


1999 ◽  
Vol 28 ◽  
pp. 67-74 ◽  
Author(s):  
Chris R. Stokes ◽  
Chris D. Clark

AbstractIce streams are critical regulatory mechanisms in contemporary ice sheets. It has been inferred that they also had a significant effect on the dynamics of former ice sheets. Subsequently, many people have invoked their widespread occurrence from a variety of formerly glaciated areas. Hypothesised locations, however, have often outweighed meaningful evidence. This paper addresses the problem, using the characteristics of contemporary ice streams as a basis for their identification from former ice-sheet beds. A convergence of knowledge gained from contemporary ice-stream research, coupled with theories of glacial geomorphology, allows several geomorphological criteria to be identified as suggestive signatures of ice-stream activity. It is envisaged that the geomorphological criteria developed here will introduce a more objective approach to the study of former ice streams. The criteria are used to construct conceptual land-system models of the beds of former ice streams, and it is hoped such models can provide an observational template upon which hypotheses of former ice streams can be better based.


2020 ◽  
Author(s):  
Bethan Davies ◽  

<p>We present PATICE, a GIS database of Patagonian glacial geomorphology and recalibrated chronostratigraphic data. PATICE includes 58,823 landforms and 1,669 ages, and extends from 38°S to 55°S in southern South America. We use these data to generate new empirical reconstructions of the Patagonian Ice Sheet (PIS) and subsequent ice masses and ice-dammed palaeolakes at 35 ka, 30 ka, 25 ka, 20 ka, 15 ka, 13 ka (synchronous with the Antarctic Cold Reversal), 10 ka, 5 ka, 0.2 ka (synchronous with the “Little Ice Age”) and 2011 AD. At 35 ka, the PIS covered of 492.6 x10<sup>3 </sup>km<sup>2</sup>, had a sea level equivalent of ~1,496 mm, was 350 km wide and 2090 km long, and was grounded on the Pacific continental shelf edge. Outlet glacier lobes remained topographically confined and the largest generated the suites of subglacial streamlined bedforms characteristic of ice streams. The PIS reached its maximum extent at 33 – 28 ka from 38°S to 48°S, and earlier, around 47 ka from 48°S southwards. Net retreat from maximum positions began by 25 ka, with ice-marginal stabilisation at 21 – 18 ka, followed by rapid deglaciation. By 15 ka, the PIS had separated into disparate ice masses, draining into large ice-dammed lakes along the eastern margin, which strongly influenced rates of recession. Glacial readvances or stabilisations occurred at 14 – 13 ka, 11 ka, 5 – 6 ka, 1 – 2 ka, and 0.2 ka. We suggest that 20<sup>th</sup> century glacial recession is occurring faster than at any time documented during the Holocene. </p>


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