Multiple Glaciations Research Articles

A single, late Wisconsin, Laurentide glaciation, Edmonton area and southwestern Alberta

The absence of igneous and metamorphic clasts of Canadian Shield origin in the Saskatchewan gravels and sands (preglacial) valley fills in seven active gravel pits studied over a 5 yr period, coupled with 29 radiocarbon dates (21,300-42,910 yr B.P.), suggest that Laurentide glaciation prior to the late Wisconsin did not reach the Edmonton area. On the basis of Edmonton9s elevation (∼670 m above sea level [asl]), compared to higher regional elevations to the south (Calgary, ∼1060 m asl), and maps of the retreat pattern of late Wisconsin Laurentide ice (which we equate approximately with advance pattern), it is likely that large areas of higher elevation in Alberta, south and west of Edmonton, only underwent the late Wisconsin event, not multiple glaciations.

Studies of Cainozoic environmental change in Tasmania and coastal East Antarctica: a review

SUMMARY Observational studies on Cainozoic environmental changes in both Tasmania and East Antarctica have led to important modifications in the accepted interpretation of the history of glaciation for each area. Many contributors have played an important role in the processes of investigation leading to the present state of knowledge. A crucial role has been played by the integration of the methods of glacial geomorphology, stratigraphy, sedimentology and dating methods. From studies based on combinations of these approaches, a model of multiple glaciations has been developed to explain observed features in Tasmania. This model is complemented by studies of vegetation history, largely through pollen analysis. A less complete picture of the history of ice‐sheet fluctuations in East Antarctica is beginning to emerge from similar applications of cross‐disciplinary studies.

Compression characteristics and index properties of tills and intertill clays in southern Saskatchewan, Canada

Compression characteristics and index properties of unweathered tills and clays from repeated glaciations follow a predictable pattern at 10 sites along a 1300-km transect across southern Saskatchewan. A surface ablation melt-out till of the Battleford Formation is normally consolidated, a basal melt-out till of the Battleford Formation is moderately overconsolidated (σp′ = 400–750 kPa), and the older (pre-Battleford) tills and intertill clays are heavily overconsolidated (1800 ± 200 kPa). Variation in lithology, as indicated by Atterberg limits, is small within formations which reflected in the compression index. The older tills of the Sutherland Group are highly plastic compared with the younger tills of the Saskatoon Group. The in situ dry density of the youngest (Battleford) till is slightly above 100% maximum Proctor density. The in situ dry density of the older (pre-Battleford) tills is at or above the 100% maximum modified Proctor density. At these high densities the in situ degree of saturation is 94.5 ± 4.8%; as compared with Proctor optimums at 80.3 ± 3.8%. It is not practical to increase bearing capacity of the tills by compaction. Disturbance by compaction equipment could cause a decrease in density. Key words : preconsolidation, tills, intertill clays, Proctor density, multiple glaciations.

Late Wisconsinan stratigraphy in the lower Sandy River valley, New Sharon, Maine

Research Article| October 01, 1992 Late Wisconsinan stratigraphy in the lower Sandy River valley, New Sharon, Maine THOMAS KIRK WEDDLE THOMAS KIRK WEDDLE 1Maine Geological Survey, State House Station No. 22, Augusta, Maine 04333 Search for other works by this author on: GSW Google Scholar Author and Article Information THOMAS KIRK WEDDLE 1Maine Geological Survey, State House Station No. 22, Augusta, Maine 04333 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1992) 104 (10): 1350–1363. https://doi.org/10.1130/0016-7606(1992)104<1350:LWSITL>2.3.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation THOMAS KIRK WEDDLE; Late Wisconsinan stratigraphy in the lower Sandy River valley, New Sharon, Maine. GSA Bulletin 1992;; 104 (10): 1350–1363. doi: https://doi.org/10.1130/0016-7606(1992)104<1350:LWSITL>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Quaternary glacigenic deposits exposed along the Sandy River valley in New Sharon, Maine, are associated with ice-proximal deposition in a northeast-trending stream valley. Fine-grained sediments represent distal deposits by turbidite deposition, turbid sediment plumes, and associated ice-rafted debris in a proglacial lake. Coarse-grained deposits and stratified diamicton are ice-proximal sediments deposited by gravity-flow processes, subaqueous sediment discharge, and fluvial deposition. Massive diamicton was deposited by subaqueous sediment discharge or by subglacial processes.In contrast to previous depositional models that call for multiple glaciations to reflect the various facies, the glacigenic sediments at New Sharon were deposited entirely during a single glacial cycle, the late Wisconsinan. Glacitectonic and petrofabric data reflect an upsection shift in deformation from a northeast to a northwest source, attributed to late Wisconsinan sublobes in the Sandy River and Kennebec River valleys. Ice in the Kennebec River valley dammed drainage in the northeast-oriented lower Sandy River valley, creating a proglacial lake into which both sublobes deposited and deformed proglacial sediments during the early late Wisconsinan. Mainphase Laurentide ice eventually merged with and overwhelmed the sublobes. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Multiple Glaciation in Scandinavia—Seen in Gross Morphology or Not?

Multiple glaciations are probable in Scandinavia for various reasons, but all glaciations do not need to have covered the whole area. The glacial gross forms are tested, first in general. The great...

Multiple glaciations and sea level changes, northern Ellesmere Island, high arctic Canada

Along the northern coasts of Ellesmere Island, at least two glaciations are recognized on the basis of morphostratigraphy. The early Holocene ice limit lay only 5 to 60 km beyond present glaciers due to constraints imposed by aridity and calving. This limited ice advance likely extended beyond any Wisconsinan glacial limit. Marine limits established during, retreat from the last glacial maximum reach 148 m a.s.l. In contrast, earlier, more extensive glaciations inundated the coastlines and are associated with former relative sea levels now reaching 286 m a.s.l. Correlation of these pre‐Wisconsinan glaciations is based upon amino acid ratios. However, this approach is severely limited by slow rates of racemization, a lack of in situ samples, and complex thermal histories owing to multiple transgressions. Models favoring extensive regional glaciation of northern Ellesmere Island and Greenland must include a glacioclimatic scenario recognizing the constraint that aridity places on glaciation. We suggest that the large ice volume associated with the oldest recognized glaciation relates to a period of reduced sea‐ice cover, possibly &gt;400,000 BP, and may correlate with an interglacial stage of the marine oxygen isotope record.

Multiple glaciations and marine transgressions, western Kennedy Channel, Northwest Territories, Canada

Along a 70 km section of western Kennedy Channel three prominent weathering zones are identified and serve to differentiate major events in the Quaternary landscape. The oldest zone (Zone 111b) is characterized by a deeply weathered, erratic‐free terrain which extends from the mountain summits down to ca. 470 m above sea level. This zone shows no evidence of former glacierization. Zone 111a extends from ca. 470 to 370m above sea level and is characterized by sparse granite, gneiss and quartzite erratics amongst weathered bedrock and extensive, oxidized colluvium. The Precambrian provenance and uppermost profile of these erratics reflect the maximum advance of the northwest Greenland Ice Sheet onto northeastern Ellesmere Island. These uppermost erratics along western Kennedy Channel decrease in elevation southward and suggest that the former Greenland ice was thickest in the direction of the major outlet of Petermann Fiord. No evidence of a former ice ridge in Nares Strait was observed. Zone II is marked by the moraines of the outermost Ellesmere Island ice advance which form a prominent morpho‐stratigraphic boundary where they cross‐cut the zone of Greenland erratics at ca. 250–350 m above sea level. These moraines show advanced surface weathering and ice recession from them is associated with a pre‐Holocene shoreline at 162 m above sea level. Late Wisconsin/Würm glacial deposits, equivalent to Zone I, were not observed in the lower valleys bordering Kennedy Channel. The outermost Ellesmere Island ice advance (Zone II) is radiometrically bracketed by 14C dates on in situ shells from subtill and supratill marine units which are 40,350±750 and&gt;39,000 B.P., respectively. Amino acid age estimates on the same shell samples and others from similar stratigraphic positions all suggest ages of &gt;35,000 B.P. Stratigraphically and chronologically this ice advance is correlated with the outermost Ellesmere Island ice advance 20–40 km to the north which formed small ice shelves when the relative sea level was ca. 175 m above sea level. The Holocene marine transgression along western Kennedy Channel occurred in an ice‐free corridor maintained between the separated margins of the northwest Greenland and northeast Ellesmere Island ice sheets during the last glaciation. Initial emergence may have begun ca. 12,300 B.P., however, sea level had dropped only 15 m by ca. 8000 B.P. after which glacio‐isostatic unloading of the corridor was rapid. The implications of these data are discussed in the context of existing models on high latitude glaciation and paleoclimatic change

Glacial Geology of the Frying Pan River Drainage, Colorado

On the west flank of the Sawatch Range, Colorado, evidence is found for six distinct glacial advances One glaciation is pre-Wisconsin, four are Wisconsin, and one post-Wisconsin in age. In addition to end and lateral moraines of each advance, terrace remnants of six valley trains were identified and studied for a distance of 25 miles along Frying Pan River and its major tributaries. Elevations above stream level of these outwash terraces are 400-450, 90-120, 50-40, 20-30, 12-17, and 6-8 feet. Five of the tributary valleys contained large ice streams which did not join the trunk Frying Pan glacier during the Wisconsin stage. Extensive review and testing of the numerous criteria used to distinguish deposits of multiple glaciations show that nine of these criteria can conveniently be expressed in parameters indicative of relative age. Estimates based on these criteria, coupled with a recent radiocarbon dating of late Mankato till in the Midwest, yield the following approximate ages for deposits of the six glaciations in Frying Pan Valley: 230,000, 63,000, 46,000, 17,000, 11,500, and 5,750 years. The accuracy and reliability of the procedure used cannot be evaluated without further absolute Carbon 14 age determinations.