Phase Of Glacier Research Articles

Last glacial geomorphologic records in Mt Chelmos, North Peloponnesus, Greece

This study deals with the analysis of the glacial processes that have affected the relief of Mt Chelmos in northern Peloponnesus, Greece during middle and Late Pleistocene. The goal was to compile a combined geomorphological-geological map of the study area which would enable the chronological stratification of the glacial landforms cropping up on Mt. Chelmos. Chronological stratification was further aided by optically stimulated luminescence (OSL) dating. The map served as the basis upon which the reconstruction and discussion on the phases of the Middle-Late Quaternary paleoclimatic history of Mt. Chelmos have been made. A sophisticated semiautomated method was first used to analyze the Digital Elevation Model (DEM), combined with Aster, Quickbird and ALOS imagery in order to identify glacial and periglacial, as well as karstic features. Then, these features along with other nonrecognizable features from the remote-sensing images were documented in the field. In this way, several glacial landforms were identified, such as moraines and cirques, indicating extended glaciation phases during the middle and Late Pleistocene. Additionally, a ground moraine located at an altitude of 1900-2050 m, within the Spanolakos glacial valley, was dated using the OSL-dating method. The resulting ages indicate a phase of glacier advance/stabilization during MIS-5b (89-86 ka), which is in consistence with pollenrecord evidence from Greece and the Mediterranean.

Deglaciation of the eastern flank of the north patagonian icefield and associated continental‐scale lake diversions

ABSTRACT. We examine the deglaciation of the eastern flank of the North Patagonian Icefield between latitudes 46° and 48°S in an attempt to link the chronology of the Last Glacial Maximum moraines and those close to present‐day outlet glaciers. The main features of the area are three shorelines created by ice‐dammed lakes that drained eastwards to the Atlantic. On the basis of 16 14C and exposure age dates we conclude that there was rapid glacier retreat at 15–16 ka (calendar ages) that saw glaciers retreat 90–125 km to within 20 km of their present margins. There followed a phase of glacier and lake stability at 13.6–12.8 ka. The final stage of deglaciation occurred at c. 12.8 ka, a time when the lake suddenly drained, discharging nearly 2000 km3 to the Pacific Ocean. This latter event marks the final separation of the North and South Patagonian Icefields. The timing of the onset of deglaciation and its stepped nature are similar to elsewhere in Patagonia and the northern hemisphere. However, the phase of lake stability, coinciding with the Antarctic Cold Reversal and ending during the Younger Dryas interval, mirrors climatic trends as recorded in Antarctic ice cores. The implication is that late‐glacial changes in southern Patagonia were under the influence of the Antarctic realm and out of phase with those of the northern hemisphere.

Applications of Landsat Imagery in the Great Plains

Landsat MSS digital data and imagery are utilized to demonstrate applications in geology and hydrology for two regions of the Great Plains-Devils Lake, North Dakota and the Flint Hills, Kansas. Devils Lake occupies several, internally connected glacial basins that have no outlet at present. Consequently lake surface elevation, water volume, salinity, and biomass fluctuate significantly with climatic changes. During the period 1973-1988, the lake rose 3 m; Landsat images document an increase in surface area of more than 50%. Glacial landforms include large ice-shoved hills, ice-scooped depressions, spillway channels, and tunnel valleys. These features are interpreted as the results of glacier thrusting and melt-water erosion in connection with two converging ice lobes during a late phase of glacier advance. In the Flint Hills of east-central Kansas, stream valleys follow distinct lineaments oriented NW-SE, NNE-SSW, and NE-SW. These lineaments correspond to crustal fractures (joints and buried faults). Based on Landsat imagery, another significant lineament trend at NNW-SSE (about 350'-170') has been identified. This trend is named the Verdigris lineament, and it represents an important fracture system in east-central Kansas. The Verdigris lineament relates to bedrock joint trends in the Flint Hills region.