CGRG Bibliography of Canadian Geomorphology
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Author : Endres, A.L.; Martini, I.P.; and Sadura, S.
Date : 2004.
Title : GPR stratigraphy of an end moraine and outwash complex: Paris moraine near Arkell, Ontario.
Publication : 49th Annual Meeting of the Geological Association and the Mineralogical Association of Canada. May 12-14, 2004. Brock University, St. Catharines, Ontario.
Issue :
Page(s) :
Abstract
One of the best examples of an Upper Pleistocene end moraine system in southern Ontario is the Paris Moraine formed by the Lake Ontario lobe of the Laurentide Ice Sheet. To investigate the stratigraphy and depositional environments in this system, an extensive program of ground penetrating radar (GPR) profiling has been undertaken over the moraine and adjacent outwash complex at and around the Arkell Research Station of the University of Guelph. All of profile lines were acquired using 50 MHz antennae to maximize the depth of investigation; selected lines were also acquired with 100 and 200 MHz antennae to obtain finer resolution images of stratigraphic structures. Dip profiles on the frontal slope of the moraine ridge are characterized by relatively continuous, sub-parallel reflections, defining a series of vertically stacked, wedge-shaped packages that pinch out in the downdip direction. The internal configuration of these packages is discontinuous, locally hummocky reflections. Strike lines on the frontal slope show that the lateral continuity of these packages tends to decrease as one proceeds up the moraine toward its crest. These wedge packages are interpreted to be aprons (fans) of debris-flow diamicton and waterlaid sediments; their internal configuration indicate wide cuts-and-fills and/or noses of gravity flow emplaced bodies The GPR reflection pattern of the hill crest and back-slope portions of the moraine are significantly different and suggest the possibility of faulting associated to ice push. Proximal outwash profiles running parallel to the moraine trend show sequences of strong, undulose, reflectors, discontinuous on the scale of 10-20 m; these reflector patterns suggest multiple, nested channels. At least three vertical phases of channeling can be seen on the profiles. A portion of the proximal outwash sequence is overlain by the moraine frontal wedge units. The lower limit of the outwash deposit on the profiles is commonly a strong, continuous basal reflector. The good depth of signal penetration in both the moraine and outwash deposits indicate that these are composed of sandy diamicton and washed sand and gravel, respectively. The thickness of the outwash deposit generally decrease away from the moraine; however, there is significant local variation partly due to the underlying topography characterized by the local presence of buried to partially buried drumlins.
Bibliography of Canadian Geomorphology