CGRG Bibliography of Canadian Geomorphology
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Author : Campbell, J.E.; Fenton, M.M.; and Pawlowicz, J.G.
Date : 2001.
Title : Surficial Geology of the Pelican Area (NTS 83P), Alberta. 1:250,000 scale
Publication : Alberta Energy and Utilities Board/Alberta Geological Survey, Map
Issue : 251.
Page(s) :
Abstract
The Peerless Lake area has been subjected to several minor Quaternary studies by the Alberta Geological Survey (AGS) since 1992. As part of a multi-year program initiative, AGS completed a surficial mapping program in 2001-2002. The impetus for this recent study was the discovery of 36 kimberlite pipes in the Buffalo Head Hills - Loon River Lowlands. The physiography of the map area is dominated by the Buffalo Head Hills to the west and the Peerless Highlands to the east, which are separated by the Loon River Lowlands. The highlands are characterized by extensive areas of stagnant ice terrain that is dissected by multiple meltwater channels. In contrast, organic terrain, interspersed with glaciolacustrine and glaciofluvial sediments, occupy the lowlands. Drift thickness is variable, from <2 m in the Buffalo Head Hills to >200 m in the Loon River Lowlands. In a few places, outcrops of kimberlite (e.g., K5 and K6) in the Buffalo Head Hills form small, prominent knobs that protrude above the surrounding stagnant ice terrain. On the top of the Buffalo Head Hills, areas of thin (<2 m) till were found overlying sandstone and shale bedrock. The occurrence of these outcrops was previously unknown; palynological analysis shows the bedrock is an outlier of Wapiti Formation sandstone of Late Campanian age. This is considerably younger than the previously mapped Smoky Group. Additionally, a thin veneer of preglacial (Tertiary?) quartzite gravel discontinuously overlies the bedrock in these areas of shallow drift cover. An extensive esker and ice-contact meltwater complex was observed in the southwest corner of the map area. Other notable glaciofluvial features include the Trout River meltwater channel, which occurs near the western edge of the Peerless Highlands, and a kame complex adjacent to Gods Lake. These are excellent sources of aggregate in a region that has limited aggregate resources. Special attention was paid to the various ice flow indicators in the region. Ice flow history and flow directions in northern Alberta are generally interpreted exclusively from streamlined surface landforms. However, it must be stressed that these landforms only represent the final chapter of a long story of ice movement during the Late Wisconsin. The sparse occurrences of outcrop and the complete lack of preserved striae on the soft clastic bedrock prevent any preliminary interpretations on early and regional glacial flow patterns. Pebble fabric measurements on surface tills are generally parallel to the regional landforms. Widespread deposition of englacial and supraglacial debris, in the form of thick, hummocky, stagnant-ice terrain, also masks regional ice flow indicators. Regardless of these difficulties, an interpretation of ice flow history and directions in the Peerless Lake area has been determined from streamlined landforms, glacial thrust ridges and pebble fabric measurements. Early glacial flow was likely dictated by topography, but as ice sheet thickness increased during the glacial maximum (ca. 22,000 to 18,000 years before present or B.P.), ice was unimpeded by local topography and generally flowed to the southwest. Flutings scoured into the bedrock on the Buffalo Head Hills, and a well-preserved crag and tail landform at the K5 kimberlite outcrop, are parallel to this regional ice flow interpre-tation. In contrast, flutings and linear landforms on the northeastern flank of the Peerless Highlands indicate a south-southeasterly ice flow. This suggests that late-stage ice was deflected due to topographic control of the thinning ice sheet. A rare boulder pavement was also discovered at the Red Earth airport. Striae, measured from the planed tops of the boulders, indicate the surface till in the Loon River Lowlands was deposited by ice flowing southward (188°). Then, during early deglaciation (ca. 13,000 to 11,000 years B.P.), several areas were submerged by glacial lakes as the northward-retreating ice blocked meltwater drainage. Finally, beautifully preserved flutings in the southeast suggest that southwestwardly flowing ice re-advanced into a large glaciolacustrine lake that occupied the Wabasca River lowland to the northeast
Bibliography of Canadian Geomorphology