Glacial geomorphology and chronology in the Selamiut range / Nachvak fiord area, Torngat Mountains, Labrador

Evans, D. J. A. (1984) Glacial geomorphology and chronology in the Selamiut range / Nachvak fiord area, Torngat Mountains, Labrador. Masters thesis, Memorial University of Newfoundland.

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Abstract

The summits of the Selamiut Range are the highest in the Torngat Mountains of northern Labrador and contain some of the only permanent ice bodies of the eastern Canadian mainland. As they may have constituted a physical barrier to ice moving eastward from the Ungava ice-dispersal centre, their glacial history is elaborate in a regional context. Consequently a complex interaction of local and regional ice masses is manifest in the morphochronological record dating from the Late Quaternary through the Holocene. -- Physiographically the Selamiut Range is a plateau, dominated by deep cirques and cirque outlet valleys with precipitous bounding rock walls. Colluvial processes are extremely active and consequently many surficial units have been extensively remodelled in dynamic landscape systems. -- The northern half of the field area contains a wealth of glacial and periglacial landform assemblages and former local and regional ice activity has been determined from the cross-cutting relationships of certain morainic features. -- Within the McCornick River Valley a sequence of shorelines documents the depths and extent of ice-dammed lakes during glaciation. A further 33 metre marine limit demarcates former sea level during the final glaciation of the area. -- Three glaciations or stillstands are suggested for the field area after consideration of the landform evidence and are named the Ivitak, Nachvak and Superguksoak Glaciations. -- The adoption of a 1.5 cm ka ⁻¹ soil development rate dates the three glaciations or stillstands for the Selamiut/Nachvak area; the Ivitak Glaciation at >>40 ka; the Nachvak Glaciation at c.23 ka; and the Superguksoak I Glaciation at 10-12 ka. B.P. Two further Neoglacial events were restricted to the cirque basins and are correlated locally by a combination of pedology, lichenometry and morphologic superimposition. -- A number of chronocorrelative inferences are made for northern Labrador based upon the existing empirical data. Glacial styles appear to differ quite considerably from fiord to fiord along the coastal section of the Torngat Mountains. The solution of discrepancies within the general northern Labrador chronology resides in the successful construction of an absolute dating framework for the marine limits of the region. Relative chronologies may then attain a significant applicability.

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