A study of the effect of soil forming processes on serpentine rock at Clangula Lake, Manitoba

Abstract

Extensive areas in the vicinity of Clangula Lake are covered by a reddish brown to greyish brown soil. This soil overlies a narrow zone of serpentinized peridotite which extends eastward from Clangula Lake for several miles. The most prominent exposure occurs at the serpentine quarries about half a mile east of the lake. It has been suggested that this soil is a residual weathering product of the underlying serpentine rock. If this assumption is correct, certain controversies arise regarding the origin of the soil and the nature of the weathering. The lack of a glacial drift mantle over much of the area would suggest either post-glacial denudation of the drift, followed by considerable chemical weathering of the serpentine rock, or pre-glacial weathering which was subsequently modified by glacial and post-glacial phenomena. The problem, therefore, is resolved into 1) a study of the weathering products to verify their residual character, and to determine the processes by which they were formed, and 2) a study of the Pleistocene geology of the area to determine the local effects of glaciation. The field work on the problem was done in September, 1948, while the writer was employed by the Manitoba Mines Branch as a student assistant on a geological survey party in the English Brook area. Samples of soil profiles were taken from surface to "unweathered" bedrock from the quarries east of Clangula Lake. The area surrounding the quarries was mapped by pace and compass with the object of preparing a large-scale topographic and geologic map...