The Geomorphology and Glacial History of the Central Area of Nahanni National Park: A Preliminary View

Abstract

<p>A preliminary study of the geomorphology and glacial history of the central portion of Nahanni National Park in the District of Mackenzie, N.W.T. was undertaken. To provide a context for the work a comprehensive review of the literature dealing with the glacial history of the entire Yukon-Western District of Mackenzie Region is attempted and the various chronologies for different areas within the region are correlated. The subject area itself, 2,600 sq. km. in size and constituting the central portion of the Park was studied through the use of aerial photographs supplemented by limited field work. A geomorphic map of the glacial, glaciofluvial, gluvial and periglacial features of the Central Nahanni has been prepared at a scale of 1:125,000. Of particular note is the presence of extensive deposits of lacustrine silts.</p> <p>Detailed study of the extent, stratigraphy and lithology of the lacustrine deposits indicates that on two separate occasions in the past a large proglacial lake occupied the lower Flat and central South Nahanni river valleys to a minimum elevation of 610 meters. The younger lake has been named Lake Nahanni and the older lake, of considerably greater age, is herein named Lake Caribou. Evidence from within the study area in conjunction with results obtained in other areas within the region is utilized to present a glacial chronology for the Central Nahanni. In this chronology it is suggested that Lake Nahanni is early Wisconsin or older in age. Lake Caribou is considered to be pre-Wisconsin in age.</p>