Ecological Land Classification of Mount Revelstoke and Glacie r ...

CHAPTER I - PHYSICAL ENVIRONMEN TLOCATION, PHYSIOGRAPHY AND DRAINAGE SYSTEM SD .T. Allan, B.D .Walker and W .S . TaylorLOCATIONMount Revelstoke National Park (MRNP) and Glacier National Park (GNP) are in the Columbi aMountains (Holland 1964, Bostock 1970) of southeastern British Columbia (Fig . 1) . MRNP extend snorth to south approximately 20 km between 51°00' and 51°12' N and east to west about 22 km between11752' and 118°13' W . MRNP occupies 260 km 2 with the city of Revelstoke near the south -west boundary .GNP extends north to south for approximately 50 km between 51°02' and 51°29' N and east to wes tfor approximately 50 km between 11712' and 11755' W . It covers 1349 km 2 and is centered on Rog -ers Pass, British Columbia . The Trans-Canada Highway and Canadian Pacific Railway both transec tGNP extending from the northeastern corner along the Beaver River to the western boundary alon gthe Illecillewaet River .PHYSIOGRAPHYMRNP and GNP occur in the Columbia Mountains of the Southern Plateau and Mountain Are awhich is in the Interior System of the Canadian Cordillera (Holland 1964, Bostock 1970) .Physiography and landform in the Canadian Cordillera Region are governed by geomorphic process ,bedrock character, and orogenic or structural history (Holland 1964) . MRNP and GNP are underlainpredominantly by folded and faulted metasedimentary rocks uplifted by orogenic deformation durin gthe Tertiary (Holland 1964) . Erosion, mainly fluvial and glacial, has operated since then . The generaltopography is controlled by differences in resistance to erosion . Valleys reflect softer rocks whilepeaks and ridges are underlain by more resistant beds . Bedrock here trends northwesterly which controlsthe direction of the ranges and has imposed a trellis-like pattern on the drainage systems (Holland1964) .MRNP and GNP contain portions of the Selkirk Mountains and the northwestern flank of the Purcel lMountains, two of four major Columbia Mountain subdivisions (Holland 1964, Baird 1965, Bostoc k1970) . The Selkirks are composed mostly of three bedrock groups that control general topography i nMRNP and GNP : Hamill Group, Lardeau Group, and Shuswap Metamorphic Complex . With theaddition of the Horsethief Creek Group, which dominates the northwestern Purcells, MRNP an dGNP encompass four physiographic units that reflect bedrock geology .Easternmost GNP is in the Purcell Mountains and is separated from the more rugged Selkirks by th eBeaver River valley also called the Purcell Trench (Wheeler 1963) . Recessive, slate and schist bedroc kin this area of the Purcells controls the general topography which is the most rounded and subdued i nthe two parks (Plate 1) . High elevation topography, with low to moderate internal relief, includesboth broad and narrow, rounded, ridge tops and poorly defined cirques and valley shoulders. Most ofthese landscapes show evidence of glaciation but present glaciers are few and very small . Mountainpeaks are also poorly defined being little more than elevated parts of the interconnecting ridges . Mostare rounded or elongated and