Abstract
A PAPER of more than usual interest was read at Monday's meeting of the Royal Geographical Society, by the Rev. W. Spotswood Green, on his explorations in the glacier regions of the Selkirk Range, British Columbia, in the summer of 1888. This range is generally included in the Rocky Mountains, although, as Mr. Green showed, it is in many respects distinct from them. After crossing the Rockies by the Canadian Pacific Railway, and plunging into the valley of the Columbia River, the Selkirk Range lies before the traveller. It has been but little explored, and some of its glaciers were probably visited for the first time by Mr. Green. The Selkirk Range is entirely bounded by the great bend of the Columbia and its tributary, the Kootenie, and the drainage of all its glaciers finds its way into the Columbia in some part or other of its course. Under many difficulties, owing to the densely forest clad nature of the ground, the want of guides and porters, the necessity of opening up new routes, and other causes, Mr. Green visited some of the higher parts of the range, and explored, and in some cases named, its previously unvisited glaciers. After crossing the Rockies proper, curiously ridged prairie hills have to be parsed, and all the ranges between these and the Columbia have a smooth rounded outline, forming a strong contrast to the ranges on the other side of the watershed. These latter form a complexity of glacier-clad ranges, many peaks rising quite as high as those on the watershed. Among the higher ranges an immense number of small glaciers lie in the hollows, and two extensive snow-fields are to be found within the limits of Mr. Green's map. One of these, being the source of the best-known glacier in the whole region, on account of its being so clearly visible from the railway, Mr. Green has called the great Illecellewaet firn, after the river of which it is the true source. This ice-field, probably 500 feet thick, to the southward extends down into a valley as the Geikie Glacier, and to the eastward, having been joined by ice-streams coming from the Dawson Range, it pours into Beaver Creek Valley as the Deville Glacier. All these glaciers show evidence of shrinking. An immense moraine exists in the valley below the Illecellewaet Glacier. Some of the blocks of quamite in the moraine are of huge dimensions, one being 50 feet long,. 24 feet thick, and 33 feet high. Mr. Green set up some poles at a little distance from the end of the glacier, and found that after thirteen days the ice had melted a vertical foot over its whole surface, and the centre of the glacier had moved 20 feet. The Geikie Glacier, about 4 miles long and 1000 yards wide, is a much more interesting ice-stream. Sheltered from the sun's rays by high cliffs, it flows along a level valley, so that one can walk across its lower portion in various directions without trouble. As it descends from the firn, it is much broken; then its surface becomes level, but with numerous transverse crevasses. Flowing round abend, longitudinal fissures are set up, crossing the others, and forming such a multitude of séracs that the surface presents an appearance more like some basaltic formation with the columns pulled asunder than anything else I can think of. This beautiful structure gives place to the frozen waves of a mer de glace, and the glacier terminates in longitudinal and slightly radiating depressions and crevasses. The level of perpetual snow in these mountains may be put down at 7000 feet, and. the upper limit of the forest at 6000 feet. Red snow, caused by the presence of Protococcus nivalis, is of frequent occurrence. Like most of the rest of British Columbia, the Selkirks are covered with forests, all the trees attaining huge dimensions. These forests are being devastated by fires, often caused by sparks from the engines on the new railway. Beneath the living trees, thousands of prostrate trunks lie piled in every conceivable position, and in every stage of decay. Exploration and mountaineering under such circumstances are attended with enormous difficulties. Above the forest region, the slopes of the mountains are as profusely covered with flowers as the Alp region of the Swiss mountains; the most conspicuous plant being the Castilleia miniata. The heaps of boulders above the forest region form a refuge for a great variety of small animals. With regard to the geology of the Selkirks, earlier than the Glacial formation, no rocks later than the Palæozoic seem to be met with in the central range. In the higher ranges, greenish quartzites and micaceous schists are the commonest rocks. The summit of Mount Bonney and the southern and south-western arêtes of Mount Sir Donald consist of a beautiful white, smooth quartzite, speckled in the former case with deep brown spots, “probably iron or manganese oxides.” Associated with these harder rocks are a number of remarkable silky-looking schists (phylites of Prof. Bonney), the result of great squeezing in the movements which upheaved the ranges. Roughly speaking, then, the configuration of this district, with its complexity of valleys, is due to the disintegration and denudation of the softer schists and the permanence of the harder quartzites in mountain-ridges. With regard to age, the rocks range from true Archaean to late Palæozoic, possibly a little later. The presence of very old schists and gneisses would seem, then, to show that though the range called the Rockies, on the Canadian Pacific Railway route, is the water-parting, the Selkirks are geologically the true continuation of the Rocky Mountains of Montana, and the backbone of the continent.
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Geographical Notes . Nature 39, 379–380 (1889). https://doi.org/10.1038/039379b0
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DOI: https://doi.org/10.1038/039379b0