SELKIRK MOUNTAINS  , a range in the S.E. of British Columbia, Canada, extending N. for about 200 M. from the American frontier with a breadth of about 8o m. and bounded E., W. and N. by the Columbia river . Though often spoken of as part of the Rocky Mountain system, they are really distinct, and belong to an older geological epoch; consisting mainly of crystalline or highly metamorphosed rocks, granites, gneiss, schists; their outline too is rounder and less serrated than that of the Rockies . On the S.E. is the Purcell range, with the main chain of the Rockies still farther E., and on the W. the Gold range, prolonged northward as the Cariboo Mountains . They do not rise much above to,000 ft., the highest peaks being Sir Donald (named after Lord Strathcona), 10,645 ft.; Macdonald (named after Sir John Macdonald), 9440 ft.; and Mount Tupper (after Sir Charles Tupper), 9030 ft . The scenery is wild and magnificent; below the snow-line, especially on the western side, the slopes are densely wooded, and enormous glaciers fill the upper valleys; of these the most celebrated is that of the Illecillewaet, near Glacier House, on the Canadian Pacific railway . The Selkirks are crossed by the railway at Rogers Pass, discovered in 1883 . The engineering difficulties overcome are greater than at any other portion of the line, and the grades are in places very steep . A magnificent series of caverns, called the Nakimu Caves, occur in the Glacier Park Reserve not far from Glacier on the Canadian Pacific railway . These caves are formed by the Cougar Creek, and were first comprehensively surveyed in 1905-1906 (see the Canadian Surveyor-General's Report for that year) .