Logan, Mount, elev 5959 m, is Canada's highest mountain, named after Sir William E. Logan by Prof I.C. Russell, who first saw it during an attempted ascent of Mt St Elias in 1890. Situated in the Yukon T's St Elias Mts, it is one of the world's most massive mountain blocks, rising abruptly 4150 m above the flat Seward Glacier on the south side. The mountain is largely composed of granodiorite, a granitic rock of intrusive origin. Multiple summits rise above a NW-SE elongated snow and ice plateau varying in elevation between 4500 m and 5400 m and extending over a distance of 19 km. Three of the summits exceed 5890 m in elevation.
In 1925, a joint Canadian-US expedition, led by A.H. MacCarthy, made the first ascents of the Weak Peak (5915 m) and the High Peak (5950 m, then believed to be 6050 m high;