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Elm landslide of the Swiss Alps or the rockslide of a few years ago which wiped out a goodly portion of the town of Frank, Alberta.

In years past extensive areas in the vicinity of the Lizard's Head have been subject to monstrous rock and land slides, in some instances the entire faces of large mountains having been demolished. The last landslide occurring in the San Juan Mountains was also fortunately in an uninhabited area. It occurred in 1886 in the Cimarron Creek Valley, covering about three square miles and every living creature in the area must unquestionably have been killed outright. The scene of the slide was visited within a few days by Whitman Cross, a geologist of the United States Geological Survey accompanied by a photographer. The area had been well timbered but the trees were all overturned, broken down, or standing at various angles, presenting a weird picture. slopes were exposed and fissures left gaping. Yet this slide, according to Doctor Cross was largely surfical, a soil slip rather than a rock or landslide, and possibly not to be compared with the rockslide at Lizard's Head.

Bare

It is the younger mountain systems, geologically speaking, which are most subject to these rock avalanches. The Himalayas, which are comparatively recent examples of mountain building, have constant slides which would constitute great great catastrophes were their slopes and valleys populated. Sir William Conway describes an instance of rock tumbling which caused the formation of Gohna Lake in the central Himalayas where the spur of a large mountain mass pitched bodily into the valley below. The front of the mountain had been undermined by springs and in the twinkling of

tain slid down and shot across the valley, damming its river with a lofty wall. Masses of rock were hurled a mile away. It is estimated that this slide carried with it eight hundred million tons of rock and debris. Plenty of Himalaya rockslides quite as extensive as this, have been recorded in the last half century, while among the remote and uninhabited regions of the great ranges rockslides are of constant occurrence.

The formations of the Colorado landslide-area point to many such slides as these in times past. Fortunately this wholesale catastrophe era is ended for the mountains of this country, though the recent destruction of Lizard's Head and the Cimarron slide show that all danger is not past, while slides in the Alps and

in Alberta indicate man's mining operations may precipitate such disasters.

The landslide areas of Colorado show that in the earlier days, recent geologically, but probably scores of centuries before the coming of man, there must have been terrific times among our mountains. To the geologist the evidence is plain that there have been thousands of slides, and some of them of enormous magnitude. Possibly the great sabretoothed tiger which ranged the valleys below, and the giant dinosaur upon which he preyed, along with other prehistoric animals heard the terrifying roar of the descending rock masses; but if so, man knows it not, for the exact age of the older and greater disturbances can be only guessed.