We know that the processes of erosion and weathering will continue, that alluvial fans and talus cones will grow larger, and gorges will be eroded deeper, and as a result the mountains will be cut down to lower elevations. But, as we have seen, this event will require much time. If the present climate continues for a few more years our remaining glaciers will disappear, but there is nothing in geologic history which says they won’t return again, possibly even to the size of their heyday in the Pleistocene. And if history repeats itself, and all past geologic history has been a repetition, then the mountains will eventually be worn down to an uneventful plain and the sea will invade the land again. But certain breeds of man are the only despoilers of mountains that we need fear, so if the good citizens of our land keep the human invader and his dams and earth-moving equipment out of our national parks these grand mountains will endure for many thousands, yes, even millions of years. Footnotes [1]Dr. Dyson worked as a ranger-naturalist in Glacier National Park for eight summers starting in 1935. [2]Argillite is the term used by geologists for a rock, originally a shale, which has been recrystallized or made harder by greater pressure. In external appearance it looks like shale. [3]A dike is like a sill in all respects except that it cuts across adjacent layers instead of paralleling them. [4]For a complete discussion of glaciers and their effects see Special Bulletin No. 2 (Glaciers and Glaciation in Glacier National Park) of the Glacier Natural History Association. PRINTED IN U. S. A. BY GLACIER NATURAL HISTORY ASSOCIATION IN COOPERATION WITH NATIONAL PARK SERVICE DEPARTMENT OF INTERIOR 1953 O’NEIL PRINTERS—KALISPELL, MONTANA Principal Aims of the GLACIER NATURAL HISTORY ASSOCIATION, Inc. Glacier National Park West Glacier, Montana Organized for the purpose of cooperating with the National Park Service by assisting the Naturalist Department of Glacier National Park in the development of a broad public understanding of the geology, plant and animal life, history, Indians and related subjects bearing on the park region. It aids in the development of the Glacier National Park museum library, museums and wayside exhibits; offers books on natural history pertaining to this area for sale to the public; assists in the acquisition of non-federally owned lands within the park in behalf of the United States government; and cooperates with government projects in the completion and development of Glacier National Park as needed.