It is well known that the Sierra Nevada and Cascade ranges intercept, moisture from the Pacific, causing it to be precipitated on their western slopes with resulting arid or semi‐arid conditions east of them. In a less degree the Rocky Mountains effect a similar result, particularly north of the latitude of Yellowstone Park. Precipitation on their western sides or westernmost ranges, such as the Clearwater Mountains, Cœr d'Alene, Cabinet, and Purcell ranges is much greater than on the ranges farther east or the plains beyond. It follows that if the intercepting ranges were removed or even lowered considerably, the interior plateaus and the great plains in northern United States and Canada would receive an increased precipitation which, of course, would be one of the factors necessary to renewed glaciation. In this connection, it is noteworthy, perhaps, that in the Olympic Mountains, which receive a heavy precipitation, permanent snow and ice‐fields are rather general above an altitude of five thousand feet. Farther east in the same latitude, the present lower ice‐limit rises as the precipitation decreases. In Glacier Park it is at least seven thousan