Page:Popular Science Monthly Volume 30.djvu/12

2 feet below the present snow-line. Mount Rainier still carries a dozen glaciers of considerable size, and all the country is glaciated about this and the other snow-peaks of Washington Territory, Mount St. Helen's, Mount Baker, Mount Adams, Mount Olympus, etc., around Puget's Sound, and on Vancouver's Island. In British Columbia, as shown by George M. Dawson, Dr. Hector, James Richardson, and others, the signs of ancient glaciation are conspicuous in all the high country explored. Along the coast farther north the ancient glaciers have left their marks in all the fiords, and those of the present day descend lower and lower until in Alaska they reach the sea-level.

The valleys of the Wahsatch range were once filled with masses of ice as far south as Central Utah. A type of these, though not the largest, was Little Cottonwood glacier, of which the record has been carefully studied by the writer. It formed in a cirque at Alta ten to eleven thousand feet above the sea, where its bed is everywhere conspicuously glaciated. It had a length of about ten miles; its thickness, as shown by the line of granitic blocks, left along its sides, was five hundred feet or more, and its lower end protruded into the Salt Lake Valley at a level not greater than fifty-five hundred feet above the ocean. The glaciation of the Uintah Mountains has been graphically described by King, who says that all the higher portions of the range were once covered with a continuous sheet of snow and ice, and that glaciers descended through all the important valleys; also that the ancient glaciers of the Uintahs occupied a greater area than all those now existing in the Alps.

In the Rocky Mountain belt the signs of ancient glaciers abound from the northern part of New Mexico through Colorado and along the great divide in Wyoming, Montana, and Idaho. In the valley of the Arkansas, particularly about Leadville, in the Parks, on Clear Creek, in the valley of the Rio Grande, roches moutonnées, lateral and terminal moraines, embankment-lakes, etc., all the work of glaciers, have been observed by thousands of travelers. Here the mountain-belt is very broad and high, is now the great condenser from which radiate all the most important streams of the West, and in winter is covered with a heavy sheet of snow. In ancient times it played a similar rôle, only that the snows of winter did not melt as now in summer, but accumulated from year to year until they produced great glaciers. In Wyoming the mountains are narrower and lower, and the glacial signs are less conspicuous; but toward the British line, where the ranges multiply and the summits are higher, the records of glaciation are everywhere apparent.

To summarize the description of the glacial phenomena of this Western region, it may be said that, over all the mountain-ranges north of the limit before given, the traces of ancient glaciation are alike in character and apparently of the same date, and are evidently the effects of general and not local causes.