Page:Popular Science Monthly Volume 85.djvu/85

Rh U-shaped valley. As the glacier receded, torrential streams cut into the glacial moraines, changing the vicinity of the upper reaches of the Merced into more angular surfaces, with the ultimate purpose of eliminating U and substituting V.

After all the theories have been advanced, their truth or fallacy will remain a matter of conjecture until the underlying facts are brought to light. Buried far below the flowery meadows and boulder overburden lies the unseen, pristine bed rock. Graven on tablets of stone in indelible characters is the key to the cryptic cipher of this Sierran Sphinx. The mining geologist is more practical than academic. He would prospect the floor of the valley to unearth that hidden key. Therefore, he would advise the sinking of shafts down through the sediments, ascertaining their character and striking the sunken sill. Following the rim of the latter for a short distance, the miner-geologist would soon determine in finality the genesis of the Yosemite Valley. If this deep basin was once shattered by a cataclysm, causing the falling away of an almost bottomless abyss, the zones of its marginal fracturing could be definitely discovered. Or, if overdeepening of the bed rock by the abrasive-shod plow of a glacier be the true cause of its carving, the striated strata and the morainal drift will tell the tale. Stream-erosion will also be revealed to its exact extent. Therefore, it would seem that no appropriation for the researches of the Geological Survey in this region can be expended to better advantage than by prospecting in miner-like fashion for the hidden truth of the making of this great natural wonder. That this practical idea meets with the approval of the Geological Survey party is shown by a recent expression by Mr. Francois E. Matthes in the Sierra Club Bulletin. "It is to be hoped that some day such borings may be undertaken; they would not merely serve to solve a problem of great local interest, but would contribute much-desired data regarding the still-challenged eroding efficiency of glaciers."

One of the most interesting features of the federal government's participation at the Panama-Pacific International Exposition will be the presentation of a large relief model of the Yosemite National Park. Cartographers of the United States Geological Survey are putting the finishing touches on this miniature of the Yosemite Valley and its surroundings. They will show its stupendous steeps and glaciated basins as vividly as though viewed from an aeroplane. Every visitor to the Exposition who may be interested in geological science will find this replica replete with fascinating details carefully set forth.

Buffalonians laid special stress upon the nearness of Niagara Falls to the Pan-American Exposition. Likewise, Californians take great