Mazama; A Record of Mountaineering in the Pacific Northwest ... Volume 1, Nos. 1-2

Mazama; A Record of Mountaineering in the Pacific Northwest ... Volume 1, Nos. 1-2

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1896 edition. Excerpt: ... A large mass of ice descended the valley next south of Llao Rock, reaching far down over the broad stream of basalt from Red Cone. The lavas are deeply planed off and striated, but the effect of glacial erosion upon the general topography is not so marked as upon the southern side of the Lake where deep U-shaped canyons have been cut in the older lavas. That the volcano was active at intervals during the glacial period is well shown by the glaciated flow of Round Top, upon the northeastern edge of the rim. This flow is overlain by two layers of pumice separated by a sheet of rhyolite, all of which were erupted after the glaciation of the surface upon which they rest. The eruption must have been accompanied by great floods from the snowcapped mountain. Such floods would account for the fact that all the valleys radiating from Crater Lake have been extensively filled with sediments. Reference has already been made to the occurrence of glacial striae on the very crest of the rim. They may be seen in many places along the crest northwest of Victor Rock; also a few miles beyond in the sag of the rim next southwest of Llao Rock, as well as near its summit. They occur also in Round Top, in Kerr Notch and over Eagle Crags, completing the circuit of the Lake from which they radiate. The topmost rocks of the crest are planed off and well striated upon the outer slope, but not upon the steep broken surfaces which they present to the Lake. Glaciation is a feature of the outer slope only, and it is evident that the ice armed with stones to scratch these rocks must have come from above, that is, from a peak which once stood upon the site of the Lake. In the deep U-shaped canvous of Sun and Sand Creeks, there is evidence to the same effect. They more

Product details

  • Paperback
  • 189 x 246 x 5mm | 181g
  • United States
  • English
  • black & white illustrations
  • 1236954157
  • 9781236954152