Читать книгу Trinity Alps & Vicinity: Including Whiskeytown, Russian Wilderness, and Castle Crags Areas. A Hiking and Backpacking Guide онлайн

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There is no evidence of volcanic lava flows or eruptions with the Klamath Mountains. Granitic magmas did well up at various times, which accounts for the composition of most of the higher peaks in the area. Other igneous rocks, known as mafic and ultramafic, also squeezed up into faults and cracks in the earth’s crust; the high iron content of much of this rock accounts for the weathered red- and rust-colored rock of many of the other high peaks in the region.

Further upheavals, lateral movements, and constant erosion over geologic time gave many of the lower ridges and canyons much of the same shape as they display today, but the higher peaks and ridges received their final contours during periods of glaciation. Although these glaciers ran down the canyons just a few miles, the massive sheets of ice removed cubic miles of rock from the higher areas, depositing the ground-up rock in the lower areas. Once the glaciers receded, they left behind many small cirque-bound lakes at the heads of U-shaped valleys, with fantastically carved divides between them. Moraines dammed some of the larger valleys, which formed large lakes and marshes that eventually became some of the present-day meadows; Morris Meadows in the Trinity Alps is an outstanding example. Erosion distributed glacial till farther down the canyons, putting the finishing touches on the landscape that is visible today. Elevations in this part of the Klamath Mountains range from 900 feet along the lower Trinity River to 9,002 feet on top of Thompson Peak.