. Vegetation of Oregon and Washington. Botany Oregon Ecology; Botany Washington (State) Ecology. rocks of this province probably include the oldest in Oregon. The Klamath Mountains province is largely a region of rugged, deeply dissected terrain (fig. 5). Mountain crests, comprised of steeply folded and faulted pre-Tertiary strata, vary in elevation from 600 meters near the coast to approximately 1,200 meters in the east. Ridge accordance suggests an ancient and now great- ly dissected peneplain. Many peaks rise above this summit peneplain. The highest of these monadnocks in Oregon is 2,280-me
. Vegetation of Oregon and Washington. Botany Oregon Ecology; Botany Washington (State) Ecology. rocks of this province probably include the oldest in Oregon. The Klamath Mountains province is largely a region of rugged, deeply dissected terrain (fig. 5). Mountain crests, comprised of steeply folded and faulted pre-Tertiary strata, vary in elevation from 600 meters near the coast to approximately 1,200 meters in the east. Ridge accordance suggests an ancient and now great- ly dissected peneplain. Many peaks rise above this summit peneplain. The highest of these monadnocks in Oregon is 2,280-meter Mount Ashland which rises 1,060 meters above the general level of its surroundings. The geologic history of the Klamath Moun- tains began during the Paleozoic era with dep- osition of volcanic tuffs and sedimentary rocks which were subsequently metamor- phosed, largely into schists. A period of ero- sion and folding followed until late in the Tri- assic period when a large series of volcanic and sedimentary rocks were deposited near Medford and Grants Pass. These rocks have all undergone extensive metamorphism into vari- ous types of schists, gneisses, marbles, and other metavolcanic or metasedimentary rocks. These rock types outcrop east of Gold Beach and at other scattered locations throughout the province. During the Jurassic period, sand- stones, siltstones, and shales were laid down along the coast and in a belt extending from the southwestern corner of Oregon across the province in a generally northeasterly direc- tion. Most of these deposits have undergone very little alteration. These rock strata were in- truded with ultramafic rocks such as peridotite and dunite during late Jurassic or very early Cretaceous times. The intrusions have largely been altered to serpentine which now appears in elongated, stringerlike outcrops, generally associated with fault zones. Other rocks which were intruded at approximately the same time include a variety of granitics — diorite,
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