Soil-geomorphology relations in mountains of Oregon,U.S.A.

The development and distribution of soils in the Coast Range and Klamath Mountains are related to geomorphic surfaces and slope gradients. Soils over basalt, studied in the Coast Range, were formed in transported materials and include examples of more than a half dozen great groups of the Alfisol, Inceptisol, Mollisol, and Ultisol orders. Distribution patterns of the soils can be related to active slopes, metastable slopes, pediments, ridge tops, flood plains, and alluvial fans. Variables among the factors of soil formation in the Coast Range are chiefly geomorphic surfaces and parent materials.Soils of a lithosequence of pyroclastics, granite and schist in the Klamath Mountains include examples of great groups in the Entisol, Inceptisol, and Mollisol orders. All soils from pyroclastics have argillic horizons, those from granite lack argillic horizons, and those from schist lack argillic horizons except on relatively stable surfaces. Average thicknesses of soils over saprolite range from 76 cm over granite and schist to 150 cm over pyroclastics.Lithologic discontinuities are common in both mountain areas. Field techniques for identification, described briefly, include stone lines, irregular distribution of rock fragments with depth, thicknesses of weathering rinds on rock fragments, and the lateral extensions of soil horizons.