. Vegetation of Oregon and Washington. Botany Oregon Ecology; Botany Washington (State) Ecology. Figure 9. — An area of Cretaceous sedimentary rock (Swauk sandstone) northwest of Wenat- chee, Washington; the steeply tilted beds of sandstone are clearly visible in this area of highly erodible soils. Soils developed from glacial materials differ considerably, depending on whether they are derived from indurated till, loose outwash, and morainal materials or from fine-textured lacustrine deposits. Another important factor is the rapid pace of geologic erosion on steep slopes, which in many areas
. Vegetation of Oregon and Washington. Botany Oregon Ecology; Botany Washington (State) Ecology. Figure 9. — An area of Cretaceous sedimentary rock (Swauk sandstone) northwest of Wenat- chee, Washington; the steeply tilted beds of sandstone are clearly visible in this area of highly erodible soils. Soils developed from glacial materials differ considerably, depending on whether they are derived from indurated till, loose outwash, and morainal materials or from fine-textured lacustrine deposits. Another important factor is the rapid pace of geologic erosion on steep slopes, which in many areas restricts soil for- mation to the extent that Lithosols and Rock- lands are common. Very little specific soils information is a- vailable for the province. However, a soil sur- vey of a limited area (Gilkeson et al. 1961) identified several Podzol soil series derived from basalt and andesite colluvium and glacial drift. These soils have a 3- to 8-centimeter- thick, grayish, A2 horizon of sandy loam or loamy sand texture. The underlying soil is brown to reddish brown as a result of iron staining and is generally gravelly silt loam in texture. With the exception of soils formed on indurated glacial till which were classed as imperfectly drained Podzols, all soils in the area were well drained. The most widely distributed great soil groups in the Northern Cascades province are Podzol, Brown Podzolic, and Lithosol. Other, less abundant soils include Rocklands and Regosols. In subalpine areas, the most com- mon soils are Alpine Turf, Rockland, and Al- pine Meadow. In the drier, southeastern por- tion of the province, Western Brown Forest, Gray Wooded, Chestnut, and Lithosol soils re- place the podzolic soils found in higher rain- fall areas. Southern Washington Cascades Province The Southern Washington Cascades prov- ince extends south from Snoqualmie Pass to the Columbia River. Unlike the Northern Cas- cades, andesite and basalt flows dominate with only minor amounts of igneous i
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