Geomorphic Occurrence of Pelloxererts, Willamette Valley, Oregon1
- R. B. Parsons,
- L. Moncharoan and
- E. G. Knox2
Documentation of the time factor in the genesis of Vertisols in western Oregon is provided by this study of Bashaw soils on four geomorphic surfaces that range in age from Holocene to middle Pleistocene. Bashaw soils are in a very fine, montmorillonitic, mesic family of Typic Pelloxererts. Although these soils have slickensides and high clay contents, they lack gilgai microrelief and tonguing between the A and C horizons. Stratification in the parent alluvium has not been obliterated by churning, suggesting that one annual cracking and closing cycle will not produce all of the morphological features commonly associated with Vertisols. Pedons from surfaces only 550 years old have developed sufficiently to be classified as Xererts. Morphological, chemical, and physical data indicate that the pedons studied are similar enough to lie within the range of one soil series. This study shows that Xererts occur on very young landscapes and that very little change takes place with increasing age.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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