Cambic and Certain Noncambic Horizons in Desert Soils of Southern New Mexico

Abstract

AbstractIn a study area of southern New Mexico, horizons in the B position may be ordered in degrees of increasing development, and form an essentially continuous series closely related to age. No evidence of soil development is found in freshly deposited arroyo alluvium. Next in the developmental scale are horizons with some weak evidence of soil formation, but which are still too weakly developed to qualify as cambic horizons. With increasing age, cambic horizons and finally argillic horizons occur in the B position. The relationships of soil development to age are confounded in some older soils by such factors as soils truncation and soil mixing.Distinct cambic horizons have formed in soils that are less than about 5,000 years old. In various cambic horizons there has been sufficient alteration of the original parent material to destroy fine strata, form structure, develop redder color, redistribute carbonate, and accumulate slight amounts of silicate clay. Cambic horizons of old, polygenetic soils show evidence of profound change in the B position since deposition of the parent materials and the start of soil formation. Argillic horizons apparently formed in some soils and were later destroyed. Some soils once had much thicker B horizons than they now have.The present climate of this desert region is arid, but evidence of former glaciation and lakes indicates a climatic change. The present climate is apparently warmer and drier than the climates of Pleistocene pluvials. Soils formed mainly in the Pleistocene tend to have thicker, stronger horizons than do soils formed in the Recent; this is apparently caused in part by the Pleistocene pluvial climates.