SOILS DEVELOPED FROM BASALT IN WESTERN COLORADO

Abstract

The characteristics of soils developed from basalt under successive climatic-vegetation zones from desert to high spruce forest were studied at altitudes of 5000-10,800 ft. Soils with distinctly different characteristics have developed in each zone. Drainage is good in all these soils, which are mostly mature. The thickness of the A horizon increases from 6 to more than 16 inches with increasing altitude. The pH decreases from 8 in the desert to an extreme of 4.5 under spruce above 10,400 ft. Organic matter increases from 1.3% in the desert to 6% on the Grand Mesa. Subsoil development tends towards claypans reaching a max. development on the mesa. Some soils developed from recent glacial till have not developed clay subsoils.