Abstract

Eolian ripple marks, formerly supposed not preservable, were observed at eight localities in the Colorado Plateau, in the De Chelly, Wingate, Entrada, and Navajo sandstones. The ripple marks could be seen only when the sun struck the surface at a low angle, throwing the faint ridges into sharp relief. At one locality in the Entrada, the average wave length was 15 cm, height 0.4 cm, and ripple index 35. Average ripple indexes at the other localities ranged from 22 to 75(?). Shear ridges on subaerial sand do not produce eddies in the air, hence the ridges are built only by direct drag or bed shear. This limits their height and keeps the ripple index high.

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