|The Wave, a sandstone formation in northern Arizona.|
“The Wave” consists of intersecting U-shaped troughs that have been eroded into Navajo Sandstone of Jurassic age. The two major troughs, which comprise this rock formation, are 19 meters wide by 36 meters long and 2 meters wide by 16 meters long. Initially, infrequent runoff eroded these troughs along joints within the Navajo Sandstone. After their formation, the drainage basin, which fed rainwater to these troughs, shrank to the point that the runoff became insufficient to contribute to the cutting of these troughs. As a result, the troughs are now almost exclusively eroded by wind as indicated by the orientation of erosional steps and risers cut into the sandstone along their steep walls. These erosional steps and risers are oriented relative to predominate direction of the wind as it is now naturally funneled into and through these troughs.
The Wave exposes large, eolian sets of cross-bedded sandstone composed of rhythmic and cyclic alternating grainflow and windripple laminae. The rhythmic and cyclic alternating laminae represent periodic changes in the prevailing winds during the Jurassic as huge sand dunes migrated across a sandy desert. The thin ridges and ribbing seen within The Wave are the result of the differential erosion of rhythmic and cyclic alternating grainflow and windripple laminae within the Navajo Sandstone. These laminae have differing resistance to erosion as they have been differentially cemented according to variations in the grain size of the sand composing them. The soft sandstone, including the ridges and ribbing, of The Wave is fragile. As a result, a person needs to walk carefully to not break the small ridges.
In places, The Wave exposes deformed laminae within the Navajo Sandstone. These laminae were deformed prior to the lithification of the sand to form sandstone. Judging from their physical characteristics, this deformation likely represents the trampling and churning of these sands by dinosaurs right after their deposition. Dinosaur tracks and the fossil burrows of desert-dwelling arthropods, such as beetles and other insects, have been found within the Navajo Sandstone within the North Coyote Buttes Wilderness Area.Note : The above story is based on materials provided by Wikipedia