'Shaler' unit's evidence of stream flow

Inclined layering known as cross-bedding appears in an outcrop nicknamed "Shaler" on a scale of a few tenths of meters. NASA says the cross-bedding evident in the Shaler location is indicative of sediment transport in stream flows, hinting at past flowing water. Currents may have molded these sediments into small underwater rifts or dunes that then move downstream. When exposed in cross-section, evidence of this migration is preserved as strata that are steeply inclined relative to the horizontal -- thus the term "cross-bedding."

Wind formation has been ruled out here because the grain sizes are coarse enough that the formations are formed by currents, not by wind, NASA believes.