Chevron (land form)

A chevron is a wedge-shaped sediment deposit observed on coastlines and continental interiors around the world. The term chevron was originally used independently by Maxwell and Haynes and Hearty and others for large, v-shaped, sub-linear to parabolic landforms in southwestern Egypt and on islands in the eastern, windward Bahamas.

The Egyptian “chevrons” are active, wind-generated dunes, but the “chevrons” in the Bahamas are inactive and have been variously interpreted. The most common interpretation of large, chevron-shaped bed forms is that they are a form of parabolic dune, and that most examples are generated by wind action.

Many chevrons can be found in Australia, but others are concentrated around the coastlines of the world. For instance there are chevrons in Hither Hills State Park on Long Island and in Madagascar (such as the Fenambosy Chevron), as well as in interior sites of the United States such as the Palouse region of eastern Washington State, the Great Sand Dunes National Park and Preserve, and White Sands National Monument.

According to Hansen et al. 2015, powerful storms and changes in sea level rise can explain chevrons, as the study elaborates: The lightly indurated ooid sand ridges are several kilometers long (Bahamas) and appear to have originated from the action of long-period waves from a northeasterly Atlantic source. The chevron ridges contain bands of beach fenestrae, formed by air bubbles trapped in fine ooid sand inundated by water and quickly indurated. The internal sedimentary structures including the beach fenestrae and scour structures (Tormey, 2015) show that the chevrons were rapidly emplaced by water rather than wind (Hearty et al., 1998). These landforms were deposited near the end of a sea level high stand, when sea level was just beginning to fall, otherwise they would have been reworked subsequently by stable or rising seas. Some chevrons contain multiple smaller ridges “nested” in a seaward direction (Hearty et al., 1998), providing further evidence that sea level was falling fast enough to strand and preserve older chevrons as distinct landforms.

...
Wikipedia