Beach Drainage

January 24, 2017

Coronadelmar241216_5dendrites (2)

Photographer: Dale Chadwick
Summary Authors: Dale Chadwick; Jim Foster

This photo looks like it could have been transmitted by one of the Mars rovers. However, it was snapped on Corona Del Mar's beach in southern California. Ocean water receding to the sea, after lapping ashore, created this tiny drainage pattern. Note also the miniature braided channels.

CaptureThe photo at left shows a similar pattern, but at a large scale, on a snow covered mountainside near Castle Dale, Utah. Tree-like dendritic shapes are typical of many drainage basins, regardless if they're a few feet across or hundreds of miles across. This is the pattern that occurs when water drains off slopes underlain by homogeneous rock masses that have a more or less horizontal expression, sedimentary rock layers for example, and where erosion is rather uniform. Tributaries flowing into larger channels tend to form at acute angles, resulting in the dendritic pattern. Top photo taken on December 24, 2016; inset photo on December 29, 2016.

Photo Details: Canon EOS 80D camera; 1/40 sec. exposure; f29.