Rhythmite

A rhythmite consists of layers of sediment or sedimentary rock which are laid down with an obvious periodicity and regularity. They may be created by annual processes such as seasonally varying deposits reflecting variations in the runoff cycle, by shorter term processes such as tides, or by longer term processes such as periodic floods.

• http://en.wikipedia.org/wiki/Rhythmite
• https://www.google.com/maps/d/u/0/viewer?mid=14YY3J0HLMehpL22SVtE7LYReVC80PyxR&hl=en&ll=47.0280363330574%2C-114.38396671905406&z=19