English: Modern curled mudcracks in Arizona, USA. (3 September 2007)

Mudcracks are diagnostic sedimentary structures indicating subaerial exposure of sediment surfaces, with alternating wet & dry conditions. They are much more common that raindrop imprints, which indicate the same environmental setting. Mudcracks are most likely to occur in fine-grained siliciclastic sediments, fine-grained carbonate sediments, and in some evaporitic settings.

Mudcracks are distinctive and easy to identify, but they do vary in appearance. The cracks themselves vary in width, depth, and areal density. Mudcrack polygons also vary in size & shape. The upper crusts of the modern examples seen here have curled upward as they dried.

Locality: near Tsegi overlook, southern rim of Canyon de Chelly, Canyon de Chelly National Monument, northeastern Arizona, USA