Mudcracks form where a layer of uniform fine sediment becomes desiccated. (more below)

It takes a very active environment, where sedimentation is fast, to preserve delicate features such as mudcracks. But here they are in young rocks at Weston Beach in Point Lobos State Park south of Monterey, California. The thickness of the mud layer affects the size of the desiccation cells?here the mud was more than 5 centimeters thick and left cells roughly the size of a handprint.