Abstract
The sediments that cover the surface of the earth are usually laid down in a horizontal or near-horizontal position and frequently remain that way. Occasionally within these layers are somewhat vertical cracks filled with different kinds of sediments. These vertical foreign bodies of sediments penetrating the horizontal sedimentary layers are called clastic dikes (Figure 1). The size of the dikes can vary in thickness from a few centimeters to hundreds of meters; their height is usually several times greater than their width. Often the sediments in the dikes come from other sediments found below the intruded layers. The process of formation is analogous to wet sand oozing up between one's toes, only on a larger scale.