A body of rock that cuts across the layers of its surroundings. Most dikes are made of magma, but some are made of sediments. The sandstone dikes were put emplaced as hydrocarbons and gases moved into the thick sand bed soon after it was buried and the sand dike rose into the overlying mud while all of the material was not yet hardened into stone. What defines a dike is that it cuts across the bedding planes of the rock it intrudes. When an intrusion cuts along the bedding planes, it is called a sill. In a simple set of flat-lying rock beds, dikes are vertical and sills are horizontal