There are jagged rocks and cliffs and many bays and inlets. Mageik stands on the same sedimentary rocks as Martin. They threw scores of MacDonald women over cliffs to their deaths on rocks below. Sedimentary rocks overlay most of these ancient rocks. Agates are most commonly found as nodules within the cavities of volcanic rocks. Shungite may also occur as clasts within younger sedimentary rocks. These barriers are made out of concrete, rocks or earth. Extrusive igneous rocks cool and solidify more quickly than intrusive igneous rocks. The crowd grew threatening, throwing snowballs, rocks, and debris at them. These minerals formed during the crystallization of igneous rocks. Quartz is a defining constituent of granite and other felsic igneous rocks. Texture is an important criterion for the naming of volcanic rocks. About 10% of sedimentary rocks are limestones. It is a common constituent of schist, gneiss, quartzite and other metamorphic rocks. To boil the water hot rocks were used.