Igneous rock the partial melting of rocks within the mantle and crust. Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks. They are formed by the cooling of molten magma on the earth's surface. The magma, which is brought to the surface through fissures or volcanic eruptions, solidifies at a faster rate. Hence such rocks are smooth, crystalline and fine-grained. Basalt is a common extrusive igneous rock and forms lava flows, lava sheets and lava plateaus. Some kinds of basalt solidify to form long polygonal columns. The Giant's Causeway in Antrim, Northern Ireland is an example. The molten rock, with
Natural Trap Cave become an experiment in taphonomy, in that its body has been allowed to lie undisturbed so as to study natural patterns and rates of decay. Natural Trap Cave Natural Trap Cave is a pit cave in the Bighorn Mountains, in northern Wyoming, United States. Excavations in the cave are an important source of paleontological information on the North American Late Pleistocene, due to a rich layer of fossils from animals that became trapped in the cave. The cave is located northeast of Lovell, Wyoming, at an elevation of . It is a bell-shaped pit or sinkhole within the Madison Limestone,