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
Cave S it was covered in a soil that had the consistency of snuff in 1910. Despite not finding any bats he thought that the snuff-like material was vegetable matter and bat guano. Various human artifacts such as pottery, stone implements and other stone objects, a shell armlet, perforated cyprcea, charcoal, burnt bone and broken shellfish and a wide variety of bird remains and mammalian fauna have been found in the cave. The human bones were thought to come from one male skull-less skeleton which appeared to have notably thick bones. Cave S Cave S is a limestone cave in the British