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
Prometheus Cave Natural Monument Prometheus Cave Natural Monument Prometheus Cave Natural Monument () also known as "Kumistavi Cave" () and "Tsqaltubo Cave" () is a karst cave located in Tsqaltubo Municipality in Imereti region of Georgia. The total length of the cave is about 11 km, of which 1060 m are open to visitors. Cave has total of 22 halls of which six are currently open to tourists. The cave was discovered and studied by Georgian speleologists in the early 80's of the 20th century. It is part of a large cave system, united by one underground river. Currently, about 30 km of the