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
Callao Cave and a height of . The cathedral-like room has been turned into a chapel by the local people. A rock formation serves as the altar of the chapel lit by a stream of light coming from a rooftop opening. The conditions inside the caves have caused the formation of stalactites and stalagmites, more so in the deeper chambers. Several spectacular speleothems or formations are found inside the cave like flowstones, glittering dripstones, cave curtains, crystal helictites, columns, etc. Callao Cave is classified by the Department of Environment and Natural Resources as a Class II cave. This describes caves with areas