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
The Columns (Columbia, Missouri) At the beginning of the academic year, freshmen participate in Tiger Walk to symbolize their move from the wider community to the university by walking through the columns. Tap Day occurs under the columns, when the schools secret societies announce their new members. A mural of James S. Rollins and the Columns is located in the office of the Missouri Governor in the Missouri State Capitol. The Columns are also featured in the Missouri House in a monumental stained-glass window titled "Missouri at Peace". A mural by George Caleb Bingham depicting Academic Hall was destroyed when the same burned. Academic