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 History Museum at the University of Oslo Garden contains 35,000 plants, 7,500 species and two exhibition greenhouses. The Geological Museum contain research material of more than 2 million fossils, rock specimens and minerals. A selection of specimens are on display in both the Geological Museum and the Zoological Museum. Among the attractions is the "Darwinius masillae" fossil "Ida", a primate from the Eocene Epoch. Natural History Museum at the University of Oslo The Natural History Museum at the University of Oslo (, NHM) is Norway's oldest and largest museum of natural history. It is situated in the neighborhood of Tøyen in Oslo, Norway. It traces its roots