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
Canso Causeway employees operate the swing bridge across the Canso Canal. Canso Causeway The Canso Causeway ("Cabhsair Chanso" in Gaelic) is a rock-fill causeway in Nova Scotia, Canada. The causeway crosses the Strait of Canso, connecting Cape Breton Island by road to the Nova Scotia peninsula. Its crest thickness is , carrying the two vehicle traffic lanes of the Trans-Canada Highway, Nova Scotia Highway 104 on the mainland side, and Nova Scotia Highway 105 on the Cape Breton side, as well as the single track mainline of the Cape Breton and Central Nova Scotia Railway. Constructed in an "S" shape, the causeway