Granite is a common and widespread igneous rock, formed by the slow cooling of immense chambers of magma (molten rock) deep within the earth. Weathering, the action of wind, water and organisms at the earth's surface, may strip away overlying materials and expose these hardened magma chambers to surface conditions. Granite is unusual in that weathering often causes the rock to disintegrate in a spherical pattern, known as spheroidal weathering. On a very large scale, this can produce immense rounded features such as Half Dome in Yosemite Park, California.