Rock.

Rock. Though popularly restricted to masses of indurated matter, this term is extended by geologists to all substances which make up the crust of the earth, whether they be loose and friable like soil and sand, or compact and indurated like limestone and granite. The rocks of the earth's crust (aqueous, igneous, metamorphic, &c.) will be found described under numerous distinct headings in this work. See the classification given at PETROGRAPHY, and the article GEOLOGY, with the list appended, including such articles as DENUDATION. See also BUILDING STONE, BLASTING, BORING.