1804 Dec. 643 We..must endeavour to ascertain, not only the rock formation in which it [sc. a fossil] occurs, but also its repository.
1917 3 659 Recent monographs.., dealing with certain rock formations in Switzerland, put new emphasis on an important problem in minerogenesis.
1992 1 Feb. 48/1 Huge boulders sometimes lie where they do not belong, far from their native rock formations.