Observations with respect to the nature and classification of the tertiary rocks of Australasia.

Abstract

General features of the Tertiary System: Overlying the prevailing sandstones, limestones, shales, and coal beds of the Mesozoic Period are to be found vast accumulations of clays, sands, gravel, marls, calcareous grits, limestones, gypsum, and lignites, of either marine or fresh-water origin. These accumulations, as a rule, do not present the same features as those of the older rocks, inasmuch as the process of consolidation and metamorphism, excepting in rare instances, is far less complete. The rocks generally are loose and incoherent, and their exposed surfaces are less able to resist the weathering and denuding influences of air and water.