Erosional Origin of the Great Basin Ranges

Abstract

It is not at all probable that the origin of the mountain ranges of the Great Basin of western America can find adequate and satisfactory explanation by a single simple hypothesis. Nor can it be advantageously postulated that the genesis of the mountains is the same in the various parts of that vaster desert region of which the Great Basin is only a minor portion. In general all recent observations go to show that these mountains as they exist today must be regarded as the outcome of the action of several sorts of geologic forces, operating sometimes severally and sometimes in conjunction, at diverse times and with different degrees of intensity. The relative ascendency of the several geologic processes in shaping the larger relief features of the desert region has remained until recently an indeterminate quantity. It is this aspect of the subject that has been all but entirely overlooked. This neglect has led to very divergent opinions, as is shown by a full dozen of distinct hypotheses advanced to explain the origin of the Basin ranges. In the consideration of the origin of the American desert mountains, it is usually assumed that they are strictly structural features. That they may have been fashioned, partly at least, by other means is a suggestion which is only beginning to attract the attention which it merits. Present indications are that erosioneolian erosion-must be reckoned with as one of the potent factors in desert sculpturing. Many descriptions of the Great Basin ranges have been published. Notwithstanding this fact there has not yet appeared, as Davis' well says, any detailed statement of the theory by which they are explained; the essential consequences of the theory have not been explicitly formulated; the criteria by which a fault-block mountain may be recognized in early or later stages of dissection have not been defined.