The geologic structure of the arid region comprising the Great basin of western America and the northern part of the Mexican tableland is supposed to be characteristic of that anomalous class of geotectonics known as the Basin Range, or Block Mountain, type. Its distinctive feature is commonly considered as the product of normal faulting on a prodigious scale. Lately, the long accepted opinions regarding the Basin Range structure have been brought seriously into question. As a result a new interest in the subject has been kindled.
That the tectonics of the regions mentioned have never received the careful consideration that the natural advantages for study would seem to demand is due partly to a singular notion which has prevailed from the first, that these regions present structures of great simplicity and hence require little detailed examination.
Physiographically the dominant feature of the Great basin and the Mexican tableland is . . .