The characteristic feature of all faults is displacement. But faults are finite, they must die out downward as well as laterally, and many faults originally failed to reach the surface. Displacement thus becomes zero at the margins of the fault plane, and must, therefore, vary, not only across the direction of movement, but also parallel to it. This paper deals with this variation as observed in cross-section—that is, in general, parallel to the direction of movement—and its relation to the origin and the magnitude of thrust faults.
In faulting, a large amount of deformation, or strain, is limited to a single plane. This paper also considers the problem of localization of causative stress which so concentrates the deformation.
Study of the structure of the foothills of the Rocky Mountains in Alberta, during the field seasons of 1929 and 1930, permitted the careful observation of many low-angle and . . .