OCR Text |
Show GENERAL STRUCTURE OF THE TUSHAR. 173 toward the basin type. The latter may be represented by conceiving" the strata forming the platform of a given tract to be rent by a long fault, and upon one side of it to be lifted and tilted at a considerable angle. This inclined mass is usually further fractured by smaller faults rudely parallel to the principal one, and complicated by more or less warping. The plateaus also are usually tilted, the Aquarius and Kaibab being most nearly horizontal. But there is a marked difference between the two types in the amount of inclination. In the plateaus it seldom exceeds three degrees; in the basin it is rarely less than ten. In the plateaus the warping and minor displacements are seldom important, and the whole aspect is calm and even; in the basin they are extensive, and the aspect is wild and distorted. In the plateaus, the obvious characteristic features are the broad platforms of the tables, the gently sloping terraces and the majestic repose of the mighty cliffs which bound them; in the basin, they are the sharp ridges, cusp-like teeth, and tumultuous slopes of sierras. Probably the correct view to be drawn from a comparison of the two structures is that the basin type represents an advanced stage of an action which has been imperfectly developed in the plateaus. Had the tables been pushed up higher, they might have been as much inclined as the sierras and as much comminuted and distorted. The Tushar is in some portions at least, and so far as observed in most portions, more inclined than any other of the High Plateaus, but so far as can now be discerned it approaches more nearly to the tabular than to the sierra type. Lying within the geographical limits of the Great Basin, it is not surprising that it should show an approach to the structure of the latter province. It may be regarded as indicating a transition between the two forms, though more nearly allied to those peculiar to the Plateau Province. It is difficult, however, to realize this conclusion as being a true one when we stand upon the southern termination of the Pavant, and look at the cluster of peaks which crown the summit of the Tushar. Two noble cones ending in sharp cusps stand pre-eminent, while behind them numerous dome-like masses rise to nearly the same altitudes. The two peaks are Belknap and Baldy, which reach above the timber-line, and are very striking on account of the light cream-color of their steep slopes and the ashy-gray tips of the apices. These pyramids are not apparently the remains |