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Show X GEOLOGY OF THE HIGH PLATEAUS. zones of diverse displacement: these districts are broken into smaller blocks by faults and flexures, and often the blocks have been excessively tilted and warped in diverse directions. On the flanks of plateaus and mountain systems of the Uinta type where monoclinal flexures occur mono-clinal ridges are frequently seen. The position of these monoclinal ridges is frequently varied by the occurrence of transverse faults. Where a great Kaibab, Uinta, or anticlinal upheaval is found broken by a transverse fault, that portion of the grand upheaval which has the greater amplitude will have its monoclinal ridges placed more distant from the axis of upheaval and that portion which has the less amplitude will have its monoclinal ridges nearer the axis. In this manner, by vertical movements in transverse faulting, the monoclinal ridges may be placed back and forth from the axis of grand upheaval in such a manner as to give the appearance of lateral faulting, i. e., faulting in a horizontal direction. On the plateaus stand buttes, lone mountains, and groups of mountains. The buttes are mountain cameos, composed of horizontal strata with escarped sides-they are mountains of circumdenudation. The mountains are composed in whole or in part of extravasated matter and may be classed structurally under three types. I. Those having the Henry Mountain Structure-where the locus of vol- canic deposition is below the base level of degradation. II. Those having the Tushar Structure-where the locus of volcanic deposition is at the base level of degradation. III. Those having the Uinkaret Structure-where the locus of extravasation is above the base level of degradation. In the first, the mountains are composed in part of volcanic and in part of sedimentary materials. The volcanic matter exists as laccolites, over which sedimentary strata have extended in great mountain domes, but such strata may have been carried away, more or less, by atmospheric degradation. In this class each mountain is a mass of volcanic material, witli sedimentary beds upon its flanks, and often these sedimentary.beds extend high up ,or even quite over the volcanic materials. In the second, the mountains are composed wholly of volcanic materials erected upon a base of sedimentary strata. The mass is composed of |