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Show CHAPTER II. STEUOTUEAL GEOLOGY. Homology of faults and monoclinal flexures.â€"Their systematic arrangement.â€"Those of the High Plateaus helong to the same system as those of the Kaibabs.â€"The Grand Wash fault.â€"Hurri-ricane fault.â€"Tushar fault.â€"Toroweap fault.â€"Sevier fault.â€"Western and Eastern Kaibab faults.â€"Thousand Lake fault.â€"Musinia faults.â€"Age of these displacements.â€"Their relative recency.â€"Difficulty of assigning their periods in definite terms.â€"Argument of recency from amounts of erosion.â€"Argument from the amounts of accumulation of valley deposits.â€"Age of the faults with reference to evidences of glaciation.â€"Importance of knowing the ages of these faults.â€" Some are more recent than others.â€"An older system of faults of Cretaceous-Eocene age.â€"Water-Pocket flexure.â€"San Eafael flexure.â€"Parallelism of recent major faults to the old Cretaceous-Eocene shore-line.â€"Evidences of recent uplifting in the canons.â€"Comparison of structural forms in the three provinces, the Basin, the Plateaus, and the Parks.â€"Types of the Parks.â€"Effects of erosion upon structure.â€"Absence of horizontal forces in the elevation of the Plateaus. The great structural features of the High Plateaus are the faults and monoclinal flexures. Faulting is an almost universal concomitant of great disturbances of the strata and of the uplifting of mountains and plateaus. Of their causes geology has taught us but little beyond the bare fact that they are produced in the great majority of cases by differential uplifting by vertical forces, which is hardly more than an identical proposition. The nature of the forces we know not, and can only speculate vaguely about them. We do not always know even whether a fault is produced by uplifting upon one side of a given vertical plane or by sinkage on the other, and there must always be an implicit reservation when we speak of them as produced by upliting, so that nothing more is meant than that the strata have been sheared vertically, and that one portion is left on a higher plane than the other. Why the vertical forces should undergo an abrupt change or even total extinction in passing from one side of a given line to the other is a mystery which we cannot hope to solve until we know the origin of the force itself. All that is left us at present is to study the faults themselves carefully, ascertaining, as far as practicable, what movements have 25 |
