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Show a. st. Fignro 76.-Scction throngb Echo Cliffs. OLJlt'FS OF DISPLAOEMEN'£ AND EROSION. 191 or, if we arc to consider the di~placement as caused by upheaval, the blocks uplifted have their lines of cliffs set farther back to the north; and the amount of this backward or forward displacement is in direct ratio to the amount of vertical diHplacomont in tho fault or monoclinal fold The higher region has suffered a greater amount of erosion, and as erosion progresses ·· chiefly by undermining, as I have explained in tho discussion of the Terrace Canons, the cliffs of tho higher blocks stand farther back from the axis of upheaval than those of tho lower blocks. The general line of these cliffs is broken in another way. Streams, heading on the high plateaus to the north, run southward into the Grand Canon, and have carved out canons through tho cliffs, and turned the escarpment far back into the several benches, so that instead of four unbroken walls facing the south, and having an easterly and westerly direction, we have, in fact, a series of salients and re-entering angles. Entering this country from the east or west, it is necessary to climb great benches, due to displacements along faults, and crossing it from south to north, it is necessary to climb great benches, but those are duo to erosion; so we have two systems of cliffs- cliffs of displacement, having a northerly and southerly trend, and cliffs of erosion, having an easterly and westerly trend. The first-cliffs of displacement- are of two classes: those facing the west, where the throw of the beds is on the western side of the fractu re, and those facing the east, whore the throw of the beds is on the eastern side of the fracture. The cliffs of erosion are very irregular in direction, but somewhat con-stant in vertical outline; and the cliffs of displacement aro somewhat regular in direction, but very inconstant in vertical outline. This inconstancy is due to the frequent changes in the character of the faults, which I have previously described. In the Echo Cliffs, east of Marble Canon, a line of cliffs, due to oro-· sion, and a slope due to displacement, have come together, back to back. The position of the slope is essentially unchangeable, as it is due to a flexure; but tho escarpment, due to erosion, has donbtless been carried back from Marble Canon to the east, until it bas just reached this slope. Figure |