. Elements of geology : a text-book for colleges and for the general reader. Geology. FISSURES, OR FRACTURES. 231 sequent erosion, so that the unpractised eye detects nothing unusual along the line of fracture and slip. In Fig. 198 the strong line a a shows the present surface, while the dotted line bbb shows the surface after the displacement as it would be if unaffected by erosion. In many cases, however, it seems more probable that there never existed any such escarpment as represented in Fig. 198, but that the displace- Fig. 200.âSection through Portion of Plateau Pegion of Utah, showing a
. Elements of geology : a text-book for colleges and for the general reader. Geology. FISSURES, OR FRACTURES. 231 sequent erosion, so that the unpractised eye detects nothing unusual along the line of fracture and slip. In Fig. 198 the strong line a a shows the present surface, while the dotted line bbb shows the surface after the displacement as it would be if unaffected by erosion. In many cases, however, it seems more probable that there never existed any such escarpment as represented in Fig. 198, but that the displace- Fig. 200.âSection through Portion of Plateau Pegion of Utah, showing a Succession of Faults (after Howell). ment was produced by a sloiv, creeping motion, or else by a succession of smaller sudden slips probably accompanied with earthquakes (p. 113), and thus that the slipping and the denudation have gone on to- gether pari passu. In Fig. 227, on page 255, the upper part shows the great Uintah fault restored, while the lower part shows the actual condition of things produced by erosion. When faults. Fig. 201. oc_ ,«,.!.âFault with Change of Dip : d, dike. cur in inclined outcropping strata, the same series of strata may be re- peated several times, as in Fig. 199. In such a case, the observer walk- ing over the surface of the country from A to B might suppose here a series of nine strata, whereas there are ':;.â¢.â¢'.â â¢':::â¢.â¢â¢â¢â .â â â ;': \:^^\-".7 â¢-/â¢': â¢;:/.â ;. but three strata, a, b, c, three times re- peated. Fig. 200 is a natural section showing this. Sometimes the dip of the strata on the two sides of a fault are not parallel, the change of inclina- tion being effected at the time of the displacement, as shown in Fig. 201. Upon the eroded surface of such dis- located strata, by subsequent subsi- dence, other strata may be unconformably deposited (Fig. 202). Law of Slip.âIn faults the plane of fracture is sometimes vertical, but much more generally it is more or less inclined. In such c
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