. Geological magazine. at vertical pressureshave exceeded horizontal pressures, (arguing as above) we shouldhere exj)ect to meet with direct faults; but since it is certain inhighly contorted and cleaved strata, as in the English and Welshslates, that horizontal pressures have at one time far exceeded thevertical pressures, we should here similarly expect to meet chieflywith reversed faults; and in each case our surmises would proveconnect. It should, however, be remarked, that the above are considerationsof the most simple case, and in practice we should meet with manyvariations which would m
. Geological magazine. at vertical pressureshave exceeded horizontal pressures, (arguing as above) we shouldhere exj)ect to meet with direct faults; but since it is certain inhighly contorted and cleaved strata, as in the English and Welshslates, that horizontal pressures have at one time far exceeded thevertical pressures, we should here similarly expect to meet chieflywith reversed faults; and in each case our surmises would proveconnect. It should, however, be remarked, that the above are considerationsof the most simple case, and in practice we should meet with manyvariations which would modify the result. First and foremostamongst these should be mentioned that the hade of the faults willseldom happen to be 45° (as in the figures), a lower hade tending toneutralize the motive power of the vertical pressures, and a higher,that of the horizontal pressures, while if the fissure be vertical, thehorizontal pressures will have no motive power at all. Still further Geol. Mag. 1877 Jiew Series DecadeJI_Vo] IV. nn •[ZI] O/. Mount SobUl- h. MiUTZt Tbenkar C ? SigaXoet Moumains. d. Mmwjt Ms^^co f. Mount Haewi^oJL Barock ^.i^nz}^ Jhaia^e-and iorphyry [ Vi Q. SigaZoet CoaJ/ield SyenjUs j ; • Oemhihen Coalfield. GEOLOGICAL PANORAMA OF THE OEMBILIEN COALFIELD, CaaJJleldHIGHLANDS OF PADANG. WEST COAST OF SUMATRA. M. Verheek—GeoJogij of Sumatra. 443 complications will ensue when the horizontal pressures are of such adirection as to produce a certain amount of lateral shift in the strataon either side of the fault, as would be the case in our illustration, ifthe square of wood were not sawn at rigid angles to its surface, butwith the saw on the slant, in which case, the pressures being applied,the two pieces of wood would no longer tend to move in the planeof the square; and it is here necessary to remark that reversedfaults resulting from the horizontal pressures accompanying cleavage,will not be exhibited on the cleavage faces of bedded slates, exceptwhere the pressures
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Keywords: ., bookauthorwoodward, bookcentury1800, bookdecade1870, bookyear1877
