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| Fig. 9.—Anticlines and Synclines. |
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| Fig. 10.—Contorted Strata. |
When strata shew many and rapid curves, they are said to be contorted. The diagram section ([fig. 10]) will best explain what is meant by this kind of structure.
46. In certain regions, the strata often dip in one and the same direction for many miles, at an angle approaching verticality, as in the following section. It might be inferred, therefore, that from A to B we had a gradually ascending series—that as we paced over the outcrop we were stepping constantly from a lower to a higher geological horizon. But, in such cases, the dip is deceptive, the same beds being repeated again and again in a series of great foldings of the strata. Such is the case over wide areas in the upland districts of the south of Scotland. The section ([fig. 11]) shews that the beds are actually inverted, the strata at × × being bent back upon strata which really overlie them.
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| Fig. 11.—Inversion of Strata. |
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| Fig. 12.—Contemporaneous Erosion. |