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“ are often screened by two chains of moun-“ tains, the escarpments of which face one“ another.”

At the Dent de Vaulion, the beds dip ra-pidly to the north; in the opposite valleyto the south. At Besan<pon, the beds oneach side the valley of the Doux, are sodisposed as if they still wanted to leanagainst each other. The strata of the Northand South Downs dip opposite ways. Dor­ setshire and the Isle of Wight furnish per-haps more striking examples of similarityin the posture of strata, their posture beingvery uncommon.

Between Fast Castle * and Eyemouth inBerwickshire, may be seen segments of cir-cles in the convoluted strata, the remainingpart of the circles having been apparentlycarried away by the cause, whatever it mayhave been, which produced the indentationsof the coast.

It is obvious, that correspondence of dipat two points can afford no presumptionthat the rocks which exhibit it have been• Trans, of R. Soc. Edin. voL vii. p. 81 .