originally elevated not less than eighteen thousand feet; in height, therefore, they once rivalled the Cordilleras, and are now but poorly represented by the hills of Skidaw and Helvellyn. It were easy to show, that this estimate is still below the result that strictly follows from the Neptunian hypothesis; but it is unnecessary to proceed further, than to prove, that the principle of the degradation of mountains, is involved in that hypothesis to an excessive and improbable degree; and that the supporters of it, have either been guilty of the inconsistency of refusing to Dr Hutton the moderate use of a principle, which they themselves employ in its utmost extent, or of not having sufficiently adverted to the consequences of their own system. 157. The formation of secondary strata from the degradation of the contiguous mountains, on close examination, is subject to many other difficulties of the same kind. Mountains of secondary strata, and nearly horizontal, are found in this island of the height of three thousand feet. Such are Ingleborough, Wharnside, and perhaps some others on the west of Yorkshire. The whole chain, indeed, for secondary mountains, is of great elevation. The strata are of limestone, and of a very coarse-grained sandstone, alternating with it. No mountains can more clearly point out, that the strata of which they consist were once continued quite across the vallies which now separate them; and hence, if the materials of those strata were indeed furnished from any contiguous primitive mountains, the latter must have been, out of all proportion, higher than any mountains now in Britain.