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nesian rocks abound, which are extremelyrare on the southern. If these rocks de- ^rived their inclined posture from eleva- £tion or subsidence, why are they not foundon both sides of the chain ?

Secondary Limestone occurs very abun-dantly on the north-eastern flank of theprimitive chains in Saxony , and Bohemia ,the Alps, the Carpacks, and even in North America ; but very sparingly on the south-eastern flank of those chains.

The coal-measures on the opposite sidesof the Derbyshire limestone are dissimilar,and the shisti on the opposite sides of theOcrinian chain.

Humboldt * remarks, that the direction ofhigh chains of mountains seems to havegreat influence on the direction of strata,even at a considerable distance. Of this in-fluence which Humboldt has observed inthe Pyrenees and in Mexico Ebel b hasdiscovered numerous instances in the Alps.

5. The irregularities observed in the stra-tification of some beds seem to warrant the

* Journal de Physique, voL lxxi. p. 372.

b Ebel, vol. i. p. 220. vol. ii. p. 201. 215. and 357.

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