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ALUM BAY.

cliffs of Alum bay (PI. XXIII. and XXIV.) just in the samemanner as the calcareous rock in Whitecliff bay; and they cor-respond also, in the nature of the substance, and the fossils whichthey contain.

These points of agreement are remarkable ; and determinethe causes of the curvature of the strata, and the circumstancesunder which they were formed, to have been the same, in bothplaces. They also point out, in a satisfactory manner, the con-tinuity of these strata ; and shew, that the clay cliffs of Whitecliffbay and Alum bay are the sections of the two ends of a long lineof vertical strata, which accompany the chalk and sandstone, fromthe east to the west end of the island. It is true, that the clayin the first of these bays is not so much striped with variouscolours, being chiefly a yellowish clay mixed with sand of thesame colour; but the bed immediately adjoining the chalk is ofthe same dark red colour as the corresponding bed at Alum bay.

I have no doubt, that the shelly calcareous rock extends overgreat part of the north side of the island; since I found the cliffsround the bays of lotland and Colwell composed of it, and Iln.ve already mentioned that it occurs also at Gurnet bay, andWhitecliff bay.

The clifls in Colwell bay (PI. XVII. No. 2.) are, like those atthe bottom of Sandown bay, formed by the section of a valley;the strata on each side of which dip in a contrary direction, risingtowards the middle of the valley.

From Colwell bay, I procured a small fishing boat to take meout to the Needles. These insulated masses of chalk, which fromthe island appear much less striking, proved, on approachingthem, to be rocks of great magnitude. ,