146

BLACKGANG.

3. A stratum of yellow sand.

4. Black shale, with thin layers of white sand.

5. White, and bright orange-coloured, sandstone.

6. Blackish ferruginous sand, mixed with shale and white sand.7- The same as No. 5.

8. Black plastic clay, mixed with thin layers of white sand.

9. Sand mixed with shale, and very strongly impregnated withiron. This last stratum is of great thickness, extending belowthe beach, and is that in which the singular hollow, describedby you, is formed, by the water-fall that comes over it.

Most of these strata are so slightly cemented, that large massesof them may be reduced to the state of sand by a slight blow:and this observation applies also to the lowest: although oxydof iron, deposited on the surface, by the water which flows overit, has formed a ferruginous crust on the outside. In this respect,it is exactly similar to that which I described as the loweststratum of Luccombe chine. More of this stratum is, however,exposed to view here, than at Luccombe, the top of it being muchhigher above the sea.

The general dip of the strata of this part of the island is a fewdegrees to the north-east. Hence, though the top of Shanklin downis not much lower than St. Catherine's, when compared with thelevel of the sea, yet the thickness of the stratum of chalk, or marl,over the sandstone on the former, is greater than that of thelatter hill.

Since the sandstone stratum is seen breaking out, on the northside of Shanklin down, at Cook’s castle, and on the south-eastside of the same hill above Dunnose, and may be traced west-wards to Gore cliff, and again on the west side of St. Catherine’s