Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/277

 of chalk, from Newport to Cowes, is but little elevated, being indeed almost flat: in Portland, the abruptness of the cliffs on all sides is rather considerable, and as far as I have been able to judge, pretty nearly the same, somewhat less perhaps to the south.

St. Aldham's Head, the most projecting part of the peninsula of Purbeck, lies exactly on the same parallel as the southern part of the Isle of Wight, and both belong to the same formation, as does also the Isle of Portland, which projects still further to the south.

In following that part of the coast step by step, the attention is strongly drawn towards the considerable wearing away of the land and of the solid strata which is daily taking place. Between Rockenend and Blackgang Chine on the S.S.W. coast of the Isle of Wight, a land slip happened in 1799, the fragments of which cover a space of near half a mile in diameter.

As we walk along the cliffs, we see every where the surface of the soil rent by deep fissures; but a circumstance particularly remarkable is, that in this district, the decay seems to begin with the upper strata, which are gradually removed in succession. At Freshwatergate and at the Needles, those standing pyramids of chalk present us with a striking illustration of this supposed mode of decay. At the furthest extremity of High Down below the light house, there is a gap now interrupting in its upper part the continuity of that projecting tongue of chalk. Without attempting to estimate within how many years such a portion of the solid strata will be completely broken asunder, and make a Needle by itself, no one will deny that it is one step towards such an event. Conformably with this and other similar appearances, in attempting to account for the separation of the Isle of Wight from the opposite coast of Hampshire, I should be more disposed to ascribe it to the continued action of causes, the effects of which we may ascertain and even almost calculate every