Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/29

 Rh sienite which I have been describing seems to be continued as far round the eastern coast as les Burons, where trap is again found. Of this part of the coast I can say nothing more particular. Those shores which are not impracticable are very difficult of access; and that which was accessible was sufficiently various to occupy more time than I was able to appropriate to its examination.



Further to the north, and on the eastern side, is the port of the Creux. This is a dry beach, in a cove formed by high cliffs of argillaceous rock, of which the faces are absolutely perpendicular in most parts, and as smooth as a wall. Being inaccessible from the land, and at the same time the only secure beach on the island, a communication was formed in 1588 by De Carterets, who excavated a tunnel through the rock; taking advantage of a loose vein which traverses it. This passage is occupied by a gate, and thus the chief landing place is rendered defensible by a very small force. The whole is strikingly picturesque and singular.

Bridges of detached rocks stretch out to sea from this point, which from the peculiar form of their outline appear to be granite.

There is a small funnel on the coast resembling the Buller of Buchan or Tol Pedn Penwith: it is called Creux terrible. I did not see it.

From hence to la Noire is an inaccessible promontory, but on the other side of it, is a steatitical vein containing asbestus, and which is probably the continuation of a vein I shall have occasion to notice on the western side of the island at Port des Moulins.



I also observed a large vein of black porphyry, of a beautiful texture, and capable of a high polish, containing distinct and large concretions of white and pale green felspar. An inaccessible vein is also here visible, of which the lower part has been washed out so as to form a cavern. The upper part which remains, shows blocks of