Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/30

 18 stone lying transversely and resembling masonry. I supposed it to be a vein of columnar trap similar to that I noticed at Paregorois. From Experquerie to Port des Moulins I could not examine the coast.



The descent into Port des Moulins is through a narrow pass of wild rocks, and the scenery of it is of the most picturesque class. Detached masses of rock surrounded by the sea, and relieved by the broad cliffs which bound it, constitute its peculiar feature. The whole of these rocks are of grauwacké schist and grauwacké. The strata are nearly horizontal, and are occasionally intersected by veins of quartz, as is common elsewhere. It is no where of a foliated fracture producing roofing slate, but in many places breaks into pieces well adapted for square masonry. In some places where it lies near to granite it seems to undergo an alteration of texture, and to become more siliceous. It is intersected in one or two places by wide and perpendicular veins of the magnesia class of stones; and where it is in contact with those veins, it appears to pass into schistose talc, and indurated steatite.

The veins I have mentioned contain various kinds of steatite, often so contaminated with iron and clay, and so indurated, as to be difficultly distinguished from the argillaceous tribe.

Talc, talcaceous schist, and asbestus, are found in the same veins; and with the asbestus are slender veins of Argentine spar.

Lapis ollaris is also found there, as well as in the land lying above the cliffs, from which I guess that this vein extends across the island. It is applied by the natives to economical uses.

A very large wall of a redish granite, the end of a vein from which the schistose strata have been washed, stands far out on the shore, forming a natural arch. Where the arch is formed, a softer crow fissure seems to have existed from which the looser materials