Rambles among the Channel Islands / by a Naturalist.

Date:
[1855?]
Catalogue details

Licence: Public Domain Mark

Credit: Rambles among the Channel Islands / by a Naturalist. Source: Wellcome Collection.

    140/402 (page 128)
    parts of the island are composed chiefly of deposits of schistose and argillaceous rocks. On the eastern and north-eastern coasts large veins of trap and greenstone make their appear- ance. The most interesting part of the geology of this island is at the Port du Moulin. The deseent to this place is extremely wild and picturesque, leading through a narrow pass of tall rocks down to the sea. Detached masses of rock surrounded by the sea, and relieved by the broad cliffs which bound it, constitute the peculiar feature of this port. The stratification of the rocks is here remarkably horizontal They appear to be composed of a micaceous schist, and are occasionally intersected by veins of quartz. The rock in many places breaks ^ into pieces well adapted for square masonry, to • which purpose it is applied by the islanders. . Near this spot is found the celebrated lapis - ollaris or potstone, and in the land lying above ’ the cliffs. This stone is singular in consequence /1 of its properties of infusibility, softness, andl tenacity. It is capable of being turned and i cut in a lathe, and has been used for the pim- - poses of domestic life from time immemorial It is mentioned by Pliny as applicable to thei formation of vessels of various kinds. From its use in this way its present name potstone is * derived. The islanders of Sark avail them-