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.

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    of the same rocks as the main land, from Avhich it is separated by a short interval. In a general view, the geological structure of Jersey may be described as that of an island, the greater part of whose high and northern tract consists of granitic rock, upon which the remainder of the island toward the south re- poses. The granite or syenite, which has a pleasing reddish tint in some places, forms the lowest rock, and upon it an argillaceous and schistose series of rocks rest in a south-western direction; while toward the north-east a con- siderable mass of hornstone and conglomerate is found running. Veins of porphyry, and par- ticularly of felspar, are also found intersecting the other strata in various places, and in a greater or less degree of decomposition, and variously tinged, green, red, and yellow. Beds of amygdaloid and green porphyry are also met with, and are quarried and employed for paving and in the construction of walls. The singular rock, conglomerate or pudding-stone, is found near Rozel Bay. It consists of rounded frag- ments of rock, cemented into a hard mass by a medium apparently of an argillaceous or clayey nature, with some traces of iron. To those who are not conversant with the formation of: mineral substances, few objects can be more surprising and perplexing than the large masses ■