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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    form. The stone is of a close and small grain, and is extremely valuable for all purposes where great solidity and important powers of resisting wear and weather are required. It does not, however, appear to resist these destructive forces as much as the granite of Herm and Guernsey, which is due to a slight variation in the pro- portions of its chemical constituents. From the fact already stated of the structure of these islands consisting essentially of granitic rocks, it is very interesting to inquire into the phenomena which have led to the production of a friable and fertile soil on the surface of such hard and resisting materials. And many places exist in which this process of the formation of the soil can be traced even at the present day. In order to render this subject clearly intelligible, it may be just necessary to remind the reader that in the valleys and on the plains of England the soil is very generally derived from the waste of some distant mountainous part, and has been deposited by Avater. Such soil is called alluvial. It lies just beneath a thin stratum composed of vegetable matters in a state of decay, and it consists of sand, gravel, stones, and fine sediment or mud, all of them the products of elemental disintegration of elevated rocks or mountainous districts in