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Show 314 ISLAND LIFE. ( PART II• narrow ridge less than 500 fathoms below the surface joins the extensive bank under 300 fathoms, on which are situated the Faroe Islands and Iceland, and which stretches across to Greenland. In the North Channel between Ireland and Scotland, and in the MAP fi llOW!NO THE SHALLOW BANK OONNEOT!NO '!'HE 11R11 1Sll I SLI::S WI'J'IT 'J'I!l; i~o 1 11 ight tint indicates n depth of less than 100 f.otihoms e gurcs show tho depth in fatho1ns ' · The narrow channel between Norway and Denmark is 2,580 feet (leep. '()N'I I :-.J F .' 'l'. !linch b~tween the outer Hebrides and Skye, are a series of ollows m the sea-bottom from 100 to 150 fathoms dee . These correspond exactly to the pojnts between the opposinpg ()[lAP. XVI.] THE BRITISH ISLES. 315 hiD'hlands where the greatest accumulations of ice would ne~essarily occur during the glacial epoch, and they may well be termed submarine lakes, of exactly the same nature as those which occur in similar positions on land. Proofs of Former Elevation-Submerged Forests.-What renders Britain particularly instructive as an example of a recent continental island is the amount of direct evidence that exists, of several distinct kinds, showing that the land has been sufficiently elevated (or the sea depressed) to unite it with the continent, -and this at a very recent period. The first class of evidence is the existence, all round our coasts, of the remains of submarine forests often extending far below the present low-water mark. Such are the submerged forests near Torquay in Devonshire and near Falmouth in Cornwall, both containing stumps of tr~es in their natural position rooted in the soil, with deposits of peat, branches, and nuts, and often with remains of insects and other land animals. These occur in very different conditions and situations, and some have been explained by changes in the height of the tide, or by pebble banks shutting out the tidal waters from estuaries; but there are numerous examples to which: such hypotheses cannot apply, and which can only be explained by an actual subsidence of the land (or rise of the sea-level) since the trees grew. We cannot give a better idea of these forests than by quoting the following account by Mr. Pengelly of a visit to one which had been exposed by a violent storm on the coast of Devonshire, at Blackpool near Dartmouth :- " We were so fortunate as to reach the beach at spring-tide low-water, and to find, admirably exposed, by far the finest example of a submerged forest which I have ever seen. It occupied a rectangular area, extending from the small river or stream at the western end of the inlet, about one furlong eastward; and from the low-water line thirty yards up the strand. The lower or seaward portion of the forest area, occupying about two-thirds of its entire breadth, consisted of a brownish drabcoloured clay, which was crowded with vegetable debris, such as small twigs, leaves, and nuts. There were also numerous prostrate trunks and branches of trees, lying partly imbedded |
