. Flowers and their pedigrees. e question now remains, If the land once thusextended farther out to sea than at present, how farout did it extend ? or, in other words, how large asubsidence has taken place ? Here we have anexcellent hint for our guidance in the fact that Irelandmust have been united to England since the glacialepoch, because we find in Ireland a large proportionof the British plants and animals, including a con-siderable number of land mammals. Now, how muchmust we raise the general land surface of the BritishIsles in order to unite Ireland to Great Britain ?Well, a rise of le
. Flowers and their pedigrees. e question now remains, If the land once thusextended farther out to sea than at present, how farout did it extend ? or, in other words, how large asubsidence has taken place ? Here we have anexcellent hint for our guidance in the fact that Irelandmust have been united to England since the glacialepoch, because we find in Ireland a large proportionof the British plants and animals, including a con-siderable number of land mammals. Now, how muchmust we raise the general land surface of the BritishIsles in order to unite Ireland to Great Britain ?Well, a rise of less than one hundred fathoms wouldsuffice to join the whole of our islands throughoutnearly all their length, leaving only two large lakes inthe very deepest parts of the sea, where the plummetmarks a depth of a hundred and fifty fathoms. One 68 Flowers and their Pedigrees. of these two large lakes would lie between Gallowayand Ulster, and the other would fill up the hollow ofthe Minch between the Hebrides and the Isle of FRAN C E Fig. 16.—Sketch Map of Post-G!acial Britain. But the same amount of elevation would also sufficeto unite us to the Continent from Denmark to Spain,as well as to push out our whole coast-line about fifty The Romance of a Wayside Weed. 69 miles to the westward of Cape Clear. Beyond thatdistance the sea-bottom suddenly topples over from ageneral depth of a hundred fathoms to a depth of athousand fathoms or more ; which clearly shows thatthis line, curving round from Shetland to the Spanishshore of the Asturias, must mark an old and long-con-tinued prehistoric land-barrier. In other words, theBritish Isles are situated on a comparatively shallowsubmarine bank, which spreads north, south, and eastof them, but ends abruptly to the westward by asudden drop of eight or nine hundred fathoms. Ifyou were now to raise this bank a hundred fathoms inheight, you would lift its whole area above the sea-level, save only in the two hollows already noted ;but if
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectplantse, bookyear1884
