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THE 



AMERICAN JOURNAL OF SCIENCE 



[THIRD SERIES.] 



Aet. I. — Theory of an Interglacial Submergence in England ; 

 by G. Frederick Wright. 



Up to a very recent date English geologists were very gen- 

 erally agreed that the British Isles have been visited by at 

 least two distinct glacial epochs since Tertiary times, and that 

 during the supposed interglacial period there was a subsidence 

 in the northern part of England, amounting to from 1,400 to 

 2,000 feet. The evidence most relied upon in proof of this 

 theory is the occurrence of interglacial stratified beds of sand 

 and gravel containing sea shells at Moel Tryfaen, near Mount 

 Snowdon, about 1,400 feet above sea-level, and at Macclesfield, 

 near Manchester, about '1,200 feet above the sea. At other 

 places, also, similar interstra titled beds occur at lower levels ; 

 as at Wellington, in Shropshire, about 500 feet above tide ; 

 upon the east coast, near Flamborough Head, from 300 to 400 

 feet ; and throughout Holderness, at lower levels. North of 

 Flamborough, also, the glacial deposits pretty continuously 

 show a threefold division, consisting of two strata of till sepa- 

 rated by stratified material, but the deposits here nowhere rise 

 more than 400 or 500 feet above the sea. 



But in view of accumulating facts concerning the stratifica- 

 tion that takes place about the margin of a great glacier whose 

 front is subject to temporary oscillations, interglacial stratified 

 beds cease in themselves to be evidence either of absolutely 

 distinct glacial epochs or of subsidence. The occurrence of 

 unbroken salt-water shells in some of these deposits appears 

 more nearly like positive proof. It would seem, however, 

 that even this must now be regarded, not only as questionable 



Am. Jour. Sci. — Third Series, Vol. XLIII, No. 253. — January, 1892. 

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