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PEOCEEDINGS OF THE GEOLOGICAL SOCIETT. [JunC 23, 



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/. Origin of the JBlachjoool Drifts. — Leaving the question of the 

 origin of the Postglacial deposits to those who have devoted more at- 

 tention to their character as exhibited on 

 ^ different parts of the Lancashire coast, I may 

 &i) remark that while few would doubt the 

 ^ marine-glacial origin of the Upper Boulder- 

 r5 '^* clay, and while no one can dispute the purely 

 w marine origin (with the exception of boulders 

 ^"S drifted into it by floating ice) of the middle 

 . ^ sand and gravel formation, the precise mode 

 1-^ of accumulation of the Lower Boulder-clay 

 *!'4{v,j ■"* -g appears involved in mystery. At first sight 

 i*!v 'ntfj\ S ts ^^y one might hastily conclude that it is a 

 land-glacial deposit ; but a reconsideration 

 of its varied phenomena, and a correlation 

 of this clay with what we have reason to 

 I ^ believe are equivalent deposits on the other 

 >."© side of Morecambe Bay (see sequel) and in 

 'o'^^ South Lancashire, would seem to point to 

 ^ ^ accumulation under mixed glacial and marine 

 'tf ^ conditions. Admitting that the stones and a 

 pq ° great part of the clay were furnished by 

 ^^ land-ice (in the Carnforth area the stones 



^ would appear to have been transported chiefly 

 by coast-ice ; see sequel), the sea at least 

 must have kept u}) what may be called a 

 running accompaniment to the accumulation 

 of the drift-matter, by washing out and re- 

 depositing its finer parts in the shape of 

 laminated loam. In some parts of IN'orth- 

 west Lancashire the Lower Boulder-clay may 

 be entirely a land accumulation; but it is 

 difficult to resist the belief that where this 



1 r^ formation spreads out continuously over large 

 ^ U flat areas, it must have been deposited under 

 ^"-o the surface of the sea*. It may likewise 

 ^ ^ be remarked that at Blackpool the numerous 



granitic boulders and stones, which could not 



results of the first thorough, minute, and systematic 



.- •■ ',T( investigation that has yet been made of tlae succession 



Ait#||y/ .*' > j M'^ of Postglacial deposits and their connexion with 



J\T\|Mly;\*i .Is deposits of the prehistoric and historic periods. He 



cMm .'.A! ^' '^„ has been surveying the country south and east of 



'^ £" Southport. 



^ $. * I have just learned (March 1869) that Mr. 



^ g Morton, F.G-.S., some time ago discovered sea shells 



o (>^ in Lower Boulder-clay near Liverpool, and that one 



'^ of the Geological Surveyors (whose name I am not 



S yet at liberty to publish) has made a discovery during 



p4 a short visit to Blackpool which demonstrates that 



i-* the Lower Boulder-clay there, is, at least partly, of 



^ marine origin. 



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