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On the Boundary between the Upper and Lower Cretaceous

Published online by Cambridge University Press:  01 May 2009

L. F. Spath
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Extract

The Cretaceous System of England, according to A. J. Jukes-Browne1 is “naturally divisible into two distinct and different series of strata”, namely a lower series consisting chiefly of sands and clays, and an upper series, consisting mainly of chalk. The succession on the whole is easy to unravel, and was correctly described (even before the name Cretaceous had been thought of) by Webster in his Letters, written in 1811 and published in 1816 in Sir Henry Englefield's Isle of Wight; it is almost exactly the same as we recognize it to-day. Two slight changes have been made, but they have been considered by some to be changes for the worse. Firstly, the beds to which the name“Greensand” had originally been applied by Smith and Webster2 are now called “Upper” Greensand, a term that has given rise to much confusion3; and, secondly, the “Ferruginous Sands” are now known as “Lower” Greensand, a name that was strongly condemned by workers like Fitton, Godwin-Austen, and Judd. It is on record4 that even Jukes-Browne admitted that he had long been endeavouring to do away with the awkward and misleading terms “Upper” and “Lower” Greensand ; but these names, though better not used without locality, have now become too familiar and are too useful for mapping to be abandoned entirely in favour of the more precise stage names Cenomanian, Albian, and Aptian.

Type
Articles
Information
Geological Magazine , Volume 78 , Issue 4 , August 1941 , pp. 309 - 315
Copyright
Copyright © Cambridge University Press 1941

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References

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