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175 
Yorkshire Chalk was brought into harmony with the southern 
developments by Dr. Barrois with greater success than has been 
commonh^ supposed. Our own members, Lamplugh and Stather, 
have greatly aided in the work, and, finally, Dr. Rowe having 
mastered with admirable skill the coast exposures in the South, 
has given us a very full and satisfactory^ if not exhaustive, 
description of the develoj^ments of the Chalk at Flamborough. 
The Speeton Clay was zoned by Judd soon after the date 
of his Rutland Memoir, and his work has been revised in later 
years by Lamplugh, whose researches were prosecuted under 
conditions and at times that would have deterred any but the most 
hardy and determined of workers. 
Mr. Lamplugh has shown that these beds lying between the 
Kimeridge Clay and the Red Chalk constitute a marine series 
whose equivalents in the South of England are mainl}^ of fresh- 
water origin — he subdivides them into a series of zones based 
principall}^ upon the Belemnite fauna. He finds the closest 
analogies are between these beds and deposits of the same age in 
Heligoland and Russia. 
The Jurassic rocks have been diligently studied by a host 
of able men among whom must be signalised Hudleston, Blake, 
Barrow and Fox-Strangways, and, while much msiy still be done 
to complete the correlation with southern developments of the 
series and to increase our knowledge of the physical conditions 
under which they were deposited, it is unlikely that much rectifica- 
tion, if any, of the stratigraphy yWll be found necessary. 
Of the Triassic rocks little more is known than was known 
to the geologists of fifty years ago, except that a few borings, 
e.g., at Barlow and near the mouth of the Tees enable us to assign 
a definite thickness to the sandstones that form the lower member 
of the series. 
The Permian rocks have \delded a rather larger collection of 
new facts, and explorations for coal at the mouth of the Tees, 
and at Barlow, reveal the occurrence of a series of marls and marly 
sandstones above the Magnesian Limestone forming, apparently, 
a i)erfect transition from the Permian up into the Trias. The 
marls contain much gypsum and anhydrite, and in both areas 
rock salt has been discovered. 
