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LXVI. Proceedings of Learned Societies. 
GEOLOGICAL SOCIETY. 
[Continued from p. 416. } 
May 25th, 1904.—J. E. Marr, Sc.D., F.R.S., President, 
in the Chair. 
y i ‘HE following communications were read :—~ 
1. ‘ On the Occurrence of a Limestone with Upper Gault Fossils 
at Barnwell, near Cambridge.’ By William George Fearnsides, Esq., 
M.A., F.G.S. 
The section in the great Gault-pit worked by the Cambridge 
Brick Company at Barnwell is as follows :— 
Thickness in feet. 
5. Surface-soil with gravel and Chalk-Marl, disturbed ... 15 to 17 
4, Dull leaden clay, almost devoid of determinable fossils, 
3 
but with a few phosphate-nodules, ete. .................. 39 
. Compact, well-joimted, homogeneous clay, with large 
ammonites of the restratus- or Bouchardianus-type . 3 
2. Hard caleareous bed with Jnoceramus, Schlenbachia 
varicosa, and Terebratula biplicata .......ccceecceceecesees Otol 
1. Blue, well-laminated clay, with fossil-fragments and 
pale phosphate-nodules  .............esceeeeeeeees ves SG ROE 4 seen 
The limestone is variable in thickness, and is largely made up of 
comminuted shells of Jnoceramus. It occurs in a series of flattened 
lenticles, a few yards in diameter and about a foot thick. It 
contains abundant phosphate-nodules of at least three types—green, 
pale, and dark-brown in colour, Foraminifera are abundant, as also 
fragments of lamellibranchs, brachiopods, small gastropods, echinoids, 
and crustacea. A fibrous material, possibly chitin, chips of quartz, 
a little orthoclase, and glauconite are also recognized microscopically. 
The fauna is not markedly different from that of the underlying 
clay. A Jistis given which shows that this fauna has been recorded 
from the Upper Gault of Folkestone, and agrees most closely with 
that from Bed IX of Mr. Hilton Price’s paper on that locality. As 
these fossils are obtained 40 feet below the upper surface of the Gault 
seen in the section, it is clear that the whole of the Upper Gault of 
Cambridge was not used up in the making of the ‘Cambridge 
Greensand’; and this fact, together with the northward thinning 
of the Gault as it passes into the Red Chalk, necessitates a 
modification in the view commonly held as to the origin of this 
‘ Greensand’ deposit. 
2. On the Age of the Llyn-Padarn Dykes.’ By James Vincent 
Elsden, Esq., B.Sc., F.G.S. 
The paper produces evidence which seems to suggest that the 
bulk of the greenstone-dykes of this area belong to an earlier 
period of eruption than has been generally assigned to them; and 
there is proof that some of them may even be older than the 
