THE 
QUARTERLY JOURNAL 
OF 
THH GEOLOGICAL SOCIETY OF LONDON, 
PROCEEDINGS 
OF 
THE GEOLOGICAL SOCIETY. 
June 22, 1870. 
Horace Pearce, Esq., 21 Hogley Road, Stourbridge, and Samuel 
Spruce, Esq., of Tamworth, were elected Fellows of the Society. 
The following communications were read :— 
1. Notes on the Lower portion of the GREEN States and PorpHyRries 
of the Laxe-pistrict between Utinswater and Keswick. By 
Henry Atteyne Nicwotson, M.D., D.Sc., M.A., F.R.S.E., F.G.S., 
&e., Lecturer on Natural History in the Medical School of Edin- 
burgh. 
Overtyine the Skiddaw slates of the Lake-district and underlying 
the Coniston limestone is a great series of rocks which are mostly of 
igneous origin, and were originally named by Prof. Sedgwick the 
‘Green Slates and Porphyries.” These rocks consist essentially of stra- 
tified felspathic ashes associated with sheets of contemporaneous trap. 
The ash-beds are mostly cleaved, and they constitute the well-known . 
“‘ green slates’ of Cumberland and Westmoreland, whilst the traps 
are often porphyritic. The origin, therefore, of the name proposed 
by Prof. Sedgwick is obvious ; but there are many reasons why some 
local name would be preferable. Near the summit of the group is a 
band containing Caradoc fossils, so that the age of this portion of the 
series is unequivocal ; but no organic remains have ever been detected 
as yet in the lower portion of the green slates, so that the exact age of 
this is somewhat uncertain. The entire series of the green slates and 
porphyries is exhibited over a very extensive superficial area, com- 
prising the central portion of the Lake-district proper, and extending 
about twenty-five miles along the strike, from E.N.E. to W.S.W., 
and about thirteen miles in the direction of the dip, from N.N.W. 
to 8.S.E. So much repetition, however, takes place, in consequence 
of folding and of faults, that it is very questionable if the entire 
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