Anniversary Addyess to the Royal Geological Society. 201 
rocks was most natural. The tremendous horizontal compres- 
sion, in a nearly N. and 8. direction, to which those rocks have 
been subjected, has produced in them a slaty cleavage which 
makes them resemble very much older rocks; and then the vio- 
lent nearly E. and W. folds into which they have been thrown, 
doubtless by the same compressing force, combined with the fact 
that the outlines of the Carboniferous Slate areas are parallel with 
those folds, make it very difficult to know, without well dis- 
played contacts, whether those South Cork rocks lie above or 
below those to the north of them ; their stratigraphical relations, 
being thus rendered obscure, do not obviously correct the decep- 
tive effect of their petrological character. The discovery of 
fossils in them set the matter right. The addition of the Car- 
boniferous Slate (just above the Yellow Sandstone) completed 
Griffith’s seven-fold division of the Carboniferous System, on 
which he laid much stress. In this map the small clay-slate 
district on the N. E. side of Pomeroy, which we have mentioned 
as being left blank, was now coloured as Silurian; and this was the 
only patch of Silurian colour on this map. But Griffith knew of 
the existence of Silurian fossils at Ferriter’s Cove and Dunquin, 
near the end of the Dingle Promontory, and also at Knockmahon, 
on the coast of county Waterford. He believed that the base of 
Waterford, Cork, and Kerry is Silurian ; but the country was not 
then sufficiently examined. He thought that the Silurian might 
be only an upper member of the Greywacke, rather than a dis- 
tinct series. He expected that the greater part of the schistose 
rocks of Kerry and Cork, coloured on the map as Greywacke 
Slate, would prove to be Silurian, except a band of black slates 
in the Dingle Promontory, and running 8. W. from Caherconree; 
these last rocks are the lowest. This last map was presented to 
the Geological Society of London, on May 22, with a paper, and 
to the Geological Society of Dublin, on June 13, also with a 
paper. 
In June, 1840, only fifteen months after the last-mentioned 
edition had become accessible to the public, a new issue appeared 
which was exhibited to the British Association, at Manchester, 
in August of that year. In the short time mentioned changes 
had been made in the map in no less than forty places. Portrane 
and Lambay, county Dublin, are now made Silurian. Griffith knew 
