162 Mr, Griffith, on the Order of Succession of the Older 
which I think it incumbent on me shortly to reply to ; and I 
hope to be able to show that my map is correct, and that 
Mr. Hamilton is incorrect in every case in which he has 
thrown a doubt on its accuracy. 
The main points of difference between Mr. Hamilton and 
myself are; 1st, he is opinion, that in the county of Kerry, 
south of Castlemaine Bay and the lower Lake of Killarney, 
the old red sandstone overlies unconformahly those schistose 
rocks which in my map are comprehended under the general 
name of transition, and which include the Silurian system 
and the older or Cambrian slate'*. 
2nd, That the old red sandstone strata of the Gap of 
Dunloe extend uninterruptedly in a southern direction from 
the gap to the summit of MacGillacuddy’s Reeks, from which 
point they dip to the south, and are succeeded conformably 
by a new series of rocks which Mr. Hamilton considers to 
belong to the Devonian system. 
3rd, That the band of yellow sandstone shown on the 
geological map as underlying the carboniferous limestone in 
the valley of the River Rough ty at Ken mare, does not exist 
there. 
In illustration of these views Mr. Hamilton has given two 
sections, the first of which extends from the gap of Dunloe 
in a south-eastern direction across Toomies and Glena 
Mountain to the middle or Turk Lake of Killarney, and thence 
over Turk and Mangerton Mountains to the valley of Ken- 
mare ; the second is a representation of Mr. Hamilton’s view 
of the strata as they appear on the west side of the gap of 
Dunloe. 
In both of these sections Mr. Hamilton has represented 
the old red sandstone as resting unconformahly on the older 
schistose rocks, which he calls “ Cambrian but I state with- 
out fear of contradiction that his section and statements are 
incorrect in this respect, and that in the locality in ques- 
tion the old red sandstone has been deposited conformably 
on the older slate, and in a descending order graduates im- 
perceptibly into that rock. This is also the opinion of Mr. 
Weaver, who considers the whole to belong to the transition 
series; and Capt. Portlock, in his presidential address^ to the 
Geological Society of Dublin, appears to entertain the same 
opinion. 
In the first volume of the Journal of the Geological Society 
of Dublin, page 285, Mr. Hamilton describes the old red 
sandstone as forming ‘‘ an anticlinal axis on the summit of 
* See note appended to the large Geological Map of Ireland. 
