Stratified Hocks near Killarney and Dublin, 11 S 
I shall next very sliortly allude to another point brought 
forward by Mr. Hamilton in his paper. In speaking of the 
district coloured old red sandstone on my large geological 
map which occupies extensive tracts in the counties ofWater- 
ford and Cork, he observes, “ As to classification, it appears 
to me that Mr. Griffith has thrown together two rocks which 
are very distinct, namely, 1st, The old red sandstone and its 
conglomerates ; 2ndly, Compact arenaceous rocks, agreeing in 
geological position with the upper part of the Devonian series, 
as described by Professor Sedgwick and Mr. Murchison.” 
It appears to me that Mr. Hamilton is mistaken in separa- 
ting the old red sandstone from the Devonian system, as Pro- 
fessor Sedgwick and Mr. Murchison include the whole series 
under the general term Devonian : consequently, whether we 
apply the term Devonian, or old red sandstone, to the system, 
no advantage could be derived from its arbitrary subdivision. 
I freely admit that doubts may be entertained as to whether 
the yellow sandstone and carboniferous slate, considered by 
me to belong to the lowest portion of the carboniferous sy- 
stem, should not be placed at the top of the old red sand- 
stone or Devonian system. This however is not a question 
of position, but of fossils ; and as far as my present informa- 
tion extends, I still feel inclined to adhere to my original view, 
founded on the fact, that in ascending in the old red sand- 
stone series the first alteration observed is a change from 
red and yellowish green clay slate, to yellow quartzose sand- 
stone passing into light gray, which contains in abundance 
the peculiar variety of calamite already mentioned. Below 
this sandstone no fossil remains have been discovered ; above 
it they occur in abundance, and the upper beds which alter- 
nate with gray clay slate and limestone contain fossils which 
undoubtedly belong to the carboniferous limestone, though 
doubts may be entertained respecting a few which occur to- 
w\ards the bottom of the series. 
Should it appear on a more careful and extended examina- 
tion that some of the fossils of these lower beds are similar to 
those which occur in the upper part of the Devonian system, 
difficulties will still arise as to where in a graduating series 
the line should be drawn separating the Devonian from the 
carboniferous system ; and as far as Ireland is concerned, I 
think I have adopted that which appears to be least liable to 
objection ; but even on this point 1 am open to conviction. 
In the mean time the fact to dwell upon is, that the mineral 
succession which I have pointed out beneath the carboniferous 
limestone of Ireland, is similar to that described in North De- 
von by Professor Sedgwick and Mr. Murchison. 
In the conclusion of his paper Mr. Hamilton observes. 
