Geological Relations of tb * East of Ireland \ 279 
is entirely composed of trap, in massy strata, four, five, and six feet 
thick, dipping 20° toward the east of south. These rocks consist 
principally of porphyries, red, brown, grey, and green ; but trap 
conglomerate also occurs. Of this description are also the rocks in 
the larger and more southern part of Knock Rua, and so also in 
a third hill of the same range more toward the south-west, called 
Balloch-bega, at the northern foot of which limestone rock is also 
visible. 
I did not extend my researches to the southward of this quarter, 
but from the form of the country as seen from Pallis hill, I am led 
to suspect that there are one or more great beds of trap to the 
south of Knock Rua and Caherconlish. There is one hill in par- 
ticular, situated apparently about three or four miles to the south of 
this Knock Rua, which much resembles it in form. 
In this series of trap rocks, I have no where observed any of the 
zeolite family. 
§ 179. In the association of the floetz limestone of Ireland with 
trap rocks, we perceive some analogy to what is observable in Der- 
byshire, where the mountain limestone is interstratified with trap \ 
commonly with greenstone and amygdaloid, but also with basalt, of 
which last I have distinct specimens from that country ; and this 
analogy is supported in other respects. The coal rocks of Derby- 
shire rest upon the limestone and trap ; and a few miles more to the 
south of the district we have been considering, near Charleville, we 
find our limestone field bordering upon and supporting the Mun- 
ster coal tract. And, if we examine the organic remains contained 
in the two limestones, we perceive a farther coincidence ; entro- 
chites, madreporites, tubiporites; also ammonites, euomphalites, 
orthoceratites, many species of anomites, terebratulites, being found, 
abundantly, in both. And this analogy extends, in many respects* 
