£00 Mr. Weaver on the 
upper part of their course wholly through the limestone country ; 
whereas that of the Slaney, on the other hand, touches in no part 
of its direction upon limestone rock. 
It is worthy of observation, that many of these deposits of lime- 
stone pebble, gravel, and marl are situated at distances from two to 
ten miles from the nearest part of the continuous calcareous tract ; 
and at an elevation reaching to 200, 300, and 400 feet higher than 
the existing surface of the limestone rock itself ; as, for instance, in 
the glen of lmale, and in the upper part of the Aghfarrel stream, the 
Liffey and King’s rivers. The occurrence of debris of red sand- 
stone conglomerate at an elevation considerably higher than the 
actual fixed position of this rock, is an analogous case, to which I 
have already adverted in the preceding pages (§ 136). 
§ 210. If we examine the borders of the mountain chains on 
the west and the south, we observe similar relations ; and in the 
vallies which find their outlets in the limestone plain, calcareous 
debris may be remarked intermingled with those of the mountain- 
ous tract, in some cases at the distance of two or three miles from 
the plain itself, and considerably elevated above it, while higher up 
they disappear altogether. I have already made a similar ob- 
servation in the interior of the Killenaule coal district (§ 199); and 
hence, it is evident that the cause which produced these phenomena 
was posterior to the formation of all these rocks ; since we find the 
debris of limestone not only resting high up, on the borders of older 
tracts, but also intermingled with the debris of the newer, and cover- 
ing in part the more elevated surface of the latter. 
§ 211. The limestone field itself abounds in rolled calcareous 
masses, pebbles, gravel, sand, and marl, often raised into hillocks or 
long extended ridges; which seem to owe their form to the action 
