259 
Geological Relations of the East of Ireland . 
a considerable way, till it is covered by a bed of yellowish granular 
magnesian limestone, abounding in cavities, which &re filled with 
masses of white calcareous spar, from the size of the fist to that of 
the head, nearly. The bed of magnesian limestone appears in such 
parts as are unbroken to be eight feet thick ; it is subdivided into 
strata, which are sometimes traversed by small veins of brownspar; 
and upon these strata reposes a bed of bluish grey limestone. 
More to the south, we find the bluish grey, interstratified with the 
magnesian limestone, resting in regular conformable position, upon 
a coarse clay slate conglomerate, all dipping from 10° to 15° toward 
the north-e.ast. The conglomerate forms a bed, between two and 
three fathoms thick, divided into massy strata from three feet to 
four and a half in thickness, and cropping out to the south-west. 
It consists of a base of perfect clay slate, in which are closely 
crowded together rounded and angular fragments of fine grained 
greywacke, which is the predominating ingredient of greywacke 
slate, quartz, and a few of limestone ; those of the fine grained 
greywacke being perfectly similar to that of Portrane, Skerries, and 
the islands adjacent. The fragments are of all dimensions, some- 
times appearing as complete boulders twice or thrice the size of the 
head. The whole rock is very firm and tenacious, and obviously 
compounded of the ruins of a transition country ; and it constitutes 
a member of the floetz class, hitherto I believe unnoticed ; (see note 
to § 54.) 
To the south-westward, we observe beneath and parallel to the 
clay slate conglomerate, beds of bluish grey limestone, interstratified 
with reddish coloured limestone conglomerate, which abound in 
pebbles, angular fragments, and grains of quartz, and much re- 
sembles a sandstone. The bluish grey limestone covers clay slate, 
which is here denuded for about a square perch; (§132.) It is 
2 K 2 
