Geological Relations of the East of Ireland \ 
165 
3. Clay Slate . 
§ 51. This formation is spread over considerable tracts, both 
on the eastern and western sides of the granite chain, and I shall 
first consider the western division. 
§ 52. The Tallow hills, (see Plate 9. No. 10,) which bound 
Seechon on the north-west, consist of clay slate, greenstone, and 
greenstone porphyry, interstratified with each other, the latter 
rocks more particularly abounding in the eastern quarter. Their 
range is generally 10° north of east and south of west, with a dip 
toward the south. Rathcool hills are composed of clay slate, clay 
slate conglomerate, and greywacke slate, which alternate with each 
other, as may be observed in the quarries on the north-western 
brow of these hills. The clay slate conglomerate consists of angu- 
lar fragments of clay slate, some nearly as large as the head, with 
smaller fragments of quartz, imbedded in and cemented by clay 
slate. The greywacke slate is of similar composition, with a small 
grain and fissile structure. These rocks appear in general to pre- 
serve the same range as those of the Tallow hills, but on the 
south-eastern side they are partly contorted and inflected. In a 
ravine in this quarter, they contain beds of quartz, from eight to 
twelve inches in thickness, and these rocks range here north-east 
and south-west, and dip 55° to the south-east. 
§ 53. The chain of hills which extends to the southward, and 
which I have called the Rathcool range, is also of the same cha- 
racter. 
§ 54. The low group, west of Rathcool, which includes Wind- 
mill hill, Athgoe, Lyons, and Rusty hills, is composed of clay slate, 
greywacke, greywacke slate, and granite. The greywacke consists 
