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Geological Relations of the East of Ireland . 
the latter In passing into the former gradually acquire a vertical 
position, and at length assume an opposite inclination ? The 
gradual change of position seems not improbable, when we consider 
that both rocks contain similar beds of trap, and that we have already 
seen the mica slate in a nearly horizontal position, inclined to the 
horizon under an angle of 45°, then of 52°, and lastly of 75°. I am 
the more inclined to this last opinion, because I have frequently re- 
marked slaty rocks forming a curve line in their outgoings, which 
pursued in depth presented a directly opposite dip. It is an occur- 
rence by no means uncommon in nature. And in the remainder of 
our tract, we shall observe the mica slate dipping in general only 
toward the east or south. 
§ 44. Seechon is bounded to the north-west by the Tallow hills, 
and these by the Rathcool hills, and a lower range composed of 
Windmill hill, Athgoe, &c. extending in the same direction. But 
south-west of Rathcool hill is a long chain, which, for distinc- 
tion sake I shall call the Rathcool range ; (see Plates 6. No. 2. and 
9. No. 10.) It pursues a course west of Blessington, crosses 
the LifFey, and finds a termination to the southward in the vicinity 
of Tinoran hill ; but is flanked on the western side by lower ridges 
and offsets, which pass to the west of Kilcullen and within three 
miles of Athy, and terminate near Castle Dermot. This tract is 
more particularly composed of clay slate and grey wacke, while to 
the eastward of this range of hills, and to the southward of Seechon 
southern arm, the mica slate forms in its junction with granite a 
varied and interrupted line. The Aghfarrel stream, the Liffey and 
King’s rivers, break through these rocks ; and thus detached por- 
tions of mica slate, in connection with granite, are visible at Golden 
hill and Blackmoor hill. To the south of the confluence of the 
King’s river with the Liffey, the line is more continuous, passing 
