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JOURNAL OF THE GEOLOGICAL SOCIETY OF DUBLIN. 
being quartz, and occasionally jasper. The result of the second fault 
is also an upcast on its west side, which again throws the boundary 
of the upper Old Red more to the north, at the distance of 1300 
feet westerly; from the second fault we find a third fault, having 
the same general direction as the others, and, like them, shifting the 
beds to the north; and still further to the west, there is again a 
fourth fault, which produces precisely the same results as the others. 
In this manner the upper Old Red thins out, as it were, on the 
north flank of Tore Mountain, and appears but as a narrow band 
as we approach Dinish Island from the east. This fourth fault 
Mr. Du Noyer believed to be a continuation of that previously de¬ 
scribed, and named the Brickeen Island fault; it is therefore one of 
considerable magnitude and importance, producing so great an up¬ 
cast on its western side as to bring to view the middle beds of the 
Old Red Sandstone in many places along the east shore of Dinish 
Island. 
The beds underlying the upper Old Red of Tore Mountain 
differ essentially from those on the opposite shore of the Tore 
Lake; there they consist of purple grits and slates, here they are 
greenish-gray grits and slates, with a few purple slates through 
them. The Tore Island boundary fault, and two others which 
occur at the Dead-cow Cliff to the west, have aided in producing a 
singular modification in certain contortions of the beds along the 
