488 
Mr. He ns low’s Supplementary Observations to 
mica-slate and clay-slate. On Slieu-ny-Carnaane the appearance 
is similar, and as Dr. Berger notices the occurrence of blocks of 
mica-slate on this mountain, he probably considered the rock of 
which it is composed to be of that nature. 
MICA-SLATE. 
Two distinct varieties of this are met with on Slieu-ny-Clough. 
The first occurs in laminae about an inch in thickness, where the 
Foxdale river bends to the north after leaving the Castle-town road. 
The surfaces are richly coated with mica, giving the specimen a 
brilliant appearance when detached from the bed. It is traversed 
by veins of quartz and schorl, sometimes crystallized in alternate 
bands. 
The other variety is met with in two or three detached places 
lower down the stream. The rock has a greyish aspect, and 
consists of fine grains of quartz and mica intimately mixed with 
small crystals of schorl. Layers, one or two inches thick, of 
granular quartz, sometimes lie between contiguous laminae, and 
inclose small reddish-brown garnets. Other layers have larger 
crystals embedded of a liver-brown colour. Although the bed of 
the river is sunk through this to the depth of ten or twelve feet, 
and we can trace both it and the granite along different portions of 
its bottom, the actual contact is no where visible, but is concealed 
by broken masses and rubbish. 
CLAY-SLATE. 
Dr. Berger divides this into clay-slate and grey wacke- slate, and 
the latter does in fact appear to exist, though the gradation between 
it and the former is so insensible that it is impossible to draw the 
line of separation, and I have preferred designating the whole tract 
