Dr. Berger’s Account of the Isle of Man , 491 
the opposite is in contact with the slate itself. These last mentioned 
beds separate into concretions bounded by remarkably plain surfaces, 
differing from each other in form, but which do not strictly resemble 
any geometrical figure. Indeed all these beds appear to possess the 
same property to certain degree. 
DYKES IN THE KILLAS. 
Dykes, which may be termed Elvan, occur in the island. One, 
two feet broad, is seen near the Dun, rising through the chlorite 
\ 
slate, a short distance below the junction of the two streams where, 
it was stated, the granite becomes concealed. It is very variable in 
its composition, sometimes entirely quartz and chlorite. 
On ascending Slieu-ny-Clough from Foxdale, along the bed of 
the river, there occurs a streak of granite, about one foot and a half 
wide, in the mica-slate which forms the west bank. No trace of it 
is seen on the east, but it agrees in character with a bump of granite 
to which it can be traced in the middle of the stream. It appears 
to affect the fracture of the grey wacke bed above mentioned at Port 
Eshee. This consists of grains so exceedingly comminuted that we 
should scarcely be led to suspect its real nature from hand specimens* 
LIMESTONE* 
Dr. Berger has extended the limestone in his map too far to the 
north ; the boundary lies in a direct line from Cass-ny-Hawin to 
Balia Salla. That which occurs at Port-le-Murray is also separated 
from the principal bed by an intervening patch of clay-slate. 
In the immediate vicinity of the hill to the south of Athol bridge, 
the limestone encloses nodules of quartz, mentioned by Dr. Berger, 
p. 44. This may be traced thence, forming a broad band between 
Balia Hut and Balia Salla, and the appearances it presents lead me 
