Geology of High Teesdale. 141 
possible to institute a general comparison of the subordinate 
beds; as all the minuter features are modified or changed by 
the action of local causes. 
From one end of the mountain ridge to the other, the beds 
on its eastern flank, dip to a variable point between north-east 
and south-east, and gradually pass under some deposits con- 
‘nected with a part of the great coal formation. Between the 
mountain limestone and coal formation, there is not, however, 
any precise line of demarcation; as in many instances, they 
are decidedly interlaced with each other; the beds of coal and 
carbonaceous shale appearing among the upper beds of the 
lower series. It is, in part, to this cause that we must attribute 
certain discrepancies in our best geological maps. Thus in the map 
to which I referred in a former Paper (supra, p. 25.) Mr. Winch 
extends the region of the limestone to Winston on the Tees, 
while Mr. Greenough places the demarcation near Eglestone, 
more than ten miles farther up the river. The line marked out 
by Mr. Greenough agrees better with the general features of the 
district. But on the other hand, it may be contended, that thin 
beds of limestone alternate with the sandstone and shale in the 
immediate vicinity of Winston Bridge *. 
The eastern flank of the calcareous chain is intersected by 
many transverse vallies, in which the waters of the mountain- 
torrents unite and fall down into the lower carboniferous region ; 
and from which they either find an immediate passage into the 
sea, or descend into the great plain of the new red sandstone. 
Vallies which traverse beds of the same formation, nearly in the 
* The discrepancy is not, however, so great as might appear at first sight, for 
Mr. Greenough places some of the lower beds of the Coal-measures, and some of the 
upper beds of the Lead-measures, in a separate class under the name of the Millstone 
Grit. This classification may be good for a general map of England; but no one would, 
I think, have adopted it, who had taken his type of the great carboniferous series from 
this part of the north of England. 
Transverse 
Vallies. 
