SUBTERRANEAN MOVEMENTS, &c. 
125 
The only other view remaining to be noticed is the opinion now 
prevalent in Cornwall, that there is no criterion of age to be derived 
from the intersections of veins ; and in fact that these can not be 
proved to be of different age from the rock. There is always more 
difficulty in demonstrating this difference in rocks which, like the 
slates of Cornwall, are more remarkable for symmetrical than strati- 
fied structure. But it can be proved even in these instances that 
most of the veins occupy fissures which are of date subsequent to 
the rock ; this granted, the relative date of veins which meet follows 
the same laws as those in other districts. 
Upon the whole we may admit the greater number of cross veins to be 
of later date than the divided veins, at least in the limestone tracts ; some 
exceptions may and probably do occur, but more and better arguments 
are required to prove it than any yet adduced. The cross courses 
in Yorkshire and Tynedale run generally about N. N. W., parallel 
to the Cross fell faults, This however may not be more than an 
accidental relation, for N. N. W. fissures are characteristic all over 
Yorkshire and frequent in the bordering counties. It is more pro- 
bable that the range of the Cross fell fault and that of the cross 
veins of the North of England are dependent on this constant struc- 
ture of rocks, which appears to be the primary phenomenon. 
In the same manner the east and west veins are coincident with 
a system of fissures in limestone, which probably guided in part the 
Tynedale fault ; the Greenliow veins appear related to E. S. E. courses, 
because the fissile structure of the subjacent slates is developed in 
that direction, and has permitted two parallel dislocations to happen 
along these divisional planes. 
Coalfield of Lonsdale , 
The history of the mountain limestone district of Yorkshire would 
be incomplete without some notice of the remarkable coalfield which 
lies in the low valley of the Greta, at the foot of Ingleborough. In 
the natural order of events its description should have followed that 
