458 Mr. Henwood on the Rocks and Veins 
parisons; and it will be difficult, if not impossible, to imagine 
that lines so utterly dissimilar could ever have been united and 
continuous at all parts of their descent, and fractured after 
they had become perfectly hardened. 
V. The evidence of the relative ages of veins deduced from 
their intersections. 
It has long* been strenuously maintained, that when one 
vein intersects another, the vein intersected is older than that 
which intersects it: but the district under consideration af- 
fords so many exceptions to the generality of this law, that, 
in Cornwall at least, it must be received with some limitation f. 
Whilst the mineral composition of the containing rocks re- 
mains the same, the general character of any given vein, 
whether it be a lode or a cross-vein, is usually so uniform, that 
there can be but little doubt that similar portions of the same 
vein are of the same ages, although they may be situate at some 
distance from each other, either horizontally or vertically. 
(1.) At Ting Tang and Wheal Friendship, strings of vi- 
treous copper ore and copper pyrites pass through the cross- 
veins and connect together the same ores existing in the lode 
on either side; and at East Wheal Rose lead ore is found 
under circumstances precisely similar. 
(2.) At the Consolidated Mines{, two quartz rocks, which 
fitted exactly into each other, were found at the two ends of 
a lode heaved by a flucan. The flucan, in the intermediate 
distance of 7 feet, presented a horizontal open space perfectly 
corresponding with the contour of the rocks in the ends of the 
lode. 
(3.) At Fowey Consols (g), Tincroft (7), and Duffield (p), 
the cross-veins which heave some of the lodes are themselves 
heaved by other lodes exactly similar in composition ; and, in 
short, possess all the characters common to the lodes which 
are heaved. 
(3 a.) At Polgooth (7) two lodes are heaved by one elvan- 
course, whilst one of the same lodes intersects another elvan- 
course in every respect similar to that by which it is itself in- 
tersected. 
* Dr. Borlase, Nat. Hist. of Cornwall (2nd edit., 1758), p. 152; Mr. 
Pryce, Mineral. Cornub. (1778), pp. 82-101 ; M. Werner, Theory of Mineral 
Veins (1791), p. 51; Mr. Thomas, Report (1819), p. 21; Mr. Carne, Corn- 
wall Geol. Trans. (1819), ii. p. 123; Mr. Hawkins, ibid, p. 227 ; Professor 
Phillips, Geology, Cab. Cyclop. (1839, No. cxi.), ii, p. 136 ; Mr. De la 
Beche, Report (1839), p. 353. 
+ “I think it can be shown, that the mere fact of intersection ought 
not, apart from other considerations, to be taken as evidence of the relative 
ages of veins.” Mr. R. W. Fox, Report of the Royal Cornwall Polytech. 
Soc. (1836), p. 42. 
{ My own paper, Cornwall Geol. Trans., iii. p. 329. 
