XXX1 
It is scarcely more important that the practical miner should 
acquaint himself with the several changes of character which ac- 
company a passage from the poorer to the richer parts of his lode, 
than that—when one vein has dislocated another—he should know 
whether the chances of successful search for the severed vein are . 
greatest towards the right or the left-hand* in case of horizontal 
(heave) displacement,—upward or downward + if the displacement 
be (a leap or throw) vertical ;—or towards the greater{ or the 
smaller§ angle in either case. Of 272 lodes traversed by cross- 
veins in different parts of Cornwall ||— 
57 or 0:20 of the whole number are intersected, but not (heaved) displaced ; 
135 ,, 0:50 are (heaved) displaced towards the right-hand ; 
80 bed 0:30 be) ” ” 99 ” left ” 
181 ,, 0°67 4 a BA ve <5 greater angle ; 
34 ” 0-13 ” be) 9 99 ” smaller ed 
The extent of (heave) displacement towards the right-hand averages 17°7 feet ; 
99 9 bed ” left bh) eh) 2. ” 
” ” ” ” greater angle ” 15°9 ,, 
” 99 ” 9 smaller 9? 9 16-0 ”? 
By vs », throughout the County ,, _,, IEEE). 
Nor can the enquiry whether the direction or the extent of the 
(heave) displacement depends on—the nature of the adjoining rock, 
—the composition, width, or inclination of the lode and the cross- 
vein,—or on the angle of their incidence, be unimportant. 
The intersections, unaccompanied by 
(heaves) displace- +0:26,q in slate 0:-21q of the whole; 
ment are in granite 
Ae attended by (heaves) 
displacements  to- 0:52 
wards the ~right- : 
hand in granite .. 
3 attended by (heaves) 
displacements to- | ,. : 
wards the left-hand Dees mm  UEBS ay 
in granite........ 
* “The directions of the heaves are generally expressed by right and left, 
‘« because the same expression serves on approaching them from either side; 
‘if the terms north and south be used, it must be also said whether they are 
“‘approached from the east or west.” THomas, (R.), Report, p. 22. Carne, 
Cornwall Geol: Trans: ii., p 86. 
al Pryce, Mineral: Cornub: p. 106. Carne, Cornwall Geol: Trans: ii., 
p. 86, 
+ Hawkins, Jbid, ii., p. 228. 
§ Pryce, Mineral: Cornub: Pl i, Fig. 3, 4. 
|| Henwood, Cornwall Geol: Trans: v., pp. 286-287; viii. pp. 683- 
684, 717. 
q Ibid, v., p. 296. 
