74 SEVENTH REPORT—1837. 
On some Intersections of Veins in the Mines of Doleoath and Huel 
Prudence, in Cornwall, and on their bearing on the Theory of the 
Mechanical Origin of their (“heaves”*) Dislocations. By W. J. 
Henwoop, F#.G.S., Secretary and Curator of the Royal Geological 
Society of Cornwall, H. M. Assay Master of Tin in the Duchy of 
Cornwall. 
The object of this paper was to show, that the theory of mechanical 
disturbance, by which it was contended that mineral veins were heaved 
or dislocated in consequence of the upheaving or movement of the 
strata, or of the forcible intrusion of igneous rocks, in a state of fusion, 
intersecting and shifting pre-existing veins,—would not explain the 
phenomena as displayed in the mines of Cornwall, and is opposed 
to the experience of practical miners. To support this objection, Mr. 
Henwood adduced two examples, one from the Dolcoath Mine in the 
parish of Camborne, in which three /odes, the first being E. and W., 
and dipping 65° North; the second bearing 30° N. of W., and dip- 
ping 80° North; the third bearing 15° N. of W., and dipping 70° 
North; and, further, an Elvan course, bearing 20° S. of W., and dip- 
ping 34° N., are all traversed by a cross course bearing N. and S., and 
dipping 87° W., the result of the intersection being a very unequal 
heaving of the lodes. The first of these (or Entral Jode) has shifted 
the cross course 9 feet to the left, and is itself undisturbed. The 
second lode is heaved by the cross course 12 feet to the right. The 
third lode is heaved 30 feet to the right; and although the west portion 
of that dode is actually in the Elvan course, that course is neither 
heaved by the eross course, nor by either of the dodes. In the 
second case, or that of Huel Prudence, parish of St. Agnes, an Elvan 
course bearing E. and W., and dipping 45° N., a ode bearing 5°S. of W., 
and dipping 70° S., and another dode bearing 10° S. of W., and dipping 
68° N., are intersected by a cross course bearing 12° W. of S., and dipping 
80° E., the result being, that the Elvan course is heaved 42 feet to the 
right, the first Jode is heaved 30 feet to the right, the second (ode is 
heaved 9 feet to the right. Mr. Henwood asks, how can such varied 
effects be attributed to any one simple vertical movement or disturb- 
ance? and, more particularly, how can the heaving of two dodes both 
to the right, although they dip in opposite directions, be thus accounted 
for; since, on such a theory, it would appear that one ought to have 
been heaved to the right, and the other to the left? 
Mr. Henwood, having thus stated his objections to the received 
theory of mechanical disturbance, further observed, that he believed 
no one doubted that the tin veins at Carclaize, and the copper veins 
at Huel Music, were the result of segregation, and contemporaneous 
with the contiguous rocks ; but as these little dodes exhibited, on a small 
scale, all the characters displayed by the large lodes on a great scale, 
he did not see that any unexceptionable distinction could be drawn _ 
between them. 
* When a lode is not continuous on opposite sides of a cross course, it is (in Corn- 
wall) said to be heaved. 
