382 Mr. Henwood on the Rocks and Veins : 
with opposite inclinations are, in consequence of the elevation, 
opposed to each other on different sides of the cross-vein, at 5! 
these severed portions, when viewed in profile, will appear to 
cross each other, and at that point a simple intersection will 
again occur. Below 4', however, the elevated portion will 
be on the side opposite to that which it occupied above; in 
fact, there will be a left-hand heave below the point 6!, and a 
right-hand heave above it. 
Though a simple case, this is, however, one of very un- 
common occurrence, for I have met with but three examples* 
of heaves of the same lode by the same cross-vein which are 
in opposite directions at different levels, viz. at the United 
Mines, Wheal Robert and Wheal Providence (7, ¥, a), and 
as they form so small a proportion, it seems scarcely necessary 
to pursue this point further. ‘ 
(3.) Instead of a vertical motion we will now consider one 
on a line passing through the various flexures of the lode, and 
which shall, in fact, be coincident with its mean dip. 
Let AB (Pl. IV. fig. 5) be the level of the surface ori- 
ginally, A’ B! that to which that portion of it has been ele- 
vated ; a, 6,6, 6 the lode in the former, and a', b', 5', b' that 
in the latter, curved as it descends in both; po the direction 
of the motion. It is obvious, that as a, b, b, b, and a, b', b', 
were originally united and continuous, their configuration 
must be alike; and that, during the motion of A! B! with the 
lode contained in it, several of the sinuosities of the latter 
must have passed similar ones in the former, until finally 
from a to 6! the heave is towards the right-hand: at 4! the 
lodes cross, and there is a simple intersection only; from 0! 
to 6 the heave is towards the left-hand, and at é there is a 
second simple intersection; from 6 to 6! the heave is again to 
the right, and at )' a third simple intersection occurs; from 
b' tod there is again a right-hand heave (for at 5! the two parts 
of the veins merely stand opposite to each other, and do not 
cross) ; at } there is a fourth simple intersection, and thence 
downward there is a left-hand heave. This iteration of contra- 
dictory phenomena is thus obtained with no greater flexures, 
in a direction contrary to the general dip, than are common in 
lodes. 
But although these slight reverses often occur, a reversed 
dip for any great extent is very unusual ; and such contradic- 
tory heaves are entirely unknown in Cornwall. 
(4.) We will now see how far the results of curvilinear 
motion will agree with observation. 
* Mr. Carne describes a case of the kind at Gunnis Lake (Cornwall 
Geol. Trans. ii. p. 99), and another is said to have occurred at South 
Wheal Towan. 
