which form the opposite Walls of Cross-veins. 459 
(3 b.) At Wheal Bellon one of the tin lodes heaves two 
others, but is itself also heaved by another tin lode. The in- 
redients of all four lodes are exactly alike. 
(4.) At Great Work (y), Tincroft (r), the Morvah and 
Zennor Mines (x), West Pink (w), and Dolcoath (s), the veins 
which are intersected at some levels, at other levels intersect 
the very same veins by which they had been traversed. 
In the foregoing examination of the general facts we have 
seen that every attempt has failed to restore the continuity of 
any series of veins traversed by the same cross-veins ; since 
any one motion, uniform in direction and extent, will be fol- 
lowed by greater discordances in the relative positions of the 
portions on opposite sides, than those which at present sub- 
sist. The parts, also, in contact with the opposite sides of 
the cross-veins have scarcely the faintest resemblance in con- 
tour to each other, whether the comparison be made at the 
same or at different levels. 
It has also been shown that many heaves are occasioned 
by cross-veins which first appear at considerable depths below 
the surface (5); others by cross-veins which dwindle as they 
descend, and ultimately die away (cc); and that some of the 
cross-veins seem peculiar, or confined to certain lodes, and 
do not extend to parallel ones, however near (dd); whilst 
others appear only at certain levels on a single lode, and dis- 
appear upwards, downwards, and at either end (ee). 
It has also been observed that there are breaks in the con- 
tinuity of some lodes, which are re-discovered either towards 
the right- or left-hand, although neither cross-vein nor joint 
of the rock intervenes (g g). 
The utter impossibility of re-producing continuity in all the 
lodes supposed to have been heaved by any one motion, uni- 
form both in direction and extent, at all spots on the same 
cross-vein, seems to show decisively that the heaves can 
never have originated in movement of that simple and general 
character; even making the utmost allowance for minor frac- 
tures and modifications by other local causes. 
On the other hand, the existence of heaves where so many 
conditions conclusively prove the physical impossibility of 
any general motion, the result of a great transverse fracture 
of the strata and veins, demonstrates that no such great and 
general disturbance is necessary and indispensable to their 
roduction. 
We must also admit that in some cases the cross-veins are, 
at least, as old as the ores contained in the lodes they intersect ; 
and that in one example (2.) a movement has taken place since 
the materials of the cross-vein have occupied their present po- 
