XXX 
these, and of several other metals* occur in cross-veins ; but they are 
mostly—though by no means universally—tlimited to such portions 
of them as (heave) sever neighbouring /odes in which similar metals 
and ores prevail.+ Many of our richest repositories of lead-ore have, 
however, the same directions and mineral characters as the prin- 
cipal cross-veins. Both the rocks and the /odes are intersected by 
the cross-veins, of which the quartzose portions afford almost the 
only uninterrupted natural channels for the circulation of water 
underground; whilst those parts which consist only of (/lucan) clay 
are, on the contrary, so thoroughly impermeable that they are 
often chosen as the boundaries of (Setts) mining-leases. ¢ 
The Slides have been observed, hitherto, in the police rocks 
of certain districts§ only. Their direction—which approximates, 
but is not accurately parallel to, that of the dodes—averages less 
than 20° N. of E.—S. of W.;|| but they incline differently; their 
width ranges from less than an inch to more than a foot, and 
slaty-clay is their only ingredient.4] 
* Pryce, Mineral: Cornub: pp. 48, 50. Hitchins, Phil: Trans: Ii., 
(1801), p. 159. ee (W.), Geol: Trans: ii., pp. 135, 148. Carne, Corn- 
wall Geol: Trans: ii., pp. 112-113. Fox, Reports of the Royal Corn: Pol: 
Society, iv., p. 90. De la Beche, Report, pp. 288-301, 304. Henwood, Corn- 
wall Geol: "Trans: v., pp. 267-278 ; vii., p. 183, Table i.; viii., pp. 111, 112, 
UID, Waldlo Williams, (R. H.), Repor ts of the Royal Institution of Cornwall, 
XXxix., p. 32-33. Salmon, Mining and Smelting Magazine, ii., pp. 78-83. 
Webb and Geach, Caradon and Liskeard District, pp. 18-24. Von Cotta, 
Ore-Deposits, p. 417. 
+ Berger, Geol: Trans: i., p. 166. Phillips, (W.), Ibid, i1., p. 149. 
Fox, Reports of the Royal Corn: Pol: Society, iv., p. 89. Henwood, lori: 
wall Geol: Trans: v., pp. 270-273 ; vii., p. 183. 
+ Pryce, Mineral: Cornub: p. 100. Phillips, (W.), Geol: Trans: ii., p. 
134. * Thomas, (R.), Report, p. 24. Carne, Cornwall Geol: Trans: ii., p. 115. 
Fox, Reports of the Royal Corn: Pol: Society, iv., pp. 116, 182. Bacuanth 
Bridgewater Treatise, i., p. 546. Henwood, Cornwall Geol: Trans: V., p. 258. 
§ Ibid, v., p. 283 ; Vili., p. 686. 
| Proportionate numbers of slides, coursing in different directions : 
Teyrojororankorn (PIL GS oscoocance direction 250 HK. of S.—W. of N. 
33 Oraiieiercveketeteresterete “6 N.E.—S W. 
5 Ogilhatereteras stelstaustere A s 35° N. of E.—S. of W. 
5 Op2imeatcneitisticrerets ve a 25° N. of E.—S. of W. 
8 Ogdieverercce vides s, E.—W. 
5 OP eee cueatareers r S.E.—N.W. 
a (el eadoocaa ates 3 25° HE. of S.—W. of N. 
IPC ae esl ssepsicteveveicis, austen <peisiei ees WW 19 N. of E.—S. of W. 
Henwoop, Cornwall Geol: Trans: v., p. 231. 
q Pryce, Mineral: Cornub: p. 106. Phillips, (W.), Geol: Trans: i1., 
p. 186. Williams, (J.), /bid, iv., p. 143. Thomas, Report, p. 21. Carne, 
Cornwall Geol: Trans: ii.. p. 116. Hawkins, /bid, ii., p. 232. Henwood, 
Proceedings of the Geol: Society, i., p. 405; Cornwall Geol: Trans: v., pp- 
281-283. Pike, Quarterly Journal of the Geol: Society, xxii., pp. 535-5387. 
Von Cotta, Ore-Deposits, pp. 407-408. 
