XXVill 
one of them is intersected by a metalliferous vein,* but generally 
they make their way through rockst and lodes alike and without 
interruption.t Their mean direction throughout the County is 
about 8.E.—N.W.;§ a course not materially different from that 
of one of the most distinctly developed series of joints in the 
rocks.|| The average inclination of such as maintain the general 
range is, perhaps, 80°;41 whereas of those which bear nearly 
E. and W. it scarcely exceeds 60°;** moreover—whatever rela- 
tion (if any) may subsist between their directions, and the amounts 
of their inclinations—they dip more frequently towards than from 
the granite.tt They are wider in granite than in slate; and at 
great than at small depths.{{ As the cross-veins affect the structure 
and partake the nature of the adjoining rocks, they become more 
quartzose whilst traversing the slates which abound in strings 
* Carne, Cornwall Geol: Trans: ii., p. 110. Henwood, Proceedings of 
the Geol: Society, i., p. 405.; Reports of the British Association, vi., Part ii., 
p. 74; Hdin: New Phil: Journal, xxii., p. 163. Cornwall Geol: Trans: v., 
pp. 287-289; vii., p. 183; viii., p. 685. 
+ Sir H. T. De la Beche’s Report, pp. 297-298, describes and figures a 
displacement of the granite by the great cross-course near J'reskerby; but 
neither the Ordnance Geological Map, coloured by him at the same time, 
nor Mr. Thomas’s Geological Map of the Mining District, published seven- 
teen years earlier, shows anything of the kind. 
* Pryce, Mineral: Cornub: p. 98. Berger, Geol: Trans: i., p. 165. 
Phillips, (W.), /bid, ii., p. 134. Thomas, (R.), Report, p. 21. Carne, Corn- 
wall Geol: Trans: ii., p. 108. Fox, Reports of the Royal Corn: Pol: Society, 
iv., p. 83. Dela Beche, Report, pp. 297, 303. Henwood, Cornwall Geol: 
Trans: v., p. 256; viii., p. 682. Von Cotta, Ore-Deposits, p. 417. 
§ The mean directions of cross-veins in the different districts are—in 
Saint Just.... 26° N. of E.—S. of W. | Redruth, &c... 35° S, of H.—N. of W. 
Saint Ives.... 38° 8. of E.—N. of W. | Saint Agnes .. 39° HE. of Sim W.of N. 
Marazion .... 41° S. of H.—N. of W. | Saint Austell.. 21° 8. of H.—N. of W. 
Gwinear, &.. 43° K. of Si—W. of N. | Menheniot, &c. 3°N. of H —S. of W. 
Helston ...... 21° S. of H.—N. of W. | Caradon...... 13° HK. of S.—W. of N. 
Camborne, &e. 34° EK. of S.—W. of N. | Callington.... 43° S. of H.—N. of W. 
HeEnwoop, Cornwall Geol: Trans: v., p. 279; Table 106; viii., pp. 681, 715. 
|| Lbid, v., p. 279, Tables 99, 106; viii., pp. 673, 681. 
q Ibid, v., p. 277; Viii., p. 682. 
a* Jbid, viii., p. 715; Ormerod, Quarterly Journal of the Geol: Society, 
5 O67 hq 105 PAT Tea p. Nc 
++ Henwood, Cornwall Geol: Trans: v., p. 277; vili., p. 682; Ante, 
Dale 
tt Cross-veins in granite average.............. 4-9 feet in width; 
a » Slate wh  Sopbcoseagoods BI) Gn 99 
‘is at less than 100 fms. deep average 4:0 ,, * 
” », more ,, » Sees y 6s » 
HeEnwoop, Cornwall Geol: Trans: v., p. 276, Table 104; viii., p. 685, 715. 
