586 
SECOND REPORT-1832. 
been uplifted by the granite. In the neighbourhood of the gra¬ 
nite the slate differs in composition, and becomes metalliferous; 
a connexion between the rocks which could scarcely have sub¬ 
sisted, if the granite had been injected. The composition of 
the mineral and metalliferous veins of Cornwall varies accord¬ 
ing to the nature of the rocks which they traverse : and the 
veins and the rocks are always intimately connected together 
by mineral transitions, similar to those which so frequently oc¬ 
cur between different rocks. He further remarked, that the 
phenomena of veins, commonly referred to motion, are often 
exhibited, even in hand-specimens of Carclaze granite, and of 
St. Agnes slate ; the veins being arranged in the joints of the 
laminae : and these facts appear to admit of no other explana¬ 
tion, than that the production of the veins was coeval with the 
formation of the rocks. Lastly, he begged to suggest for the 
consideration of geologists, whether the arrangement of veins, on 
the large scale, is not perfectly analogous; since the different se¬ 
ries of veins cross each other in directions corresponding with 
those of the joints or seams of the rocks, the latter having the 
same mechanical structure as the individual concretions and la¬ 
minae of which they are composed.—Professor Sedgwick, in an¬ 
swer to a question from Sir Philip Egerton, said that in certain 
cases of contorted rocks, the contorted masses are the true beds, 
the fissures being the lines of cleavage; and that these fissures 
continue parallel to fissures in the undisturbed beds.—Sir Phi¬ 
lip Egerton observed, that in the Isle of Man he had seen 
veins in grauwacke running at right angles to the lines of cleav¬ 
age, and that he had examined a vein of granite, found in sinking 
a shaft, adjoining which the slate had been broken into fragments, 
and re-cemented ; veins of felspar, and a vein of lead, here run 
parallel to the granitic vein. This vein is supposed to be a ra¬ 
mification from the main body of granite which only appears in 
one place of the island. Sir P. Egerton also described the oc¬ 
currence of a vein of copper-ore in the new red sandstone of 
Cheshire. 
Mr. Carne, explained his views on the relative age and di¬ 
rection of the veins in Cornwall; he concurred with Professor 
Sedgwick in his distinction of veins of segregation, and remark¬ 
ed that contemporaneous veins, which are sometimes metallifer¬ 
ous, terminate in length and depth ; but that metalliferous veins 
of fissure do not terminate. Mr. Carne exhibited specimens 
of tin ore from Cornwall, showing that certain varieties, which 
had formerly been found only in alluvium, have lately been dis¬ 
covered in situ in true veins. Wood tin, or fibrous oxide; toad’s- 
