Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/415

From Wikisource
Jump to navigation Jump to search
This page has been proofread, but needs to be validated.

seem to direct its course. In some places these approach very near together, in others they widen, and leave a greater expanse of plain. The whole of these levels from within half a mile of St. Austle to the sea having been found rich in deposits of tin, have at various times been turned over, and great quantities of ore have thus been obtained: they are all at this time enclosed and cultivated. At the mouth of the river the shore is flat on both sides to some distance; at half a mile to the east begin the high cliffs that extend to Black Bear point.

The Upper Pentowan work lies about one mile north of the beginning of the sea-beach, and about one mile and a quarter north of the sea, the valley being there about half a mile wide. The following is the section of the Strata which I observed in the Upper Pentowan Stream Work.

The following is the section of the Strata which I observed in the Upper Pentowan Steam Work.
Depth from
Feet Feet
Stratum 1. Soil with trees growing thereon 3 3
2. Deposit of mud mixed with small gravel, waving thus 20 23
3. Small grained spar and killas 3 26
4. Growan (or decomposed granite), spar, killas, &c. similar to those which are now found on Hensbarrow and other neighbouring Halls 5 31
5. Gravel, at the bottom of which arc oak trees and branches, of great size 5 36
6. Tin ground 5 41
7. Clay, in which were the roots of a vast oak tree, which seemed to remain in the very position in which it grew. I was told that the trunk had been cut away for fire-wood, and that various trees had been found. Three feet above this level and at no great distance from the root was the end of a branch of oak of great size projecting from the wall of the work. The part visible was about 4 feet long and 3 feet in diameter. It is not improbable that at a greater depth a second mineral deposit may be found, as has been known to occur elsewhere under a bed of clay.