Page:Transactions of the Geological Society, 1st series, vol. 1.djvu/174

 162 accompanied with remains of marine animals or other organized bodies. At Poth stream-works, about four miles from Fowey, on the shores of Trewardreth Bay, tin in the form of round pebbles is found imbedded in a bluish marl, containing the remains of marine animals at the depth of twenty feet. The tin pebbles vary in size, from a grain to that of a small egg.

At the head of Restronget Creek, not far from Falmouth, the tin-stone of Carnon is found under fifty feet of soil. I saw in the collection of Mr. John Williams, of Scorrier-house, deer's horns which were found in the same soil, and which were in no way mineralized. I was told that trunks of trees and small grains of gold had also been found in it.

The other places in Cornwall where stream tin has been met with, are at Perran Porth in the parish of Perranzabuloe, below the sea—sand in the form of large blackish grains, at Hallibesack in the parish of Wendron, at Frogmoor in the parish of Probus, at St. Dennis and St. Roach in larger, but angular fragments, at Swanpool in the parish of Ladock, often mixed with cubic galena; at St. Austle Moor, at the average depth of eighteen feet, and at St. Blazey Moor at the depth of twenty-eight feet.

The menachanite, which is found in the form of sand in the small valley of Menaccan, at a short distance from the sea, and the iserine, which is also found in the state of sand in the beds of different rivers, as well as in the neighbourhood of volcanoes, belong probably to the formation of alluvial ores.