162 Dr. BergeR on the physical Structure 



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 col- 

 lection of Mr. John Williams, of Scorrler-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 Forth in the parish of Perranzabuloe, below the sea-sand 

 in the form of large blackish grains, at Hallibesack in the parish of 

 Wcndron, 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 ;f at St. Austle Moor, at 

 the average depth of eighteen feet, and at St. Blazey Moor at the 

 depth of twenty-eight feet.lj: 



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. 



* Maton's Observations on the Western Counties, vol. i. p. 152. 

 + Klaproth's Mincralogical Observations on Cornwall, p. 13. 

 X Pryce's Miner. Cornub. 



§ The iserine is a metallic sand, composed almost entirely of titanium and oxide of 

 irOnj and appears to diflfer very little from the menachanite. Dr. Thomsau has analysed 



