30 CORNISH POST-TERTIARY GEOLOGY. 



Mr. Henwood gives a section of Carnon Works,' evidently at some 

 distance from the above, for a bed containing moss, leaves, nuts, 

 wood, oyster shells, animal remains, chiefly cervine, and human 

 skulls ; 18 inches thick ; rests on the tin ground, and, when traced 

 seaward, gives place to silt, the lowermost bed of the overlying 53 

 feet of sand, mud, silt and shells. 



De la Beche,^ commenting on these sections, says that the name 

 Carnon applies to a long line of works down the valley, and that 

 the shells in both sections correspond to species now living in the 

 Falmouth Estuary. 



At Perranwell, an open work, moi-e than 50 years ago, showed : ' 



1. Angular gravel, sand and silt, -witli worn masses of granite and 



slate, in thin beds ; deer remains were found at a considerable 



depth, and still deeper oyster shells 12ft. to 15ft. 



2. Fine silt, mixed with oyster shells, leaves, nuts, branches of 



trees, and very rarely wing cases of beetles 6in.tolft. 6iu. 



3. Tin ground, small rounded tin stones, angular and subangular 



blocks of schorl rock, granite, quartz, quartzose slate, and 



other vein stones. On shelf of clay slate 2ft. to 3ft. 



In Gwennap,* toward the middle of the vale, half-way from 

 Tarnon Dean (?Tannerdane on the map) to the Arsenic Manufactory, 

 large rough angular masses of quartz, two or three tons in weight, 

 rested on a bed of silt, shells, and vegetable matter, at 16 feet below 

 the surface ; beneath this, at about 22 feet below high-, and 4 or 5 

 feet below low-watermark, an entire human skeleton was discovered 

 within the compass of the layer of animal, vegetable, and mineral 

 substances. 



Cober Valley to North of the Loo Pool. 

 Mr. J. Eogers ^ says that in one part of the Cober Valley, 28 feet 

 from the surface and directly superimposed on the tin ground, a 

 vegetable stratum, containing leaves and trunks of trees, also hazel 

 nuts, was met with, there being no indications of vegetable growth 

 in the overlying deposits. At Wheal Cober no indications of marine 

 deposits were found on the Killas ; nor at Helston Gas Works, where 

 an excavation was made to a depth of 21 feet, or 7 feet below high- 

 water mark. 



1 Journ. Eoy. Instit. Corn. vol. iv. 



* Eeport on Geol. of Corn, and Devon, p. 404. 



3 Ilenwood, Journ. Roy. Instit. Corn. vol. iv. * Jbicl. p. 206. 



^ Trans. Roy. Geol. Soc. Corn. vol. vii, p. 352. 



