W. A. E. Ussher — Pleistocene Geology of Cornwall. 257 



7. Moss, hazel nuts, sticks, on pebbles of killas, growan, etc. 3-49| 



8. Rough tin ground, stones light and poor 2-5l| 



9. Eough tin ground, rich stones with quartz pebbles and 



yellow ferruginous clay. Killas at about low- water mark 354^ 



B. {op. cit.) Section of Upper Pentuan works, 1 mile N. from the 

 beach, where the valley is half a mile wide. 



1. Soil with trees growing on it 3ft. 3in. 



2. Mud with gravel seams resembling false bedding 21ft. llin. 



3 and 4. Spar and killas upon growan, spar, and killas ... 12ft. 9in. 



5. Gravel, with trees and branches of oak of great size at the 



bottom 8ft. Oin. 



6. Tin ground 8ft. 5in. 



7. Clay, in which were found the roots of a vast oak, and a 



branch 4 feet long and 3 inches in diameter, projecting 

 from the wall of the work. A second mineral deposit 

 may occur below this. 



E. Mr. Smith also gives a section of Pentowan work (either a 

 place near Pentuan, or a misprint) in 1807. 



Sandy clay, stones, gravel , — 9ft. Oin. 



Peat with roots and leaves 7ft. Oin. 



Sand with branches and trunks of trees 8ft. Oin. 



Finer sand, with shells, bones, horns, vertebra of a whale, 



human skulls 12ft. Oin. 



Coarse gravel 2ft. Oin. 



Close sand with clay, becoming peaty near the base 12ft. Oin. 



Loose stones and grave], 1 foot thick, resting on tin ground. 



Falmouth district. 



F. Tregoney Stream Work in 1807, given by Mr. Smith (op. cit.). 



1. Granitic gravel with layers of sand lift. 6in. 



2. Black mud with shells (a cow's horn and horns of stags) loft. Oin. 



3. Tin ground averaging 2ft. Oin. 



6. In Journ. Eoy. Inst. Corn. vol. iv. p. 204, etc., Mr. Henwood 

 gives the following sections in two places, where the bed of Eestron- 

 guet Creek is some 12 feet below spring-tide high-water. 



A. Section 1. — 



1. Mud of the river, very soft 



2. Mud and coarse sand- 



3. Mud (hardened) 



4. Mud (with numerous oyster shells) 



5. Mud (hardened) 



6. Tin ground, 6 inches to 6 feet thick 



Shelf of buff or blue clay slate. 



B. Section 2.— 



1. Soft river mud , 



2. River sand and mud 



3. Blue mud (shells of oyster, cockle, etc.) .. 



4. Stiff blue mud without shells 



5. Tin ground ; subangular masses of granite, slate, elvan, 



quartz, etc., and tin ore in large masses interspersed with 

 smaller grains, 6 inches to 6 feet thick ; ... averaging 4ft. Oin. 

 Shelf of clay-slate. 



De la Beche (Eeport, p. 403). Up the Carnon Valley in the direc- 

 tion of St. Day, the tin ground is partly covered by marine sediments, 

 partly by common river detritus. 



Carnon. Mr. Carne mentioned (T.K.Gr.S. Corn. vol. iv. p. 105) 

 some beds of slate found reposing on the tin ground in the Carnon 

 Yalley, unconnected with the sides and bottom. 



DECADE II. — VOL. VI. — NO. VI. 17 





6ft. 



Oin. 





8ft. 



Oin. 





6ft. 



Oin. 



. ... 



12ft. 



Oin. 





31ft. 



Oin. 



averaging 



4ft. 



Oin. 



. ... 7ft. 



to 9ft. 



Oin. 





9ft. 



Oin. 







9ft. 



Oin. 



... ... 



36ft. 



Oin. 



