3ft. 



Oin. 



Oft. 



lOin. 



2ft. 



Oin. 



12ft. 



Oin. 



3ft. to 4ft. 



Oin. 



12ft. 



Oin. 



18ft. to 22ft. 



Oin. 



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



C. Mr. Henwood (T.E.Gr.S. Corn. vol. iv.) gives the following 

 section of Carnon Stream Works, the letters denote beds probably 

 contemporaneous with those in the Watergate, Merry Meeting, and 

 Broadwater sections. 



a. Sand and mud ; 2 beds ; river wash 



2. Silt and shells ; 3 successive beds 



3. Sand and shells (a stream of fresh water percolates 



through this bed) .., ... 



4. Silt; 3 beds 



5. Sand and shells 



6. Silt with numerous shells . . . 



7. Silt with stones in places ... 



b. "Wood, moss, leaves, nuts ; dark coloured as if 



charred; a few oyster shells; animal remains, 

 chiefly cervine ; human skulls. Towards the sea 

 this bed gives place to silt (No. 7) 1ft. 6in. 



c. Tin ground, rounded tin ore, unmixed, and in a 



quartz matrix and capel (quartz and schorl) ; from 

 a few inches to 12 feet iu thickness ; ... averaging 4ft. Oin. 



Eounded pieces of slate, granite, and quartz, mixed 

 with the tin stones. 

 Mr. Henwood observes that above Carnon Section, either the old 

 forest never flourished, or it has been destroyed in the accumulation 

 of alluvia, in which periods of peat growth and transport of vegetable 

 matter are indicated. 



Mr. E. Smith gives a section of Carnon Works in 1807 (Geol. 

 Trans, vol. iv. p. 404). 



7. Sections given by Mr. Henwood (J. E. Inst. Corn. vol. iv. pp. 

 200, 201) which from similarity of names seem to refer to localities 

 lying between Falmouth and Helston. 



A. 1. The Upper part of Cam Wartha. 



1. Worn and unworn granitic detritus, mixed with lumps of 



peat, and refuse of previous operations 12ft. Oin. 



2. Tin ground — granitic sand and gravel, sprinkled here and 



there with waterworn granules of tin ore ; interspersed 

 at intervals with blocks of granite and schorl rock ... 12ft. Oin. 



Shelf of disintegrated granite. . 



B. At Lezerea in Mean Vroaz. 



1. Peat; with nuts and branches of hazel in deeper parts, in 



places 4ft. Oin. 



2. Coarse granitic gravel with occasional subangular stones 



of tin ore 2ft. to 3ft. Oin. 



3. Granitic sand, slightly mixed at intervals with felspathic 



clay 2ft. Oin. 



4. Tin ground, angular and subangular masses of granite 



and schorl rock, largely mixed with tin ore of different 



character from tbat at Cam Wartha 3ft. Oin. 



" In other parts of the Moor sections of ancient works show beds 

 of cletrital matter resting immediately on the outcrop of tin -bearing 

 veins in the granite." 



C. Near Tregedna in Mawnan (? at mouth of E. Helford) vegetable 

 mould and hardened silt, 20 or 30 feet thick, overlie a poor deposit 

 of tin ore resting on slate shelf. 



[Ibid.) Waterworn granules of pure gold have been found in 

 detrital tin ore (which is less rounded than in other parts of Corn- 

 wall) near Helston. 



