W. A. E. ZTssher — Pleistocene Geology of Cornwall. 259 



Mr. Hen wood (T. E. G. S. Corn. vol. v. p. 129) said that the 

 valleys between Breague Church and Porthleven, and from Helstou 

 to the Loo Pool, have been streamed for tin. 



Penzance District. 



8. A. Mr. Henwood (op. cit. p. 34) gives a section in the valley 

 between Huel Darlington and Marazion Mine near Newtown, at 20 

 to 30 feet above the sea. Sea sand with shells was found on 

 vegetable matter, with trunks and branches of oak, willow, hazel in 

 abundance, resting on poor tin ground on shelf at about the level of 

 the sea. 



B. At Tregilsoe (Tregilliow), on the confines of Ludgvan and St. 

 Hilary, a section of the short shallow vale terminating in Marazion 

 Marsh is given by Mr. Henwood (Journ. R. Inst. Corn. vol. iv. p. 

 197). Peat about 6 feet in thickness rests on the tin ground, 

 divided through its entire width by a thin seam of clay, impervious 

 to water, and running obliquely both to the shelf and to the surface. 

 Above the clay seam, the gravel consists of angular and subangular 

 masses of slate, quartz, veinstones, granules of crystalline tin ore, 

 all imbedded in bluish clay. Below the clay seam, slate pebbles 

 still prevail ; elvan nodules are not uncommon, but the quartz is 

 smaller and less frequent. Tin ore is diffused through the tough 

 reddish-brown clay matrix. Although within a mile of granite no 

 trace of granitic matter was found in these works. 

 Land's End District. 



9 A. (Henwood, op. cit. p. 195). Near Bejowans, in Sancreed, 

 section of a confluent with the little vale from Tregonebris to the 

 coast at Lamoma. 



1. Granitic sand and gravel 'with small angular and sub- 



angular stones 6ft. to 12ft. Oin. 



2. Peat -with nuts, branches, and roots of hazel 2ft. to 8ft. Oin. 



3. A few inches of granitic sand, gravel, and pebbles, with 



occasional large granite boulders like the tin ground. 



4. Tin ground, rounded masses of felspathic granite and 



tin ore, fragments of veinstones and quartz crystals 2ft. to 9ft. Oin. 



B. Mr. Henwood (op. cit. p. 193) mentions the sprinkling of tin 

 ore on S.E. of St. Just, in the southern and central parts of a ravine 

 trending from Kelynack north-westward to Pornanvon. He gives 

 a section at Bosworlas, in a narrow strip of virgin tin ground. 



1. Vegetable mould, in some parts of the glen succeeded by 2ft. or 3ft. 



2. Granitic gravel, sprinkled sometimes with tin ore ... a few inches. 



3. Tin ground of granitic matter, subangular and rounded 



tin-bearing veinstones, pure tin stone, subangular or 



angular 3in. to 2ft. 6in. 



The surface of the tin ground maintains a tolerably uniform sea- 

 ward slope throughout the ravine. 



C. (op. cit. p. 196). Between Towednack Church and Amellibrea, 

 in the lower part of Cold Harbour Moor. 



1. Peat ... 2ft. 6in. 



2. Granite detritus; mixed with blue clay, and unproductive in 



the upper part ; buff and reddish brown, with a little tin ore 



and tin-bearing veinstones in the lower part 3ft. Oft. 



B. On Leswhidden and Bostrase Moors, Mr. Carne (T.E.G.S. 



