9ft. 



Oin. 



20ft. 



Oin. 



Oft. 



3in. 



2ft. 



Oin. 



3ft. 



Oin. 



106 W. A. E. Ussher — Post- Tertiary Geology of Cornwall. 



(14) Messrs. Kitto and Davies give the following section on the 

 east of the Beacon (op. cit.) : 



Head 6ft. Oin. 



White candle clay 3ft. Oin. 



Gravel ]ft. Oin. 



White candle clay 2ft. 6in. 



Yellow and whitish sand not gone through. 



The following sections were taken in the isolated part of the 

 deposit on granite to the West of the Beacon : 



(15) Hawkins (op. cit.) — 



Yellow Cohh 4ft. Oin. 



Clay 6ft. Oin. 



Puddle sand (local name) 2ft. to 3ft. Oin. 



(16) Henwood, quoted from Mining Review (op. cit.): — Surface 

 418 feet above high water. Sand met with at 9 feet below the 

 surface ; 12 feet sunk through yellow sand of a lighter tint at the 

 base. 



(17) Messrs. Kitto and Davies (op. cit.) : 



Head 



Candle clay 



Dark red sand 



Yellowish sand ... ... 



Gravel, pehbles, boulders, and sand resting on granite 



34ft 3in. 



I observed four pits, all in the main deposit, and lying to the 

 northward of the Beacon, varying from seven to eleven feet in 

 depth ; the very impersistent nature of the clay and of the colours 

 in the sands was very noticeable. 



From the map and sections accompanying the paper by Messrs. 

 Kitto and Davies (op. cit.), it will be seen — that the clays are in no 

 place coextensive with the sands, although in parts their boundary 

 approaches very near to the limits of the deposit ; that they are the 

 thickest in the isolated patch on the granite (17), which lies in a 

 basin ; that the coarse detritus is of exceptionally local character 

 in the different sections, tin stone pebbles being confined to the 

 immediate vicinity of lodes. The appearances of bedding in the sand, 

 and the relative positions of the sands and clays in sections (1), 

 (7), and (8), are indications of a continuity of deposit, which the 

 variability of the other sections given shows to be abnormal. The 

 occurrence of quartz pebbles in exceptionally sandy overburden 

 (section 6), is worthy of note, and suggests the former overspread of 

 gravelly detritus, similar to the gravels of Crousa Down and 

 Crowan. 



The Head, as far as I observed it, consists of brown loam, with 

 angular fragments of local rocks derived from the hill above, 

 resembling, according to Messrs. Kitto and Davies, '* The soil and 

 subsoil found upon the Killas of Cornwall, except that it is some- 

 what sandy in parts and occasionally contains washed pebbles." 

 This Head, Overburden, or Cobb, is of like nature, and probably 

 roughly contemporaneous with the accumulations of stony loam on 

 the coasts hereafter to be noticed. The preservation of the deposits 



