148 



PEOF. PRESTWICH OX THE AGE, FORMATION, AND 



found ; and as this stream of gravel sweeps round the hill, it catches 

 up from the eastern branch and other affluents a quantity of 

 Lower-Greensand debris, so that, on the other side of the hill, 

 between iS^ew Earn and Rye House, it contains a large proportion 

 of Chert and Eagstone, together apparently with some of the 

 Broughton-Hill gravel trailed down the hill. The features distin- 

 guishing these two gravels are : — 



1. The larger proportion of Tertiary flint-pebbles, and of brown- 

 stained worn flints, in the Broughton-Hill bed, and its well-marked 

 stratification. 



2. The great preponderance of angular and subangular flints in 

 the Dunton-Green bed, and its want of stratiflcation. 



The railway- cutting at Dunton Green was too far advanced when 

 I first saw it, and the gravel-bed too massive, to mark the peculiarity 

 of its junction wdth the Gault shown in the longer shallow cutting 

 between Chevening Cross and Combe Bank Wood, where the 

 sections were at first sight curiously deceptive. The sides of the 

 cutting, which had been reduced to a slope of about 30°, presented 

 the appearance shown in fig. 8, exhibiting loops sloping downwards 

 and sideways towards the west ; while on the south side of the 

 cutting they sloped towards the east. But where the side had been 

 left vertical the section was as represented in fig. 9. The appear- 

 ances of distortion are therefore due solely to the obliquity of the 

 plane intersecting the cylindrical segments of gravel *. 



Pig. 8. — Cutting, 5 feet deep^ on north side of the line between 



Comhe Bank and Chevening, after being sloped down. 

 W. E. 



Fig. 9. — Cutting on north side of the line hy the bridge adjoining 

 Combe Banlc, before being sloped doivn. 



E. 



(1. Unstratified gravel, sand, and clay. This bed consists of two parts, which 

 pass one into the other — a lower one of coarse gravel in a matrix of 

 ferruginous loam and sand, mixed with some clay from the Gault ; 

 and a thin upper one, d', which spreads nearly uniformly over the 

 whole, of a light-brown clay (altered Gault) mixed with a few flints. 

 3. Bluish-grey Gault. 



The gravel in d consists of: — 



Angular and subangular white flints in larger part. 



Some Tertiary flint -pebbles. 



A few small blocks of Tertiary sandstone and ironstone. 



* A full explanation of this phenomenon is given geometrically by the Rev. 

 O. Fisher, Geol. Mag. dec. ii. vol viii. (1881) p. 20. 



