DRIFT-STAGES OF THE DARENT VALLEY. 147 



AVesterbam, but tbis has more the appearance of a wash from the 

 Gault. Mr. Topley mentions that a brick-earth 10 feet deep has 

 been dug near Sudbridge Church, and that brick-earth extends from 

 Dryhill eastwards towards Briton's Farm, which would be near 

 to the 400-feet contour-line. A newer brick-earth is worked 

 at Froghole Farm, near Chipstcad, overlying some Low-level 

 ground. 



The powerful scour of the waters, as they ran through the nar- 

 rower pass in the Chalk hills, has either not allowed of the lodg- 

 ment of brick-earth or else has swept it away, and it was not until 

 the current was checked near Dartford by its junction with the 

 Thames that sedimentation of brick-earth took place*. That period 

 may have been somewhat later. 



§ 7. Other Drifts of the Darent Valley : the Chevening 

 A^TD Duis^tox-Greex Gravel. 



A sprinkling of gravel is common over much of the lower grounds 

 of the Darent Valley, but it is only in a few places that the quantity 

 amounts to a well-defined bed, and the relation of these to one 

 another is more uncertain than is that of those belonging to the 

 Limpsfield level. I give them in what appears to me to be their 

 order of succession, but with the certitude only that they are all 

 newer than the Limpsfield bed. 



Tlie Chevening and Bunton-Green Bed. — It was not nntil the 

 railway from Duuton Green to Westerham was made (1881-82) 

 that the distinctive character of this gravel, or the fact that it was 

 anything more than a superficial trail, could be determined. The 

 railway sections then made it evident that it formed occasionally a 

 well-defined and more or less continuous bed, resting frequently upon 

 a very irregular surface of Gault — in the form of patches or pockets 

 of lesser or greater extent. 



At Dunton Green (the railway-bridge cutting) it forms a com- 

 pact and continuous deposit, without bedding, about 5 feet thick, 

 and composed, in the order of their relative abundance, of : — 



1. Large and small angular or slightly subangular flints (some stained 



through of a light yellow colour), these form the great bulk of the 

 gravel ; 



2. Some large, fresh-looking, perfectly angular flints 



3. A moderate number of Tertiary flint-pebbles and subangular fragments 



of Sarsenstone and Ironstone ; 



4. A very few well-worn brown-stained flints ; 



embedded without order in a matrix of red loam and sand. No 

 fossils and no flint implements have been found in this gravel. Its 

 level here is 270 feet above CD., or 87 feet lower than that of the 

 adjacent Broughton-Hill (PI. VI., fig. 1 and fig. 10) high-level 

 gravel, and there seems to be an absence of Chert and Kagstone. 

 But in a pit recently opened a few hundred feet south of the 

 railway bridge, a few rare pieces of cherty Ragstone are to be 



* The high-level brick-earths of the eastern branch of the Darent Valley 

 were noticed in the Ightham paper. 



