VALLEY AJ^D ITS EKLATION TO THE WESTLETON JiEDS, ETC. 157 



much above the level of the Post-Glacial Drifts, contains no organic 

 remains, and is distinctly a plateau or hill-gravel. 



It is not, however, until we reach the neighbourhood of E-ochester 

 that the Southern Drift is found well characterized. It there caps 

 the wooded hill extending eastward, at a height of about 400 feet, 

 from the mausoleum in Cobham Park to within a mile of the Med- 

 way (see PI. YII. fig. 4). It is a coarse gravel, lying bare on the 

 surface, and consists roughly of * — 



1. Subangular flints but little stained, with others more worn and ^l ^ 



stained uuifoi*mly brown J 5 



2. Fiint-pebbles, some of them broken and white, with abraded 1 



edges, and green-coated flints from the base of the Thanet l-i- 



Sands J ' 



.3. Subangular fragments of chert and ragstone from the Lower 1 jl 

 Greensand, and a few pieces of iron-sandstone J ^ 



There is an absence of white quartz-pebbles. 



Traces of similar gravel occur a few miles to the south of the last, 

 on the hills between Hailing and Punish Farm, near the edge of 

 the Chalk-escarpment. 



On the high Chalk-plateau between the Medway and the Darent 

 there is in several places, namely at Ash, Pairseat, Plastal Green, 

 Wrotham Hill, Cotman's Ash, Bower Lane, and others, a thin sprink- 

 ling of this old flint- and chert-drift. But there is no bed of it, 

 except oji the isolated Tertiary outlier at Swanscombe Hillf, 3| miles 

 north of the main Chalk-plateau, where it forms a small patch, 316 

 feet above the sea-level, and almost identical in composition with 

 tlie gravel on Cobham Hill. 



A much more important bed of this character is one which I 

 met Avith long ago on the summit of Well Hill, near Chelsfield, a 

 ridge from 550 to GOO fcethigh, foni)i)ig the water-shed between the 

 Darent and the Cray, and extending about one mile from south to 

 north, with a width of only a few hundred feet. This bed of gravel 

 is from 5 to 12 feet thick, very coarse and unstratificd, and consists 

 mainly of : — 



1. Subangular flints, many of them very large and very much worn. 



and having the interior texture altered to an opaque white or brown 

 colour ; with a few smaller ones stained brown on the outside, and still 

 more worn. 



2. Numerous flint-pebbles (some of them broken and worn) from the 



Woolwich and Reading Beds, and a vei'y few green-coated flints from 



the base of the Thanet Sands, 

 ,*}. A very small number of subangular fragments of chert and ragstone. 

 4. A few rare flat ovoid white quartzites. 



The whole imbedded in ochreous quartzose sand and clay. This 

 Drift rests on an uneven surface of Lower Tertiaries, which forms an 

 outlier rising above the surrounding Chalk-plateau, see fig. 7, p. 170. 



* The relative proportions vary so much in different localities that it is not 

 necessary to describe it very closely. 



t I have described this bed in Quart. Journ. Geol. Soc. voL xlv. p. 291 (1880). 



