PLIOCE:PfE PEKIOD IN EliGLAlTD. 473 



with the easterly diminution in tlie submergence described in the 

 sequel, shows clearly that in this direction the water became too 

 shallow for the bergs to pass further ; but the water deepening, as 

 we shall see, southwards, some passed in that direction, so that the 

 marl masses are imbedded mbS at Blaxhall, in the south-east of 

 Sheet 50 ; and were not the intervening space almost all concealed 

 by the pall of d, they would probably be found there also. 



Brickearths anterior to the Chalky Clay are noticed in the Geo- 

 logical Survey Memoirs as occurring in the north-west of Sheet 

 64 ; and Mr. Harrison, of the Leicester Museum, informs me that 

 the beds of Stage III. are at Oadby, in the north of Sheet 63, under- 

 lain by a bed of brickearth ; but with the exception of a brickearth 

 with beds of gravel containing derived specimens of the Portlandian 

 Ostrea eccpansa at Stevenage (in Sheet 46), which I regard as hS, 

 no clear evidence of the Contorted-Drift brickearth is to be found 

 south of the Stour river, but in lieu of it beds of gravel range to 

 great elevations all over the south of England ; and these I propose 

 now to trace. 



Southwards from the point at which this Drift ceases we find 

 gravel extending from the bottom to the top of Danbury HiU, and 

 crowning it at an elevation of 367 feet, as is the case with the 

 Tiptree ridge (shown in fig. YII.), a few miles to the north of it, 

 and of which the elevation is less. The highest hills in the south 

 of Sheet 1 are formed of outliers of the Lower Bagshot, ranging at 

 elevations of from 300 to upwards of 400 feet ; and on these there 

 is generally no gravel but that of pebble-beds (marked viii. in 

 fig. YI.)? which are either of Bagshot or, more probably, of Diestian 

 age. Nevertheless these were evidently once covered with this 

 gravel; for on one of them, that of Warley, at the elevation of 

 370 feet, I found a patch of it a few feet thick, exposed in digging 

 the foundation of a house. It was composed of large subangular 

 flints, of smaller flints, of the Diestian pebbles (probably also of 

 Lower Tertiary pebbles), and pebbles of quartz, quartzite, and sand- 

 stone. Billericay Hill, in fig. YL, being identical in its position 

 relatively to the Chalky Clay with Warley Hill, and of nearly similar 

 height, I have indicated by an asterisk in that figure the place on 

 Billericay Hill which would correspond to this on Warley. 



On the line dividing Sheets 1 and 6 the gravel occurs on the 

 summit of Telegraph Hill, Swanscomb, at an elevation of about 

 400 feet*. 



On Hampstead Hill top, near the Spaniards, at an elevation of 

 440 feet, a very small patch of this gravel remains, and is shown in 

 the Geological Survey Map of Sheet 7. In the north of Sheet 6, at 

 an elevation of 557 feet, gravel occurs on Well Hill, which is on 



* The Ordnance records do not contain the elevation of this hill; but, from 

 a surface-mark of 325 feet to the south-west of it, its elevation cannot, I think, 

 be much under 400. I have to thank the Director of the Ordnance Survey for 

 information as to the elevation of some of the places referred to in this memoir, 



a.J.G.S. No. 144. 2 k 



