VALLEY AND ITS l^ELATION TO THE WESTLETON BEDS, ETC. 163 



(one small block measured 4 inches each way) and ragstone 

 imbedded in a bright ochreons clayey sand. I found no pebbles of 

 the older rocks. 



Bagshot Sands, 30 feet thick, and overlain by from 2 to 3 feet of 

 a ferruginous pebble-conglomerate, cap Boyce Hill (200 feet), near 

 South Benfleet *. Two to three feet of a Drift-gravel overlie the 

 conglomerate. 



Langdon Hill. — Eight miles westward of these hills, and 

 separated by a low tract of nearly bare London Clay, is Langdon 

 Hill the highest (373 feet) in South Essex. It is capped by some 

 40 or 50 feet of Bagshot Sands, over which is a thin sprinkling of 

 gravel, composed almost entirely of flint-i^ebbles, with which are 

 mixed a few subangular flints, and some very much weathered 

 fragments of chert and ragstone (PI. VTT. fig. 4). 



The Glacial Beds to the north do not approach within some miles 

 of Langdon Hill, and then they are on a much lower level (150 to 

 200 feet), as they are also at Bayleigh. 



Hampstead and Hufligate. — On the Bagshot Sands at Hampstead 

 there is in places a thin sprinkling of flint-pebbles (Bagshot), mixed 

 with which I have found a few subangular fragments of flint and 

 of a cherty ragstone, whilst at Highgate we can only surmise that 

 similar traces occur ; but the ground is too much built over for any 

 sufficient observations to be made. The relation of this Drift to the 

 Glacial Beds is here much the same as that of the Westleton Beds 

 at Totteridge to the Glacial Beds at Whetstone — that is to say, that 

 in both places the Glacial Beds are about 100 feet lower than the top 

 of these hills. At Highgate the Boulder-clay comes in at the foot 

 of the south slope of the hill (PL YII. fig. 3), and is not met with 

 higher. 



The summits of Hampstead Hill, and of Mill Hill near Tot- 

 teridge, are nearly on the same plane, whilst the summits of 

 Langdon Hill and Rayleigh Hill difl'er little from the height of 

 Brentwood and Writtlepark hills. In the latter instances, the 

 Westleton Shingle seems to be on a level somewhat lower, 

 although it is at a sufficient distance for a slight alteration in the 

 dip to lessen or annul the diff'erenco. The dip, however, of the 

 Westleton Beds is in general southward, and not northward. 



On the whole, these Drift-beds show more analogy with the 

 Southern Drift than with the Westleton Beds. It is possible, how- 

 ever, that in the case of Hampstead Hill the two may have had 

 the same floor and got intermixed. In the case of the Essex Hills, 

 there may be a connexion with the Brentwood group, but further 

 research is required to decide the exact relation of these drifts. 



The Brentwood Group. — The other hill-drift of this section may 

 be termed the Brentwood or Warley (jroup, from its being best 

 developed in that part of Essex, where it forms a number of 

 detached outliers. The most eastward of these hills are those 

 which range from a little west of Chelmsford to near Brentwood, 



* This would seem to indicate a fault between this spot and Eayleigh. 



