﻿352 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



which lie between the Lower Greensand and the Chalk with flints, 

 is for the most part exempt from such debris. This occurrence, 

 therefore, of broken flints of the Upper Chalk scattered at distances of 

 two to four miles from the escarpments of the South and North Downs 

 (including the Hampshire or Selborne range in the latter) leads me 

 to speak of it as having been chiefly distributed in a zone, lying be- 

 tween the chalk-escarpments of the South and North Downs and the 

 central dome of the Wealden. 



The features of this drift will be first described as they occur 

 under the western end of the escarpments of the South and North 

 Downs, in a district long familiar to me*. There I had been well 

 acquainted, for many years, with the existence of piles of sharply 

 fractured chalk-flints on the slopes of Lower Greensand, or filling 

 eroded cavities on the summits of the hills of that formation be- 

 tween Petersfield, Steep, and Sheet, and which extend by West Heath 

 and Rogate to Trotton and Midhurst Commons on the east. As this 

 band of sandstone is slightly coherent only, it disintegrates to loose 

 sand chiefly of ferruginous or whitish colours, on which, and in the 

 deeply eroded cavities of its surface, the flints are irregularly piled 

 up, at altitudes varying from 50 to 300 feet above the drainage of the 

 little river Rother and its affluents, and void of any signs whatever 

 of stratification. Such flint-drift may indeed be traced in a zone 

 from Stroud Common on the west by the low hills north of Peters- 

 field f to its greatest altitude on the edge of the escarpment of the 

 Lower Greensand overhanging the southern side of the remarkable 

 depression called Harting Combe. There the same debris has been 

 partially carried to the southern side only of the angle of Weald 

 Clay^ which is there denuded. The consideration of this point will 

 be resumed in the sequel. 



In the meantime, the accompanying woodcuts (figs. 2 & 3) will 

 serve to explain the relations which this flint-drift (x) bears to the 

 Chalk-hills on the north and south (c), and to the inferior formations 

 of Upper Greensand, Gault, Lower Greensand, and Weald Clay (d, 

 e, f, g), as they are exposed in the extreme apex of the Wealden de- 

 nudation near Petersfield. In fig. 2 the spectator is supposed to be 

 looking westwards from the west of Petersfield, where the chalk of the 

 North and South Downs is seen to be confluent near East Meon. I 

 will presently endeavour to show that it is from this western depres- 

 sion and fracture of the Chalk that the flints spread over the surface 

 of the Lower Greensand must have been derived ; seeing that they 

 can be continuously traced up to it. On the other hand, the flanking 

 strata of Gault, Upper Greensand or Malm Rock, and Lower Chalk 



* See Memoir on Parts of Surrey, Sussex, and Hants, Trans. Geol. Soc. vol. ii. 

 N.S. p. 97 et seg., and Map and Section, PI. XIV. 



f The top of the tower of Petersfield Church was fixed by the Ordnance Sur- 

 veyors to be 254 feet above the mean tide-level of the sea, and I estimate the 

 summit of Rogate Common as probably 300 feet higher. 



% In my published map, Trans. Geol. Soc. N. S. vol. ii. PI. XIV., and in all 

 the maps which have followed, the surface of Harting Combe is represented as 

 Weald-clay only ; but I have little doubt that if lateral excavations were made, the 

 Atherfield beds with Neocomian fossils would also be found there. 



