1 50 Dr. PiTTON on the Strata below the Chalk. 



descending from the elevation to the valley of the Wealds, is very in- 

 structive. 



At the west end of the hill, beneath Warren's-corner, on the road to Basingstoke, Septaria are 

 found in a stratum of the London clay, which occupies a considerable thickness on the slope of 

 the hill, below the cap of sand. I was informed tliat " Pot-earth," of a different quality, occurs 

 lower down, in Clarehouse-Park, in the situation of the Plastic clay ; and I have seen the Chalk in 

 the decline of the hill, between Lower Old Park and Halfway-house. 



The Upper green-sand forms a slight prominence beneath this chalk, on the south of Dip- 

 penhall-house, between the words ' Dean's-farm ' and ' Ridgway ' on the Ordnance map, the strata 

 dipping not much more than 5° to the north. The rock, which is there called ' Marl-stone,' does 

 not precisely agree with any I have seen between this place and the coast, but is very like some of 

 the strata in the corresponding place at East Knoyle, on the north of the Vale of Wardour. It is 

 a subcalcareous sandstone, or variety of " fire-stone," very soft, uniform, of a yellowish-grey or 

 cream-colour, scarcely effervescent, and remarkable for its lightness ; and it includes concretions 

 of a hard splintery limestone, approaching to chert, and of much greater density than the stone 

 which surrounds them. 



The Gault, on the line of the section, first comes up on the road descending from Ridg- 

 way to the river Wey, but is more distinctly seen at the extremity of Wracklesham ; and, in 

 consequence of the more gradual rise of the strata, on the south-west of that village, it occupies 

 a more expanded surface in Alice-Holt Wood, as described in Mr. Murchison's paper above 

 referred to. 



On the south of the main London road, where it is crossed by the road to Wracklesham, is a 

 bank with the Lower green-sand at the bottom, rising towards the village. The surface is waved 

 remarkably ; and the inequalities are filled up with gravel, consisting of broken flint pebbles, in 

 large proportion, mixed with red loam, and in immediate contact with the yellowish sands below. 

 The top of the gravel, is nearly level; but its depth to the sand varies from 1^ to 4 feet. This 

 fact is analogous to the erosion of the sands near Dorking, mentioned above (56). 



(QQ.) The mode in which the drainage of the north-western portion of the 

 great valley of the Wealden is effected, and the different manner in which 

 the streams escape, in this part of the country, from that of their egress 

 through the North and South Downs, support the hypothesis of Mr. Scrope 

 and Mr. Martin, that the gorges themselves were not produced by simple de- 

 nudation, but at least prepared, by antecedent fissures cutting entirely across 

 the Weald : while the appearances of the surface, above described, are so 

 unlike those which would have been produced by rapid diluvial action, as to 

 indicate either a long period of submersion, at no great depth, or very gradual 

 drainage and long-continued decay. 



The principal branch of the Wey, from its rise near Alton, to Farnham, is nearly straight, in a 

 direction from south-west to .north-east ; but immediately below Farnham, instead of cutting 

 across the chalk downs, it turns abruptly to the south-east, to join another branch; which likewise 

 runs in a straight line nearly parallel to the former, from its source in the chalk near Selborne, 

 through Kingsley, by Frensham, to Tilford Bridge, where the streams unite: and then taking a 

 tortuous course, but in a general direction parallel to the Hog's-back, the river cuts deep 



