Dr. FiTTON on the Strata below the Chalk. 149 



nearly horizontal, though with an irregular surface, including flat nodular con- 

 cretions of iron pyrites, also horizontally disposed. No fossils were visible; 

 hut from the situation and characters of the clay, it seemed most probably 

 to be that of the Weald, brought up into this close proximity to the chalk, 

 by the general elevation of all the strata. It is indeed probable that the 

 Weald clay is very near the surface in many other places ; but as the middle 

 o-roup of the sands is also retentive of water, and capable of sustaining ponds, 

 the distinction can be ascertained only by attention to local circumstances. 

 The difference of level is so small in the different portions of the Wey, 

 from Pease-marsh, by Godalming, Pepperharrow, Elstead, and Tilford, that 

 this clay may be the base of the stream throughout ; but many of the ponds 

 which occur at higher levels, in the tract between Dorking and West Sussex^ 

 may safely be referred to the middle group of the sands *. 



(65.) Tuckshury-hill\ , Sgc. — The summit of this hill, which forms the 

 northern extremity of the section, Plate X. a. No. 4. is an outlier composed 

 of siliceous and ferruginous sand, upon the surface of which are numerous 

 angular fragments of pale yellowish flint. The ground descends from it 

 on all sides, but with the greatest rapidity towards the valley of the Wey ; 

 and it affords an excellent view, both of the successive outcrop of the strata 

 in the lower country, on the south-east, and (especially) of the tract on the 

 north, occupied by the Bagshot sands];, to which the cap of the hill 

 seems to belong ; the flat-topped ranges and the lower barren tracts of 

 that formation being seen from hence very distinctly. The summits of 

 Romping-down and Chobham-ridge project above the surrounding country, 

 with escarpments towards the east, nearly at right angles to the range of 

 the Chalk Downs ; but the general rise of the sands is towards the south, 

 conformably to that of the chalk §. The succession of strata observable in 



* Such are probably the ponds of Berry-hill, Lonesome, Wotton, and Abinger, near Dorking ; 

 of Thorncombe-street, Wormley-heath, Witley, and Lea-house, near Godalming ; Frensham 

 Great Pond ; and many of the pieces of water in Woolmer Forest. Several of the ponds near 

 Pulborough can with certainty be referred to the geological place mentioned in the text. 



f This name of the hill is taken from the Memoir connected with Mr. Greenough's map. In" 

 the Ordnance map, one point on the summit is called Farnham Beacon. 



\ Warburton : in Geol. Trans., 2nd Series, vol. i. page 48. 



§ I had proof of this rise, in passing along the main road from Guildford. At an early hour of 

 the morning, in October, all the flat country on the north was occupied by a dense uniform 

 fog, which filled the inequalities at the foot of the sand-heights on every side. Above this sea or 

 lake of mist, which afforded a sort of fluid level, the tops only of the ridges were visible, like long 

 dark islands, the southern extremities of which were uniformly higher than the northern ; the 

 intermediate line declining at a very small but perceptible angle. 



