102 Mr. R. I. MuRCHisoN on the North-western Extremity/ of Sussex, 



The best quarries of this rock are north of Midhurst_, as at Dunner Hill^ 

 Pit's Hill, &c. &c. 



It is worthy of remark that this formation, though not retentive of water, 

 supports a vast number of small lakes or ponds. Those of Frensham, Wool- 

 mer Forest, Petersfield, Iping and Burton are examples. 



The river Wey (the principal branch of which rises in the chalk at Alton 

 from numerous and perennial spring's), after flowing- through the chalk, the 

 Malm-rock and the Gault successively, has its course exclusively in this 

 stratum for about 20 miles, until it turns to intersect the chalk-escarpment at 

 Guildford. In like manner the Rother, or western branch of the river Arun, 

 which rises in the chalk and flows over the intermediate formations, is in its 

 subsequent course confined to these sands ; passing- near Lyss, Petersfield, and 

 Midhurst, to its junction with the main branch at Pulborough. 



The depth of the wells in this formation increases with the rise of the hills. 

 At Petersfield water is reached in 20 or 30 feet ; at Rake common, in 200 feet ; 

 and in boring for water this summer at Petworth-house, near 400 feet of 

 sand were passed through, when a blue clay was brought up which effervesced 

 with acids. 



Diluvial accumulations of chalk flints sometimes occur on the surface of 

 these sands, as at Rogate Common, &c. and several beds of such debris were 

 cut through last summer near Trotton, in making the new road from Peters- 

 field to Midhurst. Their presence on this stratum is worthy of remark, as I 

 have never met with them on the subjacent formation of Weald clay. 



IV. Weald Clay. 



The Weald clay, which is next in the series, forms at Harting Combe the 

 nucleus of the western part of this district. — The line A B on the map, drawn 

 from this point west-by-north and south-south-east, shows a section complete 

 in all its members up to the chalk escarpment on either side. 



The passage from the lower green-sand to the clay is well observed along 

 the base of the hills which bound the valley on the south, where very thin 

 beds of various-coloured clays alternate with soft dark green-sand. These 

 striae seem to mark the dip, which is at an angle of from 10 to 12 degrees. 



The surface clay in the bottom of the valley is yellowish-brown in colour; 

 but changes below to a deep red, and is then highly impregnated with oxide 

 of iron. 



The general form of the valley in this part of the Weald is peculiar, and 

 the great inequality of its width is a striking feature in the geological map. 



From its western angle and commencement at Harting Combe, little more 



