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



mural escarpment^ having its crest and base frinf^ed with foliage^ and resting 

 upon a green talus of Gault. This base of clay after the wet winter of 1774 

 (see White's Hist, of Selborne^ letter 45) gave way under the superincumbent 

 pressure, occasioning the well-known Hawkley Slip, by which houses and 

 barns were displaced or thrown down. The surface of the Gault was rent into 

 fissures, and a large portion of the debris of the Malm-rock was ingulfed. 

 The subsidence of the Gault between Luccombe and Bonchurch, in the Isle of 

 Wight, has more recently occasioned a similar fall of the Undercliff. — It may 

 be stated, as an inducement to the traveller to diverge from the high road into 

 this district, that the deep and woody glens which intersect the escarpment of 

 the Malm-rock, olTer the most picturesque varieties of landscape. 



II. Gault. 



Below the range of the Malm-rock is seen a continuous breadth of Gault. 

 This stratum is most clearly developed at the north-eastern angle of the 

 district; where it forms the valley under Bentley and Binsted, and then rises 

 into eminences which compose the forest of Alice Holt. The superior bed is 

 commonly a brown or yellowish clay ; but on penetrating a few feet, blue 

 harsh clay is reached, which generally effervesces with acids, and appears to 

 be of uniform character throughout, in the deepest sections. On the surface 

 of Alice Holt there is frequently a diluvial covering of red and yellow flints, 

 which in some places is from 12 to 14 feet thick ; and where this occurs, water 

 has been procured by sinking merely through this gravel ; whilst in other 

 parts, the subjacent blue clay has been penetrated to the depth of 40 feet un- 

 successfully. Of the fossils of this formation I have met most frequently with 

 the Ammonites dentatus, at 6 or 8 feet below the surface. The junction of the 

 Gault with the Lower Green-sand is clearly exposed at the south end of the 

 village of Wracklesham, where the superior beds of the latter formation are 

 similar to those, of which specimens have been brought up by boring through 

 the Gault near Cambridge, and which are now in the museum of the Society. 



The agricultural character of this clay is unvaried in its whole extent from 

 Wracklesham near Guildford to the river Arun in Sussex. Its line is marked by 

 the most fertile water meadows and the finest forest timber ; thus presenting a 

 green belt, which clearly defines and distinguishes it from the rich wheat land of 

 the Malm-rock above, and the arid expanse of the Lower Green-sand below. 



III. Lower Green-sand. 



The Lower Green-sand is the most extensive formation in this district, and 

 presents an undulating and unequal surface. It rises from the valleys of Gault, 



