THE UNDERCLIFF. 237 



through the upper porous strata, and projecting 

 in a ledge forms the bed of the stream that falls in 

 a cascade over the face of the cliff. 



In reference to the springs along this coast 

 it may here be remarked, that no less than ten 

 copious streams issue from the strata on the south 

 side of the range of hills facing the Undercliff, 

 and run directly into the sea ; most of those 

 which flow from the greensand are chalybeate. At 

 Sandrock, near Blackgang, is a celebrated alumi- 

 nous chalybeate spring, of which an analysis was 

 published by Dr. Marcet in Geol. Trans, vol. i. 

 This water is highly charged with sulphate of iron 

 and alumina ; it rises from a bed of sand within 

 fifty feet of the gait. 



The Undercliff. — We have now arrived at 

 the western extremity of that interesting and pic- 

 turesque region known as the Undercliff of the Isle 

 of Wight ; and which may be described geologi- 

 cally, as a miscellaneous accumulation of debris, 

 principally composed of fallen masses of the upper 

 cretaceous strata, occasioned by the encroachments 

 of the sea on the lower argillaceous and sandy de- 

 posits that form the base of this line of coast. The 

 Undercliff consists of an irregular terrace, sloping 

 towards the south, from a quarter to half a mile 

 in breadth, and six miles in length ; its elevation 

 o2 



