216 GEOLOGY OF THE ISLE OF WIGHT. 



lowermost bed of the greensand is in contact with 

 the wealden clays, the distinctive characters of the 

 marine and freshwater deposits may sometimes be 

 observed in a mass of the stratum but a few inches 

 thick ; marine shells appearing imbedded in the 

 upper layers, and freshwater shells in the lower 

 portion. 



Pebbles and shingle. — Before we ascend the 

 cliff to pursue our excursion towards Atherfield, 

 I would offer a few remarks on the sea-beach. 



The beds of shingle along this coast, consist in 

 a great measure of chalk flints that have been 

 broken and rounded by attrition into boulders, 

 pebbles, and gravel. This is evident from the 

 peculiar aspect and fracture of the stones, and the 

 nature of their organic remains, of which some 

 traces are generally manifest. The clear transparent 

 pebbles, with bands and veins of quartz and chal- 

 cedony, which in some specimens are as clear as 

 crystal, and in others of a bright yellow, amber, 

 dark brown, and bluish-black colour, have a 

 similar origin. The moss-agates,* as they are 

 called by the lapidaries, are silicified chalk 

 sponges ; and the beautiful fossils {Choanites)-\ 

 commonly known as " petrified sea-anemones,' 1 '' are 



• Not the German moss-agates exhibited in the shops as the genuine pro- 

 ductions of the Island. Sec note In page 18. 

 I " Thoughts on a Pebble," pi. 1 and 2. 



