32 GEOLOGY OF THE ISLE OF WIGHT 



cliff to bring the lifeboat down. This was washed away 

 in the storms of the winter 1912-13. 



Above the Perna bed lies a great thickness of Atherfield 

 clay. Above this lies what is called the Lower Lobster 

 bed, a brown clay and sand, in which are numerous nodules 

 containing the small lobster Meyeria vectensis, known as 

 Atherfield lobsters. Many beautiful specimens have been 

 obtained. 



We next come to a great thickness of the Ferruginous 

 Sands, some 500 feet. The Lower Greensand of Atherfield 

 was exhaustively studied in the earlier days of geology 

 by Dr. Fitton, in the years 1824-47, and tne different 

 strata are still referred to according to his divisions. The 

 lowest bed is the Crackers group about 60 ft. thick. In 

 the lower part are two layers of hard calcareous boulder- 

 shaped concretions, some a few feet long. The lower 

 abound in fossils, and though hard when falling from the 

 cliffs are broken up by winter frosts, showing the fossils 

 they contain beautifully preserved in the softer sandy 

 cores of the concretions. Gervillia sublanceolata is very 

 frequent, also Thetironia minor, the Ammonite Hoplitcs 

 deshayesi, and many more. Beneath and between the 

 nodular masses caverns are formed, the resounding of the 

 waves in which has given the name of the " Crackers." 

 In the upper part of this group is a second lobster bed. 



The most remarkable fossils in the Lower Greensand 

 are the various genera and species of the ammonites and 

 their kindred. The Ammonite, through many formations, 

 was one of the largest, and often most beautiful shells. 

 There were also quite small species. The number of 

 species was very great. Now the whole group is extinct. 

 They most resembled the Pearly Nautilus, which still lives. 

 In both the shell is spiral, and consists of several chambers, 

 the animal living in the outer chamber, the rest being 

 air-chambers enabling it to float. The class Cephalopoda, 

 which includes the Ammonites, the Nautilus, and also the 



