44 GEOLOGY OF THE ISLE OF WIGHT 



remains of the life of the ancient sea. The base of the 

 cliffs and fallen blocks on the shore are the best places to 

 find fossils. Much of the base of the cliffs is inaccessible 

 except by boat. The lower strata may be examined in 

 Sandown and Compton Bays, and the upper in White- 

 cliff Bay. A watch should always be kept on the tide. 

 The quarries along the downs are not as a rule good for 

 collecting, as the chalk does not become so much sculp- 

 tured by weathering. 



The deep sea of the White Chalk did not come suddenly. 

 In the oncoming of the period we find much marl limy 

 clay. As the sea deepened, little reached the bottom but 

 the shells of foraminifera and other marine organisms. 

 How deep the sea became is uncertain : there is reason to 

 believe that it did not reach a depth such as that of the 

 Atlantic. 



It is difficult to draw the line between the Upper 

 Greensand and the Chalk strata. Above the Chert beds 

 is a band a few feet thick known as the Chloritic Marl, 

 which shows a passage from sand to calcareous matter. 

 It is named from the abundance of grains of green colour- 

 ing matter, now recognised as glauconite ; so that it 

 would be better called Glauconitic Marl. It is also re- 

 markable for the phosphatic nodules, and for the numerous 

 casts of Ammonites, Turrilites, and other fossils mostly 

 phosphatized, which it contains. This band is one of 

 the richest strata in the Island for fossils. It differs, 

 however, in different localities both in thickness and 

 composition. It is best seen above the Undercliff, and 

 in fallen masses along the shore from Ventnor to Niton. 

 It is finely exposed on the top of Gore Cliff, where the flat 

 ledges are covered with fossil Ammonites, Turrilites, 

 Pleurotomaria, and other shells. The Ammonite (Schloen- 

 bachia varians) is especially common. The sponge 

 (Stauronema carteri) is characteristic of the Glauconitic 

 Marl. As the edge of the cliff is a vertical wall, none 



