

TIIK PLIOCENE SEIMKS .V.). r 



bones and teeth, and some sharks' teeth which are probably of 

 Pliocene age, such as Odontaspis hastalis and Carcharodon Rondeleti. 



Aliove tin- nodule bed there are yellowish marly sands and fine 

 quartz sands, with layers of comminuted shells, from 30 to 40 feet 

 thirk, and these form the lower portion of the Crag; above them 

 at Sutton, Gedgrave, and Aldeburgh come about 36 feet of a soft 

 porous yellowish-brown calcareous rock, consisting largely of com- 

 minuted shells and fragments of Polyzoa, which are often arranged 

 in oblique lamina-, while the bedding is of that irregular kind due 

 to the action of rapid and changeable currents. This soft limestone 

 has probably been formed by the infiltration of carbonate of lime 

 from the overlying Red Crag. Fossils are abundant in both portions. 



The Mollusca of the Coralline Crag (if they are not drifted) 

 indicate a sea of some depth (40-60 fathoms), with warmer water 

 than that of the existing North Sea. According to S. V. Wood's 

 summary in 1874 the total number of species was 391, of which 

 142 were extinct, while 249 are identical with recent forms. Of 

 these living species 205 occur in the Mediterranean, while only 

 174 occur in British seas, 50 being Mediterranean species which 

 Are not British, and 20 British species which are not Mediterranean. 

 Wood has also pointed out " that the most abundant and therefore 

 the most characteristic species of the Coralline Crag are southern 

 species unknown to British seas, and that among the 154 which 

 occur both in British and Mediterranean waters there are many 

 which are really characteristic Mediterranean shells, and are only 

 marked as British in consequence of some rare occurrence." 



St. Erth Beds. At St. Erth, near Hayle in Cornwall, and at 

 an elevation of about 100 feet above the sea, there is an interesting 

 deposit of sand and clay, the latter containing shells which prove 

 it to be of Pliocene age. A pit near the vicarage exposed the 

 following beds : 



F.'.-t. 



Loamy clay full of angular stones . . . . . . 2 to 6 



Fine gravel and coarse ferruginous sand . . . . . 4 to 6 



Clay, yellow above, blue beneath, and containing many fossils 6 



Fine foundry sand, base not exposed ?10 



The number of Mollusca which have been found in the clay is 

 between eighty and ninety, and the greater part of them are such 

 AS occur in the lower part of the Red Crag, but many species of a 

 southern character are present, such as Fusus corneus, Nassa recti- 

 costata, Nassa mutabilis, Cardium papillosum, and Cardita aculeata, 

 which do not occur in the eastern crags, while the Boreal and 

 Arctic forms found so abundantly in the higher part of the Red 

 Crag are absent at St. Erth. 



