Ch. XIV] LOWER MIOCENE, ISLE OF WIGHT. 239 



Between the Bolderberg beds and the Rupelian clay there is a great 

 chasm in Belgium, which seems, according to M. Beyrich, to be filled 

 up in the North of Germany by what he calls the Sternberg beds, and 

 which, had Dumont found them in Belgium, he might r robably have 

 termed Upper Rupelian. 



LOWER MIOCENE STRATA OF ENGLAND. 



Hempstead beds, Isle of Wight. — We have already seen that the 

 Upper. Miocene period is meagrely and somewhat questionably repre- 

 sented in England by certain ferruginous sands on the North Downs, 

 of the ao-e of the Diestian beds of Belgium. The Lower Miocene 

 period is more decidedly represented by certain strata in the Isle of 

 Wight, the true age of which was not recognized until the year 1852, 

 when the late Edward Forbes observed * that there was a series of ter- 

 tiary strata near Yarmouth newer than those of Binstead and Bern- 

 bridge. These last are the undoubted equivalants of the Paris gypsum, 

 being characterized by the same species of Paleotherium Anoplo- 

 therium, &c, as those described by Cuvier from Montmartre. The 

 Lower Miocene deposits alluded to are 170 feet in thickness and rich 

 in fossils, and have been called the Hempstead series, from a hill of 

 that name on the coast near Yarmouth.f The following is the succes- 

 sion of the strata : — 



SUBDIVISIONS OF THE HEMPSTEAD SERIES. 



1. The uppermost or Corbula beds, consisting of marine sands and clays, contain 

 Voluta Hathieri, a characteristic Lower Miocene shell, Corbida pisum, fig. 171, 

 a species common to the Upper Eocene clay of Barton ; Cyrena semistriata, fig. 

 172, several Cerithia, and other shells peculiar to this series. 



Fig. 172. 



Corbula pisum. Hempstead Beds, . Cyrena semistriata. 



Isle of Wight. Hempstead Beds. 



2. Xext below are freshwater and estuary marls and carbonaceous clays, in the 

 brackish-water portion of which are found abundantly Cerithium plicahcm, Lam., 

 fig. 173, 0. elcgans, fig. 174, and C. tricinetum ; also Rissoa Chastelii, fig. 175, 

 a very common Kleyn Spawen shell, and which occurs in each of the four sub- 

 divisions of the Hempstead series down to its base, where it passes into the 

 Bembridge beds. In the freshwater portion of the same beds Paludina lenta, 



* E. Forbes, Geol. Quart. Journ.,"1853. 



f This hill must not be confounded with Hampstead Hill, near London, where 

 the Lower Eocene or London Clay is capped by Middle Eocene sands. 



