AUSTEN TERTIARY DEPOSITS OF THE SUSSEX COAST. 55 



of the waters of the channel, which permitted southern forms to take 

 a more northern range than at present ; and 2ndly, of a hmitation of 

 these forms to the area of the Channel. 



Without entering at present on the question of the relative age of 

 the older beds of the Sussex levels, as compared with the Crag 

 deposits of the Germanic basin, it is clear, even from this short list 

 of species, that the physical conditions which caused this limitation 

 may be carried back in time : the English Channel may not have 

 existed as an internal sea at the time of the accumulation of the Crag 

 series ; but, if it did, a natural bar was interposed, and the waters 

 of the two areas did not communicate as they do at present ; nor 

 did they communicate with each other until after that climatal change 

 which caused the southern formxS to retreat from our shores. 



The inference to be derived from the manner in which the Elephants* 

 remains occur in this deposit is an obvious and an interesting one, 

 inasmuch as we thereby arrive at a relative geological date, which 

 is this, — that the lower estuarine beds of Selsea and of the Sussex 

 levels generally were contemporary with what is known as the period 

 of the Large Mammalian fauna. It is, moreover, equivalent as to 

 time with the subaerial accumulations of the chalk- downs, as at 

 Peppering in the Valley of the Arun (beneath which an entire 

 skeleton of an Elephant was found by Mr. Drewett), and of all the 

 peat and freshwater beds of the valleys of the Wealden area, in 

 which the remains of this animal have been met with under like 

 circumstances. 



Some terms have of late crept into very general use in descriptive 

 geology, and to which a sufficiently definite meaning has not been 

 attached : thus certain gravel-beds, which in this country have a 

 most extensive range, are commonly designated as "Elephant-gravel,'* 

 as if the presence of such remains was alone sufficient to mark a 

 geological date. It must be borne in mind that fossil remains are 

 only truly characteristic of any beds when they necessarily belong 

 to the time and conditions under which such beds were formed. 

 Certain assemblages of shells indicate salt, brackish, and freshwater 

 conditions ; but, though the remains of terrestrial animals may in some 

 cases be carried out and mixed up with the exuviae of the marine 

 deposits of their time, such cases must be considered as exceptional. 

 With respect to the gravel-beds in question, the presence of the 

 Elephants' remains is owing to the circumstance that vast numbers 

 of these animals had occupied a given area, and left their remains 

 there anterior to the accumulation of the said gravels. The remains 

 of the Elephas primigenius belong to a period of wide-spread ter- 

 restrial conditions ; the gravel-beds which contain the detached and 

 harder portions of their remains show to how great an extent the 

 area of these terrestrial conditions was submerged. 



This consideration equally applies to the case of the Mammalian 

 remains which are found in the tipper Crag of Norfolk and Suff'olk. 



2. Yellow Drift Clay. — The next accumulation which, in parts of 

 the coast-section, overhes the marine deposits with Lutraria rugosay 



