﻿128 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Jan. 22, 



2nd. Superficial beds of sand, shingle, and marine shells, at greater 



elevation than the foregoing. 

 3rd. Great masses of detritus accumulated under atmospheric agen- 

 cies and ending abruptly at the former sea-level, No. 1. 

 4th. Marine beds, subjacent to the foregoing, and attaining an eleva- 

 tion of from 60 to 70 feet above the present sea-level. 

 Such is a broad outline of certain changes, and which represents 

 the extreme ranges of sea-level, at given definite periods, rather than 

 the progressive stages by which they have been brought about. The 

 Cornish valley sections, at one period — those of some of the river 

 valleys of the French coast — the section described by Capt. James at 

 another, might be made to represent transitional oscillations of small 

 amount ; but some of these phenomena may also be accounted for by 

 such temporary changes as are now produced at the openings of valleys 

 by the accumulation of banks of sand and shingle, and their subse- 

 quent removal. 



Having so far confined myself to a brief and chronologic account 

 of the evidences of certain changes of relative levels and former con- 

 ditions of surface, I will now endeavour to assign to each its place 

 and bearing in the physical history of the newer tertiary period. In 

 a former communication (Quart. Journal, vol. vi. p. 88) I have given 

 some reasons for considering the oldest marine beds here noticed 

 (1, 1, 1, 1, in Sections, PI. VI.) as referable to the pleistocene period 

 of Sir Charles Lyell. By <c pleistocene," however, I would merely be 

 understood to mean generally the period which is marked by the first 

 appearance of a northern marine fauna in sea-beds in our latitudes ; 

 or if this term is to be extended to the whole of that period which is 

 subsequent to the first appearance of such marine forms, I shall 

 endeavour to show that it was not one either of transitory duration, or 

 of one uniform set of geological results ; that although the mechanical 

 effects or products of given areas of sea may be inconsiderable when 

 compared with the formations of older periods, yet that the changes 

 which followed the red and coralline crag period, indicate more 

 contrasting conditions in physical geography than those of any other 

 period with which we are at present acquainted. 



It is however much to be hoped that the term Pleistocene, as well 

 as its kindred subdivisions of the tertiary period, will ere long disap- 

 pear from our geological nomenclature. 



The sea which accumulated the red and coralline crag extended 

 over and had its limits, on one side, on what is now part of the land of 

 East England, with a much wider range over that of the continent of 

 Europe on the other, thus indicating the existence at that time of an 

 amount of depression over the German Sea area which the area of 

 the English Channel had not. If any beds of the age of those in 

 question occur in the valley of the Channel, it can only be at consi- 

 derable depths beneath the present sea-level, otherwise some of the 

 Crag forms would necessarily be occasionally washed up ; we have no 

 single fact at present to lead us to suppose that beds of this age occur 

 there at all, whilst many other considerations tend to refer the area 

 of the English Channel, during this period, to the condition of dry 



