58 Royal Society : — 



allow time for a fuller investigation of the physical phenomena. The 

 points then sought to be established were, — the artificial make of 

 the specimens, — their position in undisturbed ground, — and their 

 contemporaneity with the extinct animals. The points for present 

 consideration relate to the structural and physical phenomena, and 

 to various theoretical questions. 



In the present paper the author proceeds to show that the flint- 

 implements are found along the line of existing river-plains at heights 

 varying from 20 to 100 feet above the rivers, and that the beds of 

 sand and gravel in which they are imbedded can be divided into 

 two more or less distinct series, one continuous along the bottom of 

 the valleys and rising but little above the river-level, and to which he 

 proposes to apply the term " Low -level Gravels," and the other in 

 detached masses on the heights flanking the valleys, and at 50 to 

 200 feet above the rivers, and which he designates as the " High- 

 level Gravels*." Both gravels consist of debris derived from 

 rocks in the valleys through which the present rivers or their tribu- 

 taries flow, and they both occasionally contain organic remains ; 

 both are, in fact, related to former plains and present valleys. 



This structure is then shown to apply to the Waveney, where 

 there is a tei'race of gravel on both sides of the valley at a level of 

 about 40 feet above the river, and to which position, but to a more 

 lacustrine condition, the Hoxne deposit belongs. Sections are given 

 of this valley, and also of the valleys of the Lark at Icklingham and 

 of the Ouse at Bedford, showing the constancy of this structure. 

 In the valley of the Thames the phenomena are more complicated 

 and are reserved for future consideration, notice being merely taken 

 of the implements found at Heme Bay and Whitstable. 



Owing to the absence of marine newer and post-pliocene beds in 

 the North of France, these gravels are better exhibited and more 

 distinct, being free from rock-fragments and boulders foreign to 

 their own origin and area. Hence it has arisen that this part of the 

 geological series has been more investigated in France than in 

 England. In the admirable review of the Quaternary formations by 

 M. d'Archiac, two general conclusions are set forth. With the first 

 of these the author perfectly agrees. It is that each large hydro- 

 graphical basin, although the boundaries may not be marked by any 

 important elevation, has its own exclusive drift, and that in no case 

 is there a mixture of the transported materials of the separate basins. 

 The author, however, dissents from the opinion that these drifts, 

 containing the remains of large extinct mammalia, have in any way 

 depended on or resulted from any general cataclysm destroying these 

 creatures nearly simultaneously over wide continents and entombing 

 their remains in the sand, gravel, and shingle of the valleys and 

 in the earth of the caverns ; neither can he consider the excava- 

 tion of the valleys to be anterior to the spread of the drift-gravels. 



* At the reading of this paper, the author used the terms "Terrace Gravels" 

 and " Valley Gravels ;" but he thinks it better to revert, with limitations, to tenns 

 which he suggested some years since, but has not hitherto defined. 



