103 



PROCEEDINGS 



THE GEOLOGICAL SOCIETY. 



POSTPONED PAPERS. 



1. On the Amiens Gravel. 

 By Alfred Tylor, Esq., F.G.S. 



(Eead Nov. 8, 1867^*.) 



[Plates III. & IV.] 



Contents. 



I. Introduction. 



II. Description of the Longitudinal 

 Section. 



III. Descriptions of the Transverse 



Sections. 



rV. Characters of the Chalk, Gravel, 

 and Loess. 



1. The Chalk. 



2. The Gravel and Loess. 

 V. Conclusion. 



I. Introduction. 



The exact position, character, and equivalents of the Quaternary- 

 deposits of the valley of the Somme have been frequently discussed. 

 On the authority of certain sections and plans of Amiens and Abbe- 

 ville, the correctness of which will be examined hereafter, theoretical 

 views concerning the relative ages of different parts of the gravel 

 and of different parts of the valley of the Somme have been promul- 

 gated by Mr. Prestwich, and repeated by Sir C. Lyell and others. 



These geologists have asserted : — 



Eirst, that there were two valley-gravels of distinct age at Amiens 

 and Abbeville, one named by them the upper and the other the lower 

 valley-gravel ; 



Secondly, that the upper gravel was the older of the two ; and 



Thirdly, that the valley of the Somme was excavated to a depth of 

 40 or 50 feet since the deposition of the upper valley-gravel, and 

 previously to the deposition of the lower valley-gravel ; 



Fourthly, that both gravels were fossiliferous, and contained the 

 remains of man, or rather human implements, and bones of extinct 

 mammalia, the lower gravels having the greater number of species 

 of mollusca, the higher gravels containing the greater number of 

 flint implements ; 



* For the Proceedings at this Meeting see p. 1. 



