1863.] 



PRESTWICH MOULIN QT7IGNON. 



501 



and always fragmentary, whereas they are often not in the slightest 

 degree worn, and parts and the whole of entire skeletons are not 

 unfreqnently found with every bone in place. Fourthly, the small 

 delicate and fragile land- and freshwater-shells would have been 

 generally destroyed, whereas they frequently occur in a state of 

 perfect preservation, and, in the case of the bivalves, with the two 

 valves occasionally not separated. Fifthly, it would behove the sup- 

 porters of this view to show beds whence the remains of the extinct 

 Mammalia could have been derived, whereas none such exist in the 

 district. I will not occupy the time of the Society longer with other 

 objections, as the subject in other forms has been often discussed. 



Fig. 1. — Section of the Gravel-pit at Moulin Quignon. 



>13 ft. 



a. Brown sandy clay, with angular gravel. 



b. d, f. Ochreous gravel- seams. 



c. Yellow sand. 



e. Light-green sand. 



g. Light-grey sand. 

 h. The " Black Band." 

 i. Chalk. 



Fig. 2. — Section of the Gravel-pit at St. Acheul. 



| >22 ft. 6 in. 



'^fe^^N^-^^:':^^..^.'!'- ?.£; 





a. Brick-earth, with angular gravel. 



b. Whitish sand and marl, with land 



and freshwater Shells. 



c. Light-coloured gravel. 



d. Ochreous gravel. 



e. White sand. 



/. Light-coloured gravel. 

 g. Chalk. 



On the other hand, we have at St. Acheul and Montiers fluviatile 

 Shells in the high-level gravels, and the same occur in the low-level 

 gravels at Menchecourt, and probably at Mautort. For these and 

 other reasons, into which I need not now enter, I have attributed 

 the formation of these beds to river-action continued through a long 

 period of time, and gradually excavating the valley from the level 



