CHAP. IX. FLINT TOOLS NEAR BEDFORD. 165 



valley was scooped out. It is a portion of the gi-eat marine 

 glacial drift of the midland counties of England, and contains 

 blocks, some of large size, not only of the oolite of the neigh- 

 borhood, but of chalk and other rocks transported from still 

 greater distances, such as syenite, basalt, quartz, and new red 

 sandstone. These erratic blocks of foreign origin are often 

 polished and striated, having undergone what is called glacia- 

 tion, of which more will be said by-and-by. Blocks of the 

 same mineral character, imbedded at Biddenham in the 

 gravel No. 3, have lost all signs of this striation by the fric- 

 tion to which they were subjected in the old river-bed. 



The great width of the valley of the Ouse, which is some- 

 times two miles, has not been expressed in the diagram. It 

 may have been shaped out by the joint action of the river 

 and the tides when this part of England was emerging from 

 the waters of the glacial sea, the boulder clay being first cut 

 through, and then an equal thickness of underlying oolite. 

 After this denudation, which may have accompanied the 

 emergence of the land, the country was inhabited by the 

 primitive people who fashioned the flint tools. The old 

 river, aided perhaps by the continued upheaval of the whole 

 country, or by oscillations in its level, went on widening and 

 deepening the valley, often shifting its channel, until at 

 length a broad area was covered by a succession of the ear- 

 liest and latest deposits, which may have corresponded in 

 age to the higher and lower gravels of the valley of the 

 Somme, already described, p. 130. Mr. Prestwich has hinted 

 that perhaps the drift of Biddenham, which is thirty feet 

 above the present level of the Ouse, and contains bones of 

 Elephas primigenms, and the shells above alluded to, may be 

 a higher-level alluvium; and the gravel on which the town 

 of Bedford is built, which is at an inferior level relatively to 

 the Ouse, may be a lower deposit, and consequently newer. 

 But we have scarcely as yet sufficient data to enable us to 



