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THE GEOLOGIST. 



The great value of Mr. Prestwich's paper is in the minute details of the 

 sections and geographical areas of distribution of the flint implement beds at 

 Amiens, Abbeville, and Hoxne. The sections at Abbeville and Amiens are 

 first accurately described. 



Map of the Amiens' District. 



" Abbeville and Amiens are both situated in the valley of tne Somme, the 

 first at a distance of about fourteen miles, and the second of forty-one miles, 

 from the sea. The surrounding district consists of gently undulating elevated 

 plains of chalk, capped here and there by outliers of tertiary strata, and else- 

 where partly bare and partly covered by a few feet of fine light red or yellow 

 loam and clay, in places mixed with angular fragments of flints. The river 

 valleys are narrow, often exhibit on their flanks thick deposits of loam and 

 gravel, while the middle is usually a flat level of marsh and peat overlyiug 

 gravel. The loam, brick-earth, or loess, forms a very marked feature in this 

 usually bare chalk district, being principally accumulated in thick irregular 

 and local masses on the sides and flanks of the valleys. This is especially the 

 case for some distance both above and below Amiens, as well as up the greater 

 number of the lateral valleys. It extends to various elevations. A Tbed of 

 gravel also spreads over some of the lower hills flanking the valley of the 

 Somme. For full particulars of the geology of the district, I beg, however, 

 to refer to the works of M. Buteux and Dr. Ravin. 



" The fall of the Somme valley is very gradual, its elevation at Abbeville 

 above the level of mean tide of the sea being eighteen feet, at Amiens sixty 

 feet. Between these towns the mean width of the valley, which varies but 

 little, is rather less than a mile. The hills rise gradually to heights generally 

 of from two hundred to four hundred feet, and nowhere exceed six hundred to 

 six hundred and fifty feet above the sea-level, and that more in the interior of 

 the department. The pits in which the flint implements have hitherto been 

 observed are all in or near the main valley of the Somme. 



" Abbeville. — According to M. Boucher de Perthes, the principal localities 

 where flint implements have been found are, the village of Menchecourt, a 

 suburb at the foot of the hill on the north-west side of Abbeville, the town of 



