KVIDENCKS OF THE GEOLOGICAL AGE, ETC. 
405 
those avt.iclos. Figures 1 and 2 ropvoscnt in outline on a scale of one sixlli 
tiie two principal forms of the larger kinds of flint imiilenicints, such as arc 
found in France, England, and elsewhere, wherever such remains have been 
Pig. 1.— Large Flint Implement fi-om St. 
Achenl. Collected by M. Boucher tie 
Perthes. 
Fig. 2. — Large Flint Implement, jirobably 
javelin head, found 1)y Mr. Flower. Nat. 
Size : 8 inches by 3| inches. 
found. Fig. 2 is the decisive implement as to the correctness of the position of 
the instrnmeuts in gravels of really geological age, found by Mr. J. W. Flower, 
of Croydon, at St. Acheul, near Amiens, in the presence of Mr. Prestwich and 
other geologists, in June of last year. This specimen was extracted from a 
seam of ochreous gravel (2A of section below) twenty feet below the surface. 
The section of the geological deposits at that place as given by Mr. Prestwich 
(in descending order) are 
Average 
thickness. 
1. Brown brick-earth (many old tombs and some coins) 
with an irregular bed of flint-gravel. No organic re- 
mains. B'wmonal plane bettceen 1 and 2 uneven and very 
often indented 10 to 15 feet. 
2«. Whitish marl and sand, with small chalk-debris. 
Land and freshwater shells (Lymnea, Succ'mea, Helix, 
Bithynia, Planorbis, Pupa, Pisidium, and Ancyliis, all of 
recent species) are common, and mammalian bones and 
teeth are occasionally found 2 to 8 feet. 
21. Coarse sub-angular flint-gravel, white with irregular 
ochreous and ferruginous seams, with tertiary flint peb- 
bles and small sandstone-blocks. Remains of shells 
as above, in patches of sand. Teeth and bones of ele- 
