TYLOR AMIENS GRAVEL. 



Ill 



These joints are now in many cases fissures two or three inches 

 wide, and extending to a considerable depth ; but they are filled up 

 with a fine brown loess, which seems as if injected into them ; for I 

 observed in one or two cases that a vein of two or three inches thick 

 had entered a horizontal joint, and passed along that in a horizontal 

 direction, thinning out to only half an inch. I give a sketch of this 

 chalk-quarry. This system of joints would very much facilitate the 



Fig. 2. — Section exposed in a Chanc-qitarrtj near Gidgencourt. 



formation, or rather the separation, of the chalk into rectangular 

 and imperfect spheroids, such as are seen in the quarries behind St. 

 Acheul and Longuean, where some decomposing agency has acted upon 

 the chalk itself with considerable efiect. 



In the drawing (fig. 3) made of the condition of the surface of the 



Fig. 3. — Section along the St. Acheul and Longueau Road. 



chalk (and to a depth of 20 feet) along the Saint-Acheul and Longueau 

 road, running east and west, I found the sandpipes in the chalk very 

 close together, and filled with brown loess and gravel. There are 

 some large pipes in the eastern escarpment in M. Dailli's garden, 

 close to the road ; but they decrease towards Cagny on the escarpment 

 of chalk trending southwards there exposed, and also in the escarp- 

 ment of chalk trending northwards. (See fig. 4.) I did not observe any 



Fig. 4. — Section in M. Dailli's Garden showing 



Chalk. 



decomposed chalk in the railway- cutting or quarry between Longueau 

 and La Neuville, nor at the ballast-pit in the chalk near La Neuville 

 at the railway workshops, Amiens. The surface of the chalk, how- 

 ever, is irregular, and covered with gravel, but without deep pipes. 



