906 



J. PRESTWICH ON" THE RANGE OE THE LOWER 



Pigs. 1 and 2. — Sections of Borings at Auchy-au-Bois, near Litters 

 (Dept. du Pas-de-Calais). 



Pig. 1 (No. 16). 



feet. 



m 



±£ 



X 



j i 



1 i 





o. Gravel. 



c. Chalk. 



(?. Tourtia. 



n. Devonian strata. 



Pig. 2 (No. 15). 



feet. 



557 



Z. Carboniferous strata. 

 cm. Coal-measures. 

 o. Coal-seam. 



Pig. 3. — Section across the Auchy-au-Bois Coal-field. 



c. Chalk. 

 n. Devonian. 

 /. Lower Carboniferous strata. 



cm. Coal-measures. 

 Lm. Carboniferous Limestone. 



