230 ME. J. W. D. ROBINSON ON [vol. lxxvi,, 



Grivetian. 



Godwin-Austen describes 1 as the lowest beds a limestone (Lime- 

 stone of La Cedule) with underlying black shales; from the 

 former he obtained fossils in a quarry near La Cedule. Neither of 

 these has since been seen. The fossils are the same as those that 

 occur in the overlying Blacourt Limestone, and a reference to- 

 the map shows that a wedge of this limestone extends close to- 

 the north-west of La Cedule. There is no doubt that the quarry 

 described was a small one, now overgrown, in this wedge. The 

 shales probably belonged to the Gault. 



Lower Grivetian: Caffiers Conglomerate. — The lowest 

 bed visible is a red conglomerate, consisting of big partly-rounded 

 pebbles, embedded in clay or in a soft shale ; in the upper part the 

 pebbles are absent. 



No fossils have been found. The beds may be seen in the 

 railway-cutting south of Carriers, and traced across the countiy b> 

 Blacourt by the colour imparted to the soil. There are also small 

 exposures in the lanes north-east of La Cedule. 



Caffiers Sandstone. — This can now only be seen in an old 

 quarry north of Banc Noir Quarry, in the fields on the opposite side 

 of the railway, in a path north-west of La Cedule, and in an old 

 quarry by the road at Bainghen. Formerly a very complete 

 section must have been visible in the railway-cutting as E. Rigaux 2 

 gives the section set out below. The exposures now seen are of 

 a green fine-grained sandstone. 



Some remains of plants have been found in these beds, and have 

 been referred to Mliodea condrusorum and Le/pidodendron. 



Feet inches. 



f(a) Greenish, yellowish, and red shales 32 10 



(6) Sandstone 2 6 



(c ) Nodular limestone 4 11 



(c7) Fine-grained, greenish-grey, fissile sand- 

 stone 13 1 



■{ (e) Shales 4 11 



(/) Sandstone as (d) 11 5 



(g) Red and green shales 16 4 



(7?) Sandstone 11 5. 



(i) Grey shales 4 11 



(__(/) Shaly sandstone and micaceous shales . 16 4 



Caffiers ( (fr) Red shales 45 11 



Conglomerate. ^ (Z) Red conglomerate 29 5 



Middle and Upper Givetian: Blacourt Limestone. — 

 This is a dark-grey to black massive limestone, about 840 feet thick. 

 About 570 feet from the base the beds in places appear shaly, 

 owing to strike-faulting. At the top the beds are shaly, but still 

 calcareous. From the fossils the upper jjart is referred to the 



1 Q. J. G. S. vol. ix (1853) p. 242. 



2 ' Notice Geologique sur le Bas-Boulonnais ' 1892, pp. 7-8. 



Caffiers 

 Sandstone. 



