AUSTEN ON THE BOULONNAIS. 235 



partings of red compact shale, and which is separated by a very 

 marked horizontal line from a lower one of thick-bedded compact 

 limestone : this sudden break or change in the condition of the Haut- 

 banc limestone has been noticed by M. Rozet. The lowest beds of 

 this group are quarried opposite the Chateau des Barreaux ; they are 

 somewhat darker than the middle portion, and admit of being worked 

 for ornamental and useful purposes. 



Organic remains are not common, or at least obviously so, through- 

 out either of the limestone groups here noticed ; yet in beds of the 

 Napoleon marble, and which has usually been described as altogether 

 unfossiliferous, it will be found that where the limestone has been 

 decomposed at the junction with the sands of the oolite, every flake 

 struck off in the plane of the bedding presents beautiful surfaces of 

 Chonetes and Sti-opJiomena, of which it is not possible to detect a 

 trace in the more crystalline mass. As an exception to the general 

 rule respecting the indistinctness of the fossils of the upper limestone, 

 there is a remarkable bed, about 2 feet thick, subordinate to the 

 band of Napoleon marble, which is entirely composed of Terebratula 

 elongata and one or two other forms. 



The following list of species from the upper limestones, as well as 

 every other contained in this memoir, has been drawn up by Mr. D. 

 Sharpe : it will be readily seen to what extent he has added to our 

 knowledge of the distribution of forms, and thereby given a value to the 

 present communication which it would not otherwise have had :— 



Terebratula elongata, ScMoth. Chonetes papilionaceus, Phillips. 



Spirifer glaber. Strophomena crenistria, Phillips. 



Productus Martini. Euomplialus pentangulatus. 



auritus. Natica antiqua, Goldf. 



undatus. Loxonema sulculosa. 



scabriculus. 



The limestone of Haut-banc contains — 



Lithostrotion. Productus comoides. 

 Productus auritus. Terebratula hastata. 

 antiquatus. 



Below the hamlet of Basse Normandie there is another considerable 

 mass of limestone, on either side of the stream of which neither the 

 age nor relations were ascertained by the geologists at the Boulogne 

 Meeting. At its eastern limit this limestone dips E., and does so 

 for a considerable portion of its mass ; it then arches over, and on 

 the side near the road from Blecquenecque to Rinxent dips W. or 

 S. W. In this portion dolomitic beds like those of the upper quarries 

 of Haut-banc occur ; the uppermost beds in this direction consist of 

 compact limestone with seams of chert, apparently passing into 

 shales. I therefore consider it as belonging to the Haut-banc group 

 of limestone. 



In the Hardinghen district the carboniferous group is much less 

 clearly exhibited. On the N. the Haut-banc limestone may be seen 

 for a short space in the Bois de Fiennes striking N.W. & S.E. nearly, 

 and dipping S.W. ; it then passes beneath the coal-field of Locquin- 

 ghen. The limestone which occurs immediately at the back of the 



VOL. IX. — PART I. R 



