480 PROCEEDINGS OF TKE GEOLOGICAL SOCIETY. [JunO 3, 



be no doubt of tbe correctness of Dr. llantell's later conclusion, as 

 clays and stales of the Wealden series are frequently found overlying 

 such conglomerates. The occurrence of flint-like pebbles at Piche- 

 vert, near ITarquise, led Dr. Pitton to think the beds there were of 

 comparatively recent date, derived from the waste of Wealden beds, 

 but intermixed with flints from the chalk. The mode of occurrence 

 of these pebble-beds in the Boulonnais is such as is very likely to mis- 

 lead an observer as to their true age, particularly if unacquainted 

 with the details of our English NYealden beds. They are mostly 

 found capping the hills, and are not overlain by other beds; at 

 Desvres, however, I noticed pebbles cemented into a conglomerate ; 

 here the section is low down the hill, and the whole series is capped 

 by Lower Grreensand. At Samer, also, pebbles occur in the "Wealden 

 beds. 



Yery few fossils occur in the Wealden beds of the Boulonnais. 

 Br. Fitton mentions Jlelanojms or Paludina from near Wimereux, 

 associated with a shell resembling Astarte. The fossils may have come 

 from the ferruginous sands ; but neither their identification nor 

 mode of occurrence seems very certain. M. Rigaux mentions Unio 

 from Equihen and Cydas or Cyrena from Eupembert. To this last 

 locality I was obligingly taken by M. Rigaux ; the fossils are very 

 plentiful in the ironstone, but occur mostly as casts, which Pro- 

 fessor Morris believes to be those of Cyrence. M. Pellat has also 

 found Cyrena at Equihen. 



The Wealden ironstone of the Boulonnais is largely worked for 

 smelting, over the central and south-eastern district mostly by 

 open quarries, in the north chiefly by shafts. There are large 

 blast-fmTiaces at Marquise, and at Outreau, near Boulogne. At 

 Marquise, according to M. S. Jordan *, the ironstone is mixed with 

 ore from Africa, chalk and other limestones of the district being 

 used for flux ; at Outreau the native ore is mixed with Cumberland 

 haematite. An analysis of Boulonnais Wealden ore gave 49-14 per 

 cent, of peroxide t ( = 34-39 per cent, of iron). Some account of the 

 smelting of this ore and of comparisons with other works in the north 

 of France is given in a paper by M. Leducq, read at the Society of 

 Agriculture of Boulogne in 1834 J. These furnaces are all of recent 

 origin ; no mention is made in Rozet's Memoir (1828) of the ore 

 being worked, nor in Bertrand's ' Histoii'e de Boulogne' (1829). M. 

 Henry, in 1804§, alluding to the great quantity of iron-ore in the 

 district, stated that the only obstacle to smelting it was want of fuel. 

 Coke is now chiefly got from Belgian coal. 



The iron-ores of our English Wealden have been worked from the 

 Roman times downwards. In the 17th century this was the chief 

 iron-producing district of England ; for out of 800 " milnes for the 



* Cuvper's ' Eevue de I'Exposition tTniverselle de 1867,' p. 416. 



t Ibid. p. 414. 



t ' Du Developpement de la Pi-oduction du Far dans le Nord-ouest de la 

 France, Proces Yerbal/ p. 183. 8vo, 1835. 



§ ' Essai historique . . . sur . . . Boulogne-sur-mer.' 4to, p. 225, (Printed 

 1804. published 1810.) 



