1868.] TOrLEY BAS-BOULONNAIS. 479 



against Portland limestone, the latter rising from beneath the Wealden 

 at the north end of the cutting. 



Capping Mont Lambert there is ferruginous sandstone with large 

 pebbles. I presume this likewise is Wealden, but could find no clear 

 section. The hills north and north-west of this are capped by 

 Wealden beds, which are in many places worked for ironstone. The 

 sections at Rupembert are of interest, as the ironstone there contains 

 casts of fossils (Cyrence). 



Where, as in the neighbourhood of Boulogne, the Wealden beds 

 rest on Portland, it is difiicult, in some cases, to divide them, as the 

 following section from a quarry north of Napoleon's Column will 

 show : — 



1 . Sand, and clayey sand, 4 feet. 



2. Bluish and mould clay, 4 to 6 feet. 



3. Irregular beds of sandstone and ironstone, 1 to 2 feet. 



4. Clay, bluish above, yellowish below, with lignites at the bottom, 



about 6 feet. 



5. Sandstones, soft above, hard below, 4 feet. 



6. Grreenish sand, 1 foot. 



7. Hard sandstone, with veins of carbonate of lime, 4 feet. 



The upper beds here are certainly Wealden, and the lower certainly 

 Portland. Perhaps 1, 2, 3 belong to the former, 5, 6, 7 to the 

 latter, and 4 to a bed of doubtful character to be further mentioned 

 presently (see p. 481). 



Wealden beds are seen here and there along the coast north of 

 Boulogne, and everywhere on the inland heights ; but the sections 

 given above may suffice to show their general character. 



French geologists have long been in doubt as to the exact age of 

 these beds. By many they have been classed with the Lower Green- 

 sand (Rozet, d'Archiac, Delanoue, and Pitton in 1826). Gosselet 

 and Hebert would place them with the Gault, whilst Sauvage and 

 Hamy have described some outlying patches as Drift. By Conybeare 

 in 1822*, Pitton in 1839, and since then by Rigaux and PeUat, 

 these beds have been referred to the Wealden. 



In the loose pebble-beds at St. Etienne, which I have described, are 

 some fragments very like flints, and others greatly resembling chalk ; 

 from this circumstance Messrs. Sauvage and Hamy have been led to 

 class these with the Drift. Such chalky-looking pebbles are very 

 common in the conglomerates at the western part of the Weald, near 

 Cuckfield and Lindfield ; they are probably derived from the waste of 

 Portland beds. At Cuckfield these conglomerates form part of Dr. 

 Mantell's Tilgate beds, and contain the usual reptilian remains. So 

 much do some of the pebbles resemble chalk that Dr. ManteU, in 

 1822 1, described these beds as " diluvium." In subsequent descrip- 

 tions of the district he omitted any mention of chalk pebbles, and 

 included the beds in question in the Wealden formation. There can 



* ' Outlines,' p. 155. The Hastings sands were tlien called " Iron Sands," 

 and their freshwater origin was not then recognized. This brief reference by Mr. 

 Conybeare to the Boulonnais ferruginous sands is the earliest geological notice 

 I have been able to find. It is interesting to note that his supposition as to their 

 age is the correct one. 



t Fossils of the South Downs, p. 39. 

 VOL. XXIV. PART I. 2Jj 



