1868.] TOPLEY BAS-BOULONNAIS. 477 



In the neighbourhood of Ferques, M. Delanoiie has described 

 these beds *. I quote the following from his paper. The ironstones 

 raised here are, he says, " sometimes superficial, and therefore hy- 

 drated ores, peroxidized and concretionary, with mottled clays and 



sands, and sometimes carbonates and sulphide of iron in 



the midst of bituminous clays. Wherever atmospheric influence has 

 made itself felt, in former times or now, the sulphuric and carbonic 

 acids have been replaced by oxygen and water." 



In several cuttings of the new railway from Boulogne to Calais, 

 Wealden beds are seen lying irregularly on the Palajozoic beds, and 

 mostly let into the Limestone in deep pipes (see fig. 4). Some of 



Fig. 4. — Sli'etcli-section of Railway -cuttings near Elmc/Jien. 



8.W. Haut Banc Quarries. Elinghen Church. N.E. 



a, a, a. Carboniferous Limestone. c. Angular Flint- Gravel. 



b, b, b. Wealden Sands and Clajs in pipes. X X • Level of Eailway. 



them are of large size : in one a depth of 30 feet was seen ; and as 

 this was 20 feet wide at the bottom of the cutting, it must descend 

 considerably deeper. These pipes contain sand, brown and variously 

 coloured clays, ironstone, and pipe-clay, with vegetable remains. 

 The patch at Elinghen is, as shown by pits, like that in the railway- 

 cuttings. Although the Wealden beds have a fair thickness around 

 Elinghen, yet a mile or so to the north-east, at Caffiers-cutting, there 

 are none. Lower Greensand here resting immediately upon Palaeo- 

 zoic beds ; and the Greensand itself is reduced to a thickness of a few 

 feet. The same is the case in a road- cutting west of the Bois de 

 Fiennes. The section here, already noticed, is less than a mile from 

 Elinghen. 



The high ground north-east of Bournouville is occupied by Wealden 

 beds. What little is shown here is mostly sand and a loose con- 

 glomerate of qaartz pebbles, partly cemented by ii'on. Some pits 

 show small pebbles with a whitish sandy clay, roughly bedded. 



Near Desvres, in the Haute Foret, is a large pit in Wealden beds, 

 showing from above downwards : — 



1 . Clay and loamy wash. 



2. Brown and whitish clay. 



3. Blue clay. 



4. Blue sandy clay (with lignite). 



5. Ironstone. 



The beds here, as usual, are very irregular. Another part of the 

 same pit showed coarse sand and pebbles, cemented by iron into a 

 brecciated conglomerate. These Wealden beds seem to go some way 

 up the hiU ; but towards the top is coarse sand of a lighter colour, 



*Bull. Soc. Geol. France, ser. 2. torn. ix. 1852, p. 403. 



