A. J. Jakes-Browne — Boring through Chalk near Dieppe. 27 



The only specimen seen by Mons. Dollfus was one of a hard 

 chalk with fragments of Inoceramiis labialus; this he is inclined to 

 refer to the Turonian, but as the species also occurs in the highest 

 part of our Lower Chalk, I am disposed to think the base of the 

 Middle Chalk was traversed at 88-30 metres, i.e. 289^ feet. He 

 agrees with me in regarding the " green sandy clay " as the base 

 of the Cenomanian, which thus has a thickness of 229^ feet. 



The only important difference between the account furnished to 

 me and that communicated to Mons. Dollfus is in regard to the 

 lowest beds, for it seems that the boring passed through the grey 

 sand at 209-45 metres and entered a black sandy clay. It is 

 impossible to suppose the Vectian sands to be only 10 feet thick 

 below Dieppe, nor is it likely that a thick bed of black sandy clay 

 should occur in them ; consequently M. Dollfus believes that both 

 the sand and the clay belong to the Gault. 



In support of this view he sends the particulars of another boring 

 recently made at the Chateau d'Eu in the valley of the Bresle, 

 about 16 miles north-east of Dieppe. Samples and fossils from this 

 boring were seen and determined by M. Munier-Chalmas, and there 

 is consequently a much greater certainty about the horizons. The 

 followino; is a translation : — 



Alluvia of the valley of the Bresle 



' AVhite chalk with ithync. Cxricri 



Firm white chalk with some fiiuts 



Chalk without tliuts, some hard lumps ... 



Chalk without tliuts, very sticky 



Grey chalk 



Soft yellow chalk 



Grey and white chalk, in hard and softer heds 

 \^ alternating-, Itioc. hibiafiis ... 



^ ( Grey and blue argillaceous chalk, viiilx Bclcmintes 

 S Soft white chalk, with HoJaslcr ... 

 ^ J Grey compact chalk 

 § j Marly o;rey chalk ... 

 g Greeuish-grey sandy chalk 

 O 1^ Green clayey glauconitic chalk ... 

 ( Black clay with Iiioccrami<s 



Greenish quartzose sand ... 



Black and green saudy clay 



Pure green sand ... 



Greeu and black clay, with Ai]iino)i'itcs aiirltiin 

 ■{ and Am. sp/ciideiis ... 



Greenish-grey sand and sandstone 



Bed of greenish sandstone 



Greeu sand with large grains of quartz ... 



Black sandy clay ... 

 i^ Green quartzose sand (not pierced) 



This boring is very interesting in sever 

 place the base of the Turonian is clearl}' fixed 

 the base of tlie Cenomanian at 139 m. This gives a thickness of 

 68-54 m. (=2:^4-8 feet) for the Cenomanian or Lower Chalk, thus 

 eorroborating my interpretation of the Dieppe boring. In the next 

 place the curious alternations of black clay and green sand, which 



