MIDDLE CHALK—NORTH OF FRANCE. 
495 
B. The North-West of France. 
Passing across the central part of the Paris basin, which was 
part also of the central area of deposition, we shall notice some of 
the more western exposures of the Turonian Chalk. Excellent 
sections of this division are exhibited in the cliffs at Dieppe, Fecamp, 
and Etretat, and these have been described by E. Hebert between 
the years 1872 and 1876, but so far as I can learn no more 
recent study of them has been published. There are also good 
exposures at Rouen, Villequier, and other places in the valley of 
the Seine, which have been described bv Monsieur G-. Lennier and 
others. 
The following general account of the “ craie marneuse ” in the 
Department of the Seine Inferieur is translated from the legend 
of the Yvetot sheet of the Carte G-eologique Detaillee. “ The 
highest part consists of white marly chalk, firm and without flints, 
characterised by Terebratulina gracilis . Below come beds which 
are not quite so white, containing many layers of black flints, and 
characterised by Echinoconus subrotundus. At the base are beds 
of much harder chalk containing Inoceramus labiatus (=myti- 
loides), which never contain flints, and are employed for 
making lime.” From this it will be seen that the succession in 
this district corresponds very closely with that of Southern 
England. 
I cannot find, however, that much information has yet been 
published about the country round Evreux and along the valley 
of the Eure, while on the higher ground of the Department of the 
Eure the chalk is concealed beneath some thickness of Tertiaries 
and of “ clay with flints.” When the Turonian emerges again 
in the Departments of the Orne, Eure et Loire, and Sarthe it 
exhibits a very different facies, and for these areas we have 
descriptions by the late M. Gruillier, by MM. P. Bizet and A. de 
Grossouvre. 
At Rouen the Turonian zones of Inoceramus labiatus and Tere¬ 
bratulina gracilis are said to be about sixty metres (about 200 feet); 
and more than half of this thickness is shown in the large 
quarries at the base of Mont St. Catharine. The following 
is an abbreviated account of this section, as given by Mr. 
Lennier. * 
Metres. 
§» . ( Weathered chalk -.3 
S'sgS , Soft white chalk, with a few flints, Ter. gracilis - 12 
o ‘g «£ / Soft white chalk, with more numerous flints - - 8*50 
^ I Layer of nodules of hard chalk, green-coated, and 
( called “ caillasse ” by the workmen - - - *10 
*Bull. Soc. Geol. Norm., Yol. vi. p. 387. 
