Part III. Sect. iii. § 2.] CRETACEOUS. 825 
north of France and Belgium the Cretaceous system is underlaid by 
certain clays, sands, and other deposits belonging toa Continental period 
of older date than the submergence of that region beneath the sea in 
which were deposited the uppermost Neocomian beds. These scattered 
Continental deposits have been grouped under the name of Aachenian.! 
On the coast the Folkestone type of Neocomian beds is well seen 
between Boulogne and Calais. 
Gaulé or Albian.?—This characteristic and easily-traced subdivision of 
the Cretaceous series appears on the coast opposite to Folkestone with 
the same lithological and palzontological features as on the English side 
of the Channel. The pyritous clays sweep round the northern and 
eastern margin of the great Paris basin, and appear likewise on the west 
near Havre. They have also been found in deep wells around Paris. 
They contain the following subdivisions in descending order : 
3. Zone of Ammonites inflatus—Glauconitic clay of Sancerre, Ochre of Puisaye, 
Marls of Larrivour, “ gaize”’ (a porous sandstone slightly impregnated with 
silica soluble in alkali) of the Argonne, upper clay of Wissant, &c. It 
has yielded 141 species of fossils, among which are Ammonites inflatus, 
A. splendens, A. auritus, Nautilus radiatus, Hamites intermedius, Natica 
gaultina, Rostellaria carinata, Cardita tenuicosta, Inoceramus sulcatus, 
Peeten raulinianus, Janira quinquecostata, Plicatula pectinoides, Ostrea 
canaliculata, Terebratula dutempleana, Kingena lima. 
2. Zone of Ammonites interruptus, consisting of dark clays with nacreous 
shells, sands, and sandstone. Ammonites interruptus, A. splendens, A. lautus, 
A. denarius, Hamites rotundatus, Natica gaultina, Cardita tenuicosta, Ino- 
ceramus concentricus, Plicatula pectinoides, &c. 
1. Zone of Ammonites mammillaris—green sand sometimes containing phosphatie 
nodules—Ammonites mammillaris, A. raulinianus, A. Beudanti, Natica 
gaultina, Pteroceras bicarinatum, Inoceramus Salomoni, Plicatula radiola, 
Rhynchonella gibbsiana, &e. 
The Upper Cretaceous rocks of France have been the subject of prolonged 
and detailed study by the geologists of that country. The northern 
tracts form part of the Anglo-Parisian basin, in which the upper Creta- 
ceous rocks of Belgium and England were laid down. The same paleon- 
tological characters, and even in great measure the same lithological 
composition, prevail over the whole of that wide area, which belongs to 
the northern Cretaceous province of Europe. Apparently only during 
the early part of the Cenomanian period, that of the Rouen chalk, did 
the Anglo-Parisian basin communicate with the wider waters to the 
south, which were bays or gulfs freely opening to the main Atlantic. In 
these tracts a notably distinct type of Cretaceous deposits was accumu- 
lated, which, being that of the main ocean, covers a much larger geo- 
graphical area and contains a much more widely diffused fauna than are 
presented by the more limited and isolated northern basin. There are 
few more striking contrasts between contemporaneously formed rocks in 
1 On the Aachenian deposits see Dumont, Terrains Crétacés et Tertiaires (edited by 
M. Mourlon, 1878), vol. i. pp. 11-52. 
2 See besides the works already cited, Barrois, Bull. Soc. Géol. France, 2e sér, iii. 
707; Ann. Soc. Géol. du Nord, ii. p. 1; Renevier, Bull. Soc. Géol. France, 2e sér. 
iii. 704. 
3 Notably by MM. Hébert, Toucas, Coquand, and Cornuel. As already stated con- 
siderable differences exist among French and Swiss geologists as to the nomenclature 
and the lines of demarcation between the upper Cretaceous formations, arising doubtless 
in great part from the varying aspect of the rocks themselves according to the region 
in which they are studied. I have followed mainly M, Hebert. 
