ae 
Reviews—A. de Lapparent—Carte géologique de la France. 229 
of the clay, that it is probably due to thermal origin; and cites the 
opinion of M. Dumont, who attributed to a geyserian origin the 
Aachenien deposits of sand and clay in the Hainaut, and which are 
considered to belong to the Wealden of England and that of Bray 
(p. 53). The Middle Neocomian, from 15 to 25 yards in thickness, 
is formed of sands, or ferruginous grit, and of more or less black 
shaly clay ; marine remains are found in the sand (Cardium subhil- 
lanum, Pleuromya neocomiensis), and ferns (Lonechopteris Mantelli) in 
the clay, pointing somewhat to an estuarine origin. ‘To these 
succeed the Upper Neocomian of variegated clays (glaise panachée), 
from 15 to 25 métres, and which are largely worked for pottery. 
The Aptien, with Ost. aquila, d’Orb., succeeds; above which occurs the 
Albien, the lower part consisting of green sand from 20 to 40 métres 
thick; the upper, or Gault, of variable thickness (6 to 50 métres), and 
containing the usual characteristic fossils, Am. splendens, Inoc. sulcatus, 
I. concentricus, etc. Above the Gault is a deposit termed Gaize, 
about 40 métres thick, which may be considered as a passage 
between the Gault below and the Cenomanien above ; it is composed 
of clay-marl indurated by silica, the silica being partly in a gelatinous 
or soluble form (about 83 per cent.). The contained fossils are 
Am. rostratus, Sow., A. auritus, Sow., A. falcatus, Mant., Pecten 
elongatus, Sow., etc. Above the Gaize the Cretaceous deposits be- 
come more calcareous, and consist of the glauconitic and marly 
Chalk, and the nodular White Chalk. 
The Tertiary strata are not well represented, but traces of the 
Lower Eocene occur on two sides of the Bray, which attest its former 
extension over the region now elevated. A chapter is devoted to 
the clay with flints (argiles @ silew), which M. de Lapparent attri- 
butes to the chemical dissolution of the chalk; this clay varies in 
colour from brown to red according to the formation with which it 
is associated, and its age is referred to the end of the Tertiary period. 
The ancient and modern alluviums and turf-bogs are briefly described, 
and an interesting account of the variation of the Jurassic and 
Cretaceous strata, and their relation with those of the surrounding 
region, concludes the second part of the memoir. 
The elevation of the Bray, and the movements to which it has been 
subjected, forming the third part of the memoir, are treated in con- 
siderable detail, and full of suggestive remarks and observations on 
the various parts of the district examined by the author, including 
the determination of the age of the elevation (p. 149), and its relation 
to the different geological disturbances of other parts of France ' 
. 167). 
Phe Eien is a résumé of the third part: “The dislocation 
which has given rise to the Pays de Bray forms part of a series of 
1 Tn alluding to the researches of MM. Hebert and de Mercey on this district, 
M. de Lapparent does not mention the important paper by Dr. C. Barrois (Sur le 
Terrain Crétacé Supérieur), in which that author concludes,—that the axis of 
Kingsclere is the prolongation of the axis of Artois, the axis of Winchester that of 
the Bresle, and the axis of the Isle of Wight and of Purbeck that of the Pays de 
_ Bray. See Geox. Mac. Dec. II. Vol. III. p. 514. 
