228 Reviews—A. de Lapparent—Carte géologique de la France. 
divisions: 1. A plateau or terrace, the zone of villages. 2. An undu- 
lating surface, the zone of forests. 3. A ridge or crest forming Haut 
Bray, which attains an elevation of more than 600 feet. From this 
elevated zone, upon which some villages are situated, the sources of 
the Bethune, Seine, and Oise arise. The soil of the district is either 
marly, clayey or argillo-siliceous, so that a general argillaceous 
(boueuse) character prevails throughout the surface of the Bray.’ 
The second part treats of the geological formations and their 
characteristic fossils; for fuller details of the latter, the reader is 
referred to the work of M. Graves. 
The formations belong to the Jurassic, Cretaceous, and Tertiary 
strata. The lowest Jurassic stratum is the Upper Kimmeridge 
(which forms the highest part of the Haut Bray), consisting of lime- 
stones, clays, and lumachelle, more or less sandy, with Ostrea virgula, 
the two latter being generally separated by a band of compact litho- 
graphic limestone; at one point, however, near Louvicamp, a lower 
zone (the Ptérocérien or Astartien) has been observed. The total 
thickness of the Kimmeridge in the Pays de Bray is estimated at 
120 yards, or nearly double that assigned to it by M. Pellat in the 
Boulonnais. 
The Portlandian is divided into three stages. The Lower stage 
consists of glauconitic grits and marly limestone, with Anomia 
levigata, Sow., and Ost. catalaunica, Lor., corresponds to the Port- 
landian of the Barrois and of the Jura, and is considered to be the 
equivalent of the upper zone of Kimmeridge clay in England. The 
upper part is covered by a calcareous conglomerate of milky and 
dark quartz pebbles, which has a great resemblance to the con- 
glomerate at the base of the Portlandian in the Bas Boulonnais ; the 
thickness of this stage increases from 35 métres at Neufchatel to 
50 metres at Villembray. 
The Middle Portlandian, composed of blue marls with large 
Ammonites, is of moderate thickness, and is considered to be the 
exact equivalent of the Portlandian clays with Ost. expansa of the 
Boulonnais. 
The Upper Portlandian consists of ferruginous grits and sand, with 
Trigonia gibbosa, is of limited thickness (about 8 to 10 métres), and 
corresponds to the Portland stone and sand of England. It varies in 
composition in the northern, central, and southern parts of the 
district ; in the central area the fossils are frequently highly silicified. 
The grits and sands of the Upper Portlandian are succeeded by a 
formation with a lacustrine facies, which M. Graves long since 
recognized as the equivalent of the Neocomian group of the Haute 
Marne and of the Jura. The lower stage of white sands and re- 
fractory clays is, by its mineral character and the remains of ferns 
it contains, very analogous to the Weald-clay of England. The clay 
(glaise), an essential element of this stage, has been largely worked. 
M. de Lapparent considers, from the special nature and irregularity 
1 Tt is from this character that the name of the region is derived, for the word 
Bray comes from Braium, which, in the ancient language of Gaul, signifies Jowe, 
marecage, or heu hwmide. 
