178 GEOGNOSY AND GEOLOGY. 
then the upper green sand, 6, differing from the sand masses of the lower 
green sand by the presence of a much greater number of green particles. 
It contains many silicious and not very compact concretions called cherts. 
Next come the chalk marl, 7, the Grew-chalk limestones, 8, and the white 
chalk, 9. 
The upper formation of the white chalk assumes quite a different 
character in the Pyrenees, in the Alps, and in the Apennines. Conglo- 
meratic slaty sandstones, resembling grauwacke, mixed with mica, occur 
here. They are known by the name of Macigno in Italy, in Switzerland 
as Flysch and Vienna sandstone, and contain many vegetable remains, 
especially of Fucoids, for which reason they have been called fucoidal 
sandstones. Hippurites occur in the limestones, but not in the northerr 
chalk rocks ; in the southern they are, however, found. 
In the Apennines, a limestone and slate mass underlies, and contains 
large numbers of Spatangus retusus. Upon this rests the hippurite 
limestone, characterized by Hippurites, Radiolites, &c. Then follows the 
nummulite sandstone entirely filled with Nummulites ; and alas the fucoidal 
slate, Flysch or Vienna sandstone. 
Recent investigations of the cretaceous formation in France have given 
rise to the following division of the strata : 
On the neocomien formation lies the lower chalk, the terrain aptien, 
embraced by the upper strata of the latter, and separated from it by its 
paleeontological characters. 
Upon this is the terrain albien, consisting of the lower greensand and the 
gault, characterized by Inoceramus concentricus and Trigonia aliformis. 
Then the chloritic chalk or the terrain turonien. It includes the upper 
green sand, the limestones of the upper formations of the first group (the 
crate tuffeau) and the chalk marl, and is decidedly characterized by the 
presence of Hippurites and Baculites. The senonian strata (terrain 
senonien) close the series, being composed of the true white chalk of both 
formations. ; 
The stratification of the individual members of the cretaceous formation 
is much diversified: in the chalk rock it is very intricate, while in the 
quadersandstein it is exceedingly regular; double rectangular cleavage 
traverses it in such a manner as to produce cubiform blocks. The thickness 
of the cretaceous often exceeds 1000 feet. It sometimes forms 
whole mountains, whose external appearance is affected greatly by the 
particular member which is present. When the softer varieties predominate, 
they possess a gently rounded exterior; the chalk rock inclines to the 
formation of a spherical surface, and the quadersandstone to that of 
picturesque rocks. The chalk itself forms high cliffs, especially on the 
coasts. | 
The soil produced by the weathering of the quadersandstone is poor and 
sandy ; that resulting from the marl very warm, on account of the amount 
of lime ; for this reason it is well adapted to the growth of the vine. The 
springs are inconsiderable in number, and feeble in character; some, 
however, are exceptions in being quite copious: a few are saline. 
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