South-west and North of France , and South of Germany. 143 
Upon the old red sandstone rests the great alpine calcareous 
tract , which belongs to the zechstein or magnesian limestone ; 
it is in great part a magnesian limestone, which presents some 
varieties of rocks, one of which is rather compact, another 
somewhat granular, while another is fetid, and some, particu- 
larly those in the upper part of the formation, are porous, or 
present the structure of the rauchwacke (Eisenertz.) In its 
lower parts there are vast deposits of lead and zinc, in the 
form of small veins ; bitumen is found here and there in it ; 
in some places mercury has been collected, which could only 
come from some bituminous part of this formation, and here 
and there are found columns of porphyry (Hindelong, Geis- 
alp). This grey, or yellowish, or whitish limestone, forms very 
high hills of at least 7000 or 9000 feet, and its masses very 
rarely show any traces of stratification. Petrifactions are ex- 
ceedingly rare in it. It is the Hochgebirgskalk of Escher and 
Uttinger, and a part of the alpine limestone of Humboldt, Freis- 
leben, De Buch, &c. It is impossible to confound it with any other 
limestone deposit, for it has not the slaty structure of the transi- 
tion limestone, nor the petrifactions of the shell limestone (mus- 
chelkalk), and, besides, it lies everywhere under the variegated 
sandstone and salt-formation. This last formation presents, in 
the Alps, as elsewhere, two masses, an arenaceous and a marly. 
The first is composed of alternations of greywacke-like micaceous 
sandstone, seldom very coarse, with marls which are of a greyish, 
brownish, or yellowish colour ; in short, not red like the varie- 
gated sandstone of Germany, because in the northern part of the 
Alps there have been no porphyries, to give them the necessary 
supply of hydrated oxide of iron. These rocks are placed above, 
and sometimes also below the marly masses, which consist of al- 
ternations of various marls, more or less indurated, and of a 
brown, reddish-brown, blackish, greyish, or greenish colour - 
they contain gypsum and rock salt. Petrifactions are not 
seen in this formation, but there are many vegetable remains, 
often of marine plants (Kahlenberg). This formation, which is 
distinctly stratified in thin layers, lies between the magnesian 
limestone and the shell limestone (muschelkalk) ; and, as else- 
where, the upper part of it often alternates with indurated marl 
