South-ivesl and North of France , and South of Germany . 139 
wald principally of newer unstratified rocks, as sienite, granite, 
porphyry ; and hills on both sides of these ranges seem’ to 
consist of the two great red arenaceous deposits of the Vosges, 
which are not, however, separated by the magnesian limestone 
(zechstein) ; yet, on the east of the Black Forest, the porphyries 
have given rise also to some porphyritic detritus, which lies un- 
der the coarse red conglomerate, which cannot be confounded 
with any other, by an observer acquainted with the characters 
of the old red sandstone, the todliegende, or newer red sand- 
stone, and the red marl. 
On the west of these chains, the red marl has been much 
destroyed, and has given rise to the valley of the Bhine, inclosed 
between two precipitous ranges of rock ; but on the east it is 
still entire, and forms an extensive tract of country from these 
to the German Jura chain, (See Keferstein’s Map). It abounds 
in Wirtemberg, and its marls present the same appearances as 
elsewhere. They contain gypsum, salt-deposits, beds of lime- 
stone, and traces of vegetables. 
We shall now trace the shell limestone, and shew that by 
some observers it has been confounded with the Zechstein. 
It may afford matter of surprise that I should contradict the 
opinion of so many celebrated men, but the fact is clear, and the 
confusion has arisen merely from mistake regarding the geognos- 
tical position of the Jura limestone. In Swabia, geologists not 
finding the zechstein, and yet being anxious to recognise a depo- 
sit so well known in the north, had naturally, from their not being 
acquainted with the shell limestone (muschelkalk), taken this de- 
posit for the zechstein, because it lies above what they rightly con- 
sider as the todliegende. This base admitted, they naturally be- 
lieved that the salt-deposit was placed between their zechstein and 
todliegende, and this salt they rendered subordinate to the zech- 
stein or alpine limestone of Friesleben. Further, they then 
naturally called the Jura limestone the Shell limestone, (muschel- 
kalk), and the quadersandstein the Bed marl. But when it is 
once acknowledged, what it is impossible to deny, that their 
shell limestone (muschelkalk) is not the zechstein, but in reality 
the second flcetz limestone, it then naturally follows that, as 
every where else, the salt-deposit lies under the great mass 
of that formation, and alternates with the lower part of it. 
