FERRUGINOUS SANDS AND GRIT WITH PLANTS. 
239 
parts of a connected series. In the absence of clear sections and junctions, and 
unprovided with any fossil evidences, we continued, therefore, to remain in doubt 
concerning these upper siliceous grits of Moscow, when we received a letter from 
Mr. Frears, who, in sending us drawings of fossil plants recently found in them, has 
happily enabled us to come to a distinct conclusion respecting these hitherto ambi- 
guous strata. Before we advert in greater detail to these plants, we must say a few 
words on the position and structure of the rock in which they have been discovered. 
As the Jura shales and sands which have been described, occur in depressions 
of the carboniferous limestone (woodcut, p. 235), and occasionally rise to certain 
heights upon the banks of the Moskwa ; so are they conformably surmounted by 
the siliceous sandstones and grits in question, which occupy the plateaux and 
summits of the country, where they are not covered with drift and detritus. For 
the most part they are ferruginous sandstones, occasionally containing green grains 
and somewhat earthy, but in their lower parts they exhibit large subcon cretionaiy 
masses of hard siliceous grit, usually of a white colour, which are extracted 
for building purposes and also for millstones, and form a regular article of export 
from Moscow to distant parts of Russia 1 . On the high grounds at Celo Nikilof- 
skaya, between Bronnitzi and Miatchkova, considerably to the south of Moscow, 
we examined quarries opened out from beneath yellow, white and reddish-brown 
drift, in which the upper beds of this rock consisted of greenish argillaceous sand, 
the central of ferruginous sandstone with ironstone concretions, and the lower of 
the compact white grit in question. 
The best sections, however, are seen in ascending the Moskwa for a few versts 
above the metropolis. We have already described the manner in which the fossili- 
ferous Jura shales and calcareous grits and sands are exposed at Koroshovo, on 
the left bank of that stream. They are there covered by the sands and grits which 
we are considering, but the bank being low and much eroded, the chief visible 
remnants of the overlying mass are hard blocks of siliceous grit, which, owing to 
their isolated and weathered aspect, appear at first sight to be boulders. But their 
true relations are observed by passing to the opposite and higher hank of the river. 
It is in this plateau, and near the hamlet of Tatarova, that the most extensive 
quarries have been laid open in the overlying sandstone, parts of which are iden- 
tical with the blocks at Koroshovo. The escarpment there presents to the river 
valley a section, in which 30 to 40 feet of sandstone have been cut into, surmounted 
i We met with the Moscow millstones at Nijny Novogorod, and even at Ustiug-veliki, 
2 I 2 
