64 GEOLOGICAL MEMOIRS. 
tain ridge, decidedly pot to their synchronous formation. If we 
now assume, with the greater number of geologists, that the trachyte 
belongs to the tertiary period, then the Schemnitz greenstone must 
also be tertiary, and the veins which traverse it are naturally still 
more recent, and, if the greenstone belongs to the older, will probably 
take their place in the middle tertiary period. 
The eastern basis of the greenstone mountains is covered with a 
breccia-like tufa of undetermined thickness, which passes gradually 
into the true greenstone, and is most appropriately named a green- 
stone-tufa. It contains, where arenaceous, numerous impressions of 
leaves of dicotyledons and also brown coal, which near the veins is 
changed into siliceous anthracite. This tufa is undoubtedly pene- 
trated by the more eastern veins, and since it cannot be more ancient 
than the greenstone, the veins that traverse it must also have been 
formed not earlier than the middle of the tertiary epoch. 
3. The basalt at Schemnitz is decidedly more recent than the tra- 
chyte, as at Kieshubel it is seen very distinctly penetrating this rock 
and enclosing numerous fragments of it ; but it appears to have been 
already in existence when the fissures of the Schemnitz vems were 
formed, since it imposes a limit to their further extension towards 
the east. In proceeding eastwards from the high gneiss ridge, the 
veins running parallel to it are successively crossed ; the last but one 
is found immediately in front of the basalt ; the last and most eastern, 
the so-called green vein, should, from its direction, either traverse the 
basalt or be traversed by it. But neither happens; the vein dis- 
appears at a considerable distance from the basalt and without reach- 
ing it, thus proving that there was a tendency to form more fissures 
further to the east, but that the compact basalt proved an msur- 
mountable obstacle, and hence must have already been in existence. 
This also shows that the formation of these fissures took place at least 
in the middle tertiary period. 
Though no one of these reasons by itself might have been sufficient 
to prove the comparatively recent origin of the Schemnitz veims, as 
they all depend on somewhat hypothetical suppositions ; still taking 
them altogether, and considering that they all agree in pointing to 
one and the same age, and that there is nothing which contradicts 
this view or leads to the supposition of a greater antiquity, the for- 
mation of these veins during the middle tertiary period may be con- 
sidered as well-established, however great the anomaly when compared 
with the date assigned to most other veins. [J. N.] 
On the Fossil Plants discovered on the UpPER Ruone. By O. HEER. 
[From Leonhard and Bronn’s Jahrbuch fiir 1848, p. 369.] 
THe author has collected many fossil plants im a very fine-grained 
bluish- grey marl which overlies the tertiary coal of the Upper Rhone. 
A similar but coarser-gramed marl is found under the beds, in which 
leaves of plants also occur, but far fewer in number and not so well 
preserved. It lies upon a coarse-grained sandstone, and a similar 
