28 GEOLOGICAL MEMOIRS. 
tains or in the vicinity of the transition rocks. Further, rolled masses 
of felspar (eurite) porphyry, near Badenweiler and Schonau with 
grey, near Lenzkirch with red felspar. These rocks are also found 
im situ in the vicinity of the transition formations. Gmeiss is not 
common among the fragments in the Schwarzwald transition rocks, 
probably because the conglomerates lie wholly in the region of the 
granites. 
We perceive from these facts that a portion of the granite, of the 
felspar porphyries, and of the gneiss, not to mention less remarkable 
rocks, already existed before the deposition of the transition forma- 
tions, and consequently belong to the oldest plutonic productions. 
2. Clay-slate and greywacke-slate occur very frequently among the 
rolled masses of the greywacke. This fact, together with the rela- 
tive position of the beds, proves that these rocks were among the 
most ancient neptunian formations of the Schwarzwald, and deposited 
before the great currents which formed the transition conglomerates. 
3. The geological relations of these transition strata furnish the 
clearest proofs, that after their deposition very important geolo- 
gical catastrophes have occurred in the Schwarzwald, remarkable 
outbursts of plutonic rocks forming whole hills and mountain chains. 
We find, for example, veins of granite and quartzose porphyry in the 
transition rocks. Very distinct granite veins occur on the Windgfall- 
Hoff near Lenzkirch and on the summit of the Spiesshorn at Bernau 
near St. Blasien; and the most beautiful vein of quartz porphyry is 
found in the clay-slate at Hof Bernau on the declivity of the Herzo- 
genhorn. In various places also large masses of granite or quartzose 
porphyry project amidst the transition strata; of the former, for in- 
stance, in the Spiesshorn and the Bildstem in the Aha valley; of the 
latter on the Schnelling, the Kohlgarten and other places. 
The entire absence among the rolled masses of the greywacke of 
certain kinds of granite, although they compose whole mountaims im 
the immediate vicinity of these formations, and also of fragments of 
the quartzose porphyry, is a proof that these rocks burst forth after 
the deposition of the transition beds, and consequently belong to the 
more recent plutonic formations. 
The very remarkable dislocations which the transition rocks of the 
southern Schwarzwald have experienced furnish further proofs that 
after their deposition elevations and eruptions of plutonic rocks have 
taken place on a very large scale in the Schwarzwald. Whilst a con- 
siderable portion of these deposits still occur in the bottom of the 
valleys, other portions have been torn from their original connection 
and are now found raised up and isolated on the top of the moun- 
tains, so that the deposits in the valleys and those on the heights are 
divided by whole mountains of plutonic rocks. Thus the transition 
strata are found in the bottom of the valley near Oberweiler and 
Schweighof, and then after being interrupted by granite and porphyry 
on the neighbourmg summits of the Sirnitz-Kopf and even of the 
Kohlgarten. In the Albthal near Bernau they form the valley, and 
then appear near the summit of the Blosslings and on the very top 
of the Spiesshorn. Other instances might be given. These immense 
