80 
GEOLOGICAL ABILANGEJIEJTT. 
green, containing long crystals of vitreous feldspar, appears 
exposed. It is the real porphyrschiefer of Werner; audit 
would bo uitficult to distinguish, in a collection of stones, 
the phonolite of Parapara from that of Bilin, in Bohemia. 
It does not, however, here form rocks in grotesque shapes, 
but little hills covered with tabular blocks, large plates 
extremely sonorous, translucid on the edges, and wounding 
the hands when broken. 
Such are the successions of rocks, which I described on 
the spot as I progressively found them, from the lake of 
Tacarigua to the entrance of the steppes. Pew places in 
Europe display a geological arrangement so well worthy of 
being studied. We saw there in succession six formations: 
viz., mica-slatc-gneiss, green transition-slate, black transi- 
tion-limestone, serpentine and grunstein, amygdaloid (with 
pyroxene), and phonolite. 
I must observe, in the first place, that the substance just 
described under the name of griiustein, in every respect 
resembles that which forms layers in the mica-slate of 
Cabo Blanco, and veins near Caracas. It differs only by 
containing neither quartz, garnets, nor pyrites. The 
close relations we observed near the Ccrro de Chacao, 
between the grunstein and the serpentine, cannot surprise 
these geologists who have studied the mountains of Fran- 
conia and Silesia. Near Zobtenberg* a serpentine rock al- 
ternates also with gabbro. In the district of Grlatz the 
fissures of the gabbro are filled with a steatite of a greenish 
white colour, and the rock which was long thought to 
belong to the grunsteinsf is a close mixture of feldspar and 
diallage. 
* Between Tampadel and Silsterwiz. 
+ In the mountains of Bareuth, in Franconia, so abundant in grunstein 
and serpentine, these formations are not connected together. The ser- 
pentine there belongs rather to the schistose hornblende (hornblend- 
schiefer), as in the island of Cuba. Near Guanaxuato, in Mexico, I saw 
it alternating with syenite. These phenomena of serpentine rocks form- 
ing layers in euritc (weisstein), in schistose hornblende, in gabbro, and 
in syeuitc, are so much the more remarkable, as the great mass of gar- 
netiferous serpentines, which are found in the mountains of gneiss and 
mica-slate, form little distinct mounts, masses not covered by other tor 
mations. It is not tho same in the mixtures of serpentine and granulates 
limestone. 
