GEATTITE AE'D GNEIS3. 
379 
I. CO-OEDINATB rOEMATIONS OE GtEAHITE, GnEISS, AND 
Mica-Si/Ate. — There are countries (in Trance, the vicinity 
of Lyons; in Germany, Freiberg, Naundorf) where the 
formations of granite and gneiss are extremely distinct; 
there are others, on the contraiy, where the geologic limits 
between those formations arc slightly marked, and where gra- 
nite, gneiss, and mica-slate appear to alternate by layers, 
or pass often from one to the other. These alternations 
and transitions appeared to me less common in the littoral 
Cordillera of Venezuela than in the Sierra Parime. We 
recognise successively, in the former of these two systems 
of mountains, above all in the chain nearest the coast, as 
predominating rocks from west to east, granite (long. 
70°— 71“), gneiss (long. and mica-slate (long. 
(35AO — considering altogether the geologic consti- 
porpliyries issue (like the trachytes of the Andes), in domes from the 
bosom of intcimediary rocks. Porphyrific breccias, which envelope the 
q\iartzose porphyries, (i) Zechstein or Alpine limestone, with marly, 
bituminous slate, fetid limestone, and variegated gypsum (Productus 
aculeatus). (c) Variegated sandstone (hunter sandstein) with frequent beds 
of limestone ; false oolites ; the upper beds are of variegated marl, often 
rauriatiferous (red marl, salzthon), with hydrated gypsum and fetid lime- 
stone. The gem-salt oscillates from zechstein to muschelkalk. (d) Lime- 
stone of Gdttingen or muschelkalk, alternating towards the top with 
white sandstone or brittle sandstein. (Ammonitis nodosus, encrinites, 
Mytilus socialis) : clayey marl is found at the two extremities of muschel- 
kalk. (e) White sandstone, brittle sandstein, alternating with lias, or lime- 
stone with graphites ; a quantity of dieotyledonous mixed with mono- 
cotyledonous plants. (/) Jura limestone of complex formation; a quantity 
of sandy intercalated marl. We most frequently observe, counting from 
below upwards ; lias (marly limestone with gryphites), oolites, limestone 
with polypi, slaty limestone with fish, Crustacea, and globules of oxide of 
iron (Amonites planulatus, Gryphtea arcuata). (ff) Secondary sandstone 
with lignites j iron sand ; Wealden clay ; greensand, or green sand- 
stone ; (A) Chlorite; tufted and white chalk; (planerkalk, limestone of 
Verona.) 
IV. Tertiary strata, showing a much smaller number of dicotyledonous 
plants, (a) Clay and tertiary sandstone with lignites ; plastic clay ; mol- 
lasse, and nagclfluhe, sometimes alternating, where chalk is wanUng, 
with the last beds of Jura limestone ; amber. (^) Limestone of Ians or 
coarse Umestone, limestone with circles, limestone of Bolca, limestone of 
London, sandy limestone of Bognor ; lignites, (c) Silimous limestone, and 
gypsum with "fossil bones alternating with marl, (tf) Sandstone m *<>"- 
tainbleau. (c) Lacustrine soil with porous millstone grit, (e) Alluvial 
deposits. 
