Personal Narrative Of Travels To The Equinoctial Regions Of America During The Years 1799-1804 - Volume 3 - By Alexander Von Humboldt And Aime Bonpland.
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(B) Limestone Of Paris Or
Coarse Limestone, Limestone With Circles, Limestone Of Bolca,
Limestone Of London, Sandy Limestone Of Bognor; Lignites.
(C)
Silicious limestone and gypsum with fossil bones alternating with
marl.
(D) Sandstone of Fontainebleau. (e) Lacustrine soil with porous
millstone grit. (e) Alluvial deposits.)
1. CO-ORDINATE FORMATIONS OF GRANITE, GNEISS AND MICA-SLATE.
There are countries (in France, the vicinity of Lyons; in Germany,
Freiberg, Naundorf) where the formations of granite and gneiss are
extremely distinct; there are others, on the contrary, where the
geologic limits between those formations are slightly marked, and
where granite, 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 (longitude 70
to 71 degrees), gneiss (longitude 68 1/2 to 70 degrees), and
mica-slate (longitude 65 3/4 to 66 1/2 degrees); but considering
altogether the geologic constitution of the coast and the Sierra
Parime, we prefer to treat of granite, gneiss and mica-slate, if not
as one formation, at least as three co-ordinate formations closely
linked together. The primitive clay-slate (urthonschiefer) is
subordinate to mica-slate, of which it is only a modification. It no
more forms an independent stratum in the New Continent, than in the
Pyrenees and the Alps.
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