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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These
Waters, In Contact With Carbonate Of Lime, Even Give Rise To The
Deposits Of Subsulphate Of Alumina (Destitute Of Potash), Found Near
Halle, And Formerly Believed Erroneously To Be Pure Alumina Belonging,
Like The Porcelain Earth (Kaolin) Of Morl, To Porphyry Of Red
Sandstone.
Analogous chemical actions may take place in primitive and
transition slates as well as in tertiary formations.
All slates, and
this fact is very important, contain nearly five per cent of potash,
sulphuret of iron, peroxide of iron, carbon, etc. The contact of so
many moistened heterogeneous substances must necessarily lead them to
a change of state and composition. The efflorescent salts that
abundantly cover the aluminous slates of Robalo, show how much these
chemical effects are favoured by the high temperature of the climate;
but, I repeat, in a rock where there are no crevices, no vacuities
parallel to the direction and inclination of the strata, native alum,
semitransparent and of conchoidal fracture, completely filling its
place (its beds), must be regarded as of the same age with the rock in
which it is contained. The term contemporary formation is here taken
in the sense attached to it by geologists, in speaking of beds of
quartz in clay-slate, granular limestone in mica-slate or feldspar in
gneiss.
After having for a long time wandered over barren scenes amidst rocks
entirely devoid of vegetation, our eyes dwelt with pleasure on tufts
of malpighia and croton, which we found in descending toward the
coast. These arborescent crotons were of two new species,* very
remarkable for their form, and peculiar to the peninsula of Araya. (*
Croton argyrophyllus and C. marginatus.) We arrived too late at the
Laguna Chica to visit another rock situated farther east and
celebrated by the name of the Laguna Grande, or the Laguna del
Obispo.* (* Great Lake, or the Bishop's Lake.) We contented ourselves
with admiring it from the height of the mountains that command the
view; and, excepting the ports of Ferrol and Acapulco, there is
perhaps none presenting a more extraordinary configuration. It is an
inland gulf two miles and a half long from east to west, and one mile
broad. The rocks of mica-slate that form the entrance of the port
leave a free passage only two hundred and fifty toises broad. The
water is everywhere from fifteen to twenty-five fathoms deep. Probably
the government of Cumana will one day take advantage of the possession
of this inland gulf and of that of Mochima,* eight leagues east of the
bad road of Nueva Barcelona. (* This is a long narrow gulf, three
miles from north to south, similar to the fiords of Norway.) The
family of M. Navarete were waiting for us with impatience on the
beach; and, though our boat carried a large sail, we did not arrive at
Maniquarez before night.
We prolonged our stay at Cumana only a fortnight. Having lost all hope
of the arrival of a packet from Corunna, we availed ourselves of an
American vessel, laden at Nueva Barcelona with salt provision for the
island of Cuba.
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