But irria eftlcaTeoris2 feeftohe %>£ • tine northern ridgbsrrif trherooaft, Hum-
' ftrimbers femjogky ^idds«itr^t*&aid^j :afc
they are thole of the-feaj now0ame leagues diftant. , |The belemnite and
krmndh?t'i'fef6rh unkriowfi^ though ft erimm&rriiri ‘EtewJpfci $ Ia tfe pldin.
rif'Onflo^5petrifiedtrdes are found,- in a caarfe breccia.’“
Con&uftion. v1 Among the primitive rocks Humboldt mentions granite, which forms
the chain of Parima; while in that of the coaft it is covered, or mingled
with gneifs. and nficaOedgTfchiftus. It is fometime.s "ftratified in beds,
from two to three'feet'thick ; arid fometimes contains large c iy fta l of
felfpar. The micaceous fchiftus fometimes prefents. red garriets, and
fappare ; and in the gneifs o f the mountain of Avila green garnets-appear.
Sometimes nodules o f granite are found in the fame fubOunce,
or in gneifs, confiding o f finer grains gathered by forrie local attraction.
In the range of Parima there, occur large mafleS o f moft brilliant talc,
formerly imparting fuch reputation to the Dorado, fituated between the
rivers Efquibo and Mao, and other mountains, which,, like burnilhed
.gold, refteS the. light of the fun. I f Sir Walter Ralegh had refle<ftecl
that all that glitters is not gold, he migh t have faved hisTatal voyage to
ELDorado. Sme&ite.or fofi iad is fornrndfnttf idmSy fa a Coriaa‘wn|
^ifeovered th^t-variety of^hird jad cajlerd A m & none,la gBy
applied -to the blue-felfpar. of Siberia.* Schi^ofe alfo occurs;
and beautiful hornblende; rifes through, the .nreetg of'GuaianC'or
S. Thome. Other- fubif%n£e& are, decompofe^&|p^r m kaolin, primitive
limeftone, plumbago ; and there are veins o f quart^whkl^ordaiji
auriferous pyrites, and antimony, native gpl^jgyfy0jpp||er, j.g®ma|a-
chite. * The copper mines of Aroa are afgne
x co^ quintals yCariy. Slate-is tarty but fitftnetknes
fchiftus; and in the northern chain there rirerroeks o f &r^Qtine^tefcgdL
•with bluifll fteatite. The grunftein of Werner fometimes occurs inj' that
ridge.
Among the rocks called tranfitive by Werner, as conmeding^the primitive
with the fecondary, are,trap, green flate, amygdaloid, and the
fchiftofe porphyry of that author., green.with cryftals of felfpar. The fe-
• cqqdary
dârp rocks ate limeflieine1, -‘^fpfum, argiliaceous fehiftris,' and freeftone
ôFdâica'febüs fandftone, with ccm*%breecia;f -f
A’ ’prridlical German nA^^aloglffy; employed for fome -years--in the
m'Àiés of Peruff-ftmForiiris us that the éàîftem ïpurs/of the Andes fome?*
times prefeht red and;gréeri-grâüite^knd gaeife,'as towards Gordova- and
Tfidumàn ; but2 the Gÿâlî#;Chà1a=%MëIpèbffliftâ bf àigilMèe©üs;^iftus,
dr Brians kinds of thick flate, bliiifli, dark red^fleflf 'coiohr,- grey, and
yéfîHW ‘ o’fl which, in many plhees,’' are incurtabent fttta1 of lim'eftend,
dm lâfge ' maffesr' o f : Ferrugiriou's’ farid’^ftoriCi ’ Neither-, in Hungary:,
oaxbnÿ rrOr thè Pÿreriées; had oüf aiit-lior beheld riaotintaibs fo-irregular
às me Andes, ©rDroken into fuch'Altbrriafê fuMFanrièê,*’ revealing fome
prodigious^revofMon of natrireV s- Amicf ■ thé' Argillaceous TcMftris- thè
metals fometiriieS oc'curfri' veins of' quarts,*’fdmet'imfes in alluWIHkyers
of larid-ftône and iron land; Near Pofefi aVéi'iriegulàîr beds’ -,ëf -large
bullets of ‘ grk’nitriV and the celebrated mbuntairi, fd bib® in -filler- orb,
is'chiefly compofed of a firm* yèîl'otsr ‘âÿgHIaeebus ïfâte, full of vèins of
ferfugindu's quartz, in WfhielfTdme of t§è: hell ories are found. In palling
theTugheflTfiflge“of the Andes, between Ptrtoli ‘arid Lima, Hel'm-s ftill
found argillaceous fchiftus the- predominant fifqifance ; fometimes with
ftrata of fand-ftorie, fometirhës with ’lorig Extents of granité.1 Near tHè
late of Titicaca the Andes, are“ bf proqigidris''height, ‘(mis blftùg the
ceiïtre of the chain, and perhaps equallin^feb5 mmmits rieaV,(!^offo!)i';
and" Helms' obferved In fome places the- balls of argillaceous fdhiffus
covered with alluvial layers of rttarlj gypfum, liméftynt^ fand, fragments
of porphyry, arid evbri fdek lalt ; yet rifch filvbf 'occuiS' iri'iburidaricb^
• A t the end of Humboldt’s paper is a iketch of a primitive and fecondary-rock, of the chain of
the coaft, and that of Parima. Both reft on màffive granite often mingled with jad and plumbago.
This is followed, in the'Primary, by foliated granite', micaceous fchiftus with garnets, primitive flate
with beds of native alum, flate mixed with hornblende, grunftein (which he calls primitive trap) ,.
amygdaloid, while the fummit is fchiftofe porphyry. In the Secondary, the mafs of granite is
furmounted by gneifs, with beds of primitive limeftone ; the micaceous fchiftus with fchiftofe
plutabago, and limeftone ; the fame with beds o f Lydian ftone and petrofilex, gypfum, calcareou*
freeftone. His plumbago feems to be hornblende,
f Tagebuch ejner Reife, &c, j A Journal of a Journey'thro^A Peru, from. Buenos-A^res on.
the great river La Plata, by Potofi to Lima, the Capital of the fohjj4®n''of ' Peru. By Antho'ny
ZachariaB Helms, Royal Spànlfe Diredtor of Mmes. 8vol pp. 300, Drefden, -1758. <•
M ountains.
Conftruftion
of the -
Andes.
Near