386 
SEEPESTIKE AJTD GEEEKSTOEE. 
n-odification of the primitive mica-slate of Maniquarez, 
coiitnimng garnets cyanite, and rutile titanite. ^These 
insensible passages from primitive to transition strata, by 
clay-slate which becomes carburetted at the same time that 
t presents a concordant position with mica-slate and gneiss 
have also been observed several times in Europe bfcele- 
geologists. The existence of an iiidependei'it lor- 
mat on of primitive slate (urthoiischiefer), may even be 
c oubted that is, ot a formation which is not jofned below 
pLits.”*'*' vestiges of raonocotyledonous 
am of the liLtoial Cordillera, is separated from micaslate- 
gneiss bv a co-ordinate formation of serpentine and diorito 
It IS divided into two shelves, of which the upper presents 
green stcatitous slate mixed with amphibole, and the lower 
dark-blue shite, extremely fissile, and traversed by immel 
ous veins of quartz. I could discover no fragmentary stra- 
m (graiivvacke) nor kioselschiefer nor chiastolithe. The 
lueselscliicfcr belongs in those countries to a limestone 
(m2rwhh-h Bpecimens of the chiastolithe 
(nacle), which the Indians wore as amulets, and which 
came from the Sierra Nevada de Meriaa. This substance is 
probably found in transition-slate, for JIM. Eivero and 
Boussuiganlt observed rocks of clay-slate at the height of 
-“'““I-”*. » S<>i"8 from 
OF SeuPEETIITE AND DlOETTE rGnEFN- 
nf^.J' n ^''dicated above, a layer 
f gramtiferous serpentine inclosed in the gneiss of Buemo- 
®“Perposed on that rock; we here find a ' 
tendbli'^f""* fi alternating with diorite, and ex- ^ 
tending from the ravine of Tuciitunen.o as far as Juncalito 
Diorite forms the great mass of this stratum ; it is of a dark- 
fereen colour, gi'auular, with small grains, and destitute of 
to rocks which all geologists have hitherto called nrimit ve rocks to 
s"trrm''ortoicrssi!"‘‘ - -Cdei: 
