HORNBLENDE. SLATE NOT A DISTINCT FORMATION. 
249 
and to ascend only in small quantity, or to 
disappear entirely on its higher margins.''^ 
In these latter situations, it either assumes 
a coarse granular structure, and passes into 
gneiss, as on the southern acclivity of Choura 
Pany, and into mica-slate, as below Durgura ; 
or it changes into a very fine granular de- 
scription of clay-slate, as in the bed of the 
Lohoo river, on the northern foot of Choura 
Pany. 
It may be more consistent with the nature 
and connexions of this rock, to imitate 
Werner and Professor Jameson, in consider- 
ing hornblende-slate, not as a distinct for- 
mation, as described by Raumei't, but as 
occurring only in beds ; but there can be no 
doubt that those beds are of much greater 
extent than either of those eminent geologists 
contemplated ; and as the term hed affords 
too contracted an idea of a rock, which com- 
poses an extensive portion of a district, the 
inconvenience might perhaps be avoided by 
substituting the tei’ms partial formationX. 
The direction of the strata of hornblende- 
slate is ruled, rather by the direction of 
mountain groups, than by that of px’incipal 
mountain chains ; or, in other words, its 
direction is subject to variation arising from 
local irregularities of the surface of the basin, 
in which it is deposited. The dip is seldom 
less than 60", and often as much as 80". 
The acclivities of mountains composed of 
this rock are usually rugged and inaccessible ; 
and tabular masses of nearly perpendicular 
strata stand several feet erect above the sur- 
face. From this peculiai-ity, soil sufficient for 
the growth of the most luxuriant vegetation is 
retained on the steepest acclivities. 
Oak being in this latitude the inhabitant 
of loftier altitudes than are formed by this 
rock, the forests that prevail on it are 
chiefly composed of pines of the largest 
growth. 
* On the S, W. acclivity of the principal 
mountain chain; or, in other words, the as- 
cent from Belket to Choura Pany, hornblende- 
slate is found, at the altitude of 6,000 feet, to 
change into the character of gneiss; and in 
the course of this mountain acclivity, conical 
peaks rise one above another. The centre 
of each peak is composed of granular horn- 
blende-slate, closely resembling gneiss, from 
which it only differs by coutaiixing hornblende 
sufficient to give it a greenish hue ; while the 
strata surrounding these centres retain the 
character of hornblende-slate, until we ascend 
to the altitude already mentioned, which ap- 
pears to be that at which hornblende-slate 
disappears. 
+ Annal. Phil. vol. vi. p. 478. 
+ To Raumer, green-slate occurred resting 
on gneiss and granite in the Riesengeberge ; 
to Werner it occurred in clay-slate. In Ke- 
maon, it is found resting on gneiss. To these we 
might perhaps apply the terms of first, second, 
and third trap (or partial trap) formations ; 
but it is highly probable, that, in a more 
advanced state of Geological Science, these 
seeming irregularities may be reconciled to 
some general law, which has hitherto elu- 
ded our observations. This is the more pro- 
bable, as our geognpstic acquaintance with the 
structure of the earth is as yet confined to a 
comparatively small proportion of the whole 
surface. 
The tract of district composed of horn- 
blende-slate, although of considerable extent, 
is almost totally deserted ; and the few vil- 
lages that are found on it, are miserably 
poor, and, in general, uninhabitable for 
several months during the year; as well 
fi’om the miasmata and heat that prevail in 
its dense forests, and deep valleys, as from 
the rapacity of the wild beasts by which 
these are infested : as the tiger, leopard, and 
the bear. 
Hornblende-slate having been found in so 
many different positions, with respect to 
other rocks, a minute description of it, as it 
occurs in Kemaon, resting on gneiss, may be 
useful in assisting to form its separation 
into species, depending on the rocks with 
which it is associated in nature. , 
Its colours are seladon, pistachio, and 
olive-green. 
It occurs massive, and contains cotera- 
poraneous laminae of quartz, in thin alternate 
layers, and fiattish grains, from small to very' 
small ; and even finely disseminated. External 
lustre, dull, inclining to resinous. Fracture 
foliated, and slaty, with a single cleavage. 
Lustre of the principal fracture glistening, 
or shining, and of the cross fracture, glim- 
mering. Shape of the fragments, tabular. 
Distinct concretions, lamellar. It affords a 
greenish grey streak. It is opaque. It is 
semi-hard. It is somewhat sectile. It af- 
fords an earthy smell when breathed on, 
and feels rather meagre. Specific gravity, 
2*920. 
Chemical characters. It is not fusible 
before the blow-pipe ; probably from its 
intermixture with common clay, a large pro- 
portion of mica, and other impurities, as 
its lightness indicates. 
Variat. a . — Coarse Granular. 
Its colours are greenish grey, seladon, and 
pistachio green ; wdth a pearly and glimmer- 
ing lustre. Fracture, coarse granular ; but 
somewhat inclining to slaty. Lustre of the 
fracture, resinous and slightly shining. Dis- 
tinct concretions are lenticular, inclining on 
the one hand to lamellar, and on the other 
to granular. Specific gravity, 2*708. 
It appears to contain felspar, as well as 
quartz, and may be considered as the transi- 
tion between hornblende-slate and gneiss. 
Variat. b. 
Colour, dark greenish grey. Fracture, 
slaty in the large, but compact, even, and 
inclining to eaxdhy in the small. Lustre, 
glimmering. It is opaque. It is similar in 
the streak. It is semi-harcl, inclining to 
soft, and affords a strong bituminous smell 
when bi*eathed on. Specific gravity, 2*728. 
This I'ock is a transition between horn- 
blende-slate and clay-slate ; and appears to 
be composed of minute gx’ains of quartz, 
imbedded in a basis of clay and hox’xiblende. 
The fox*eign beds, which are contained in 
hornblende -slate, are gypsum, micaceous iron 
glance, eommon iron glance, chlorit- slate, and 
px’imitive green-stone. 
The first is common to this I'ock, and 
mica-slate, and v^ill be noticed in the next. 
