decide. It is impossible* however, to avoid being struck
by the coincidence between these physical and moral
changes in the human race, and the gradual alteration in
the forms of the vegetable world, which are observable
as we advance from a wet to a dry climate.
From Nako we proceeded, on the 26th of August, nearly
due north, to Chango, about ten miles up the Piti valley.
Nako is situated on the shoulder of the great mountain
Porgyul, which rises to a height of 10,000 feet above
that village, and Chango is at the very extremity of a
long spur given off by that mountain further east: it
is therefore separated from the Nako spur by a valley
of considerable size, which descends abruptly towards
the Piti river. Our road lay in a long sweep round the
deep bay formed by this valley, at an elevation not lower
than that of Nako, crossing in the most receding part
a foaming torrent which descends from the perpetual
snows of the mountain behind. Half a mile from Nako,
and scarcely lower than that place, is a patch of cultivation,
watered, as I was surprised to find, by a conduit
brought more than a mile along the side of the hill from
the stream which occupies the mid-valley; the water of
which was collected into several ponds, one above another,
in which it was kept in reserve till required for irrigation.
The crops cultivated were buckwheat and a species of
JBrassica, both in flower. A number of poplars and willows
were planted along the stream, but no fruit-trees.
Beyond this cultivated tract, the road, till we reached
Chango, was entirely barren. For several miles we continued
to pass through a most extraordinary accumulation
of transported blocks, scattered irregularly on the
gently sloping sides of the mountains. They covered a
very large area, and occurred in such almost incredible
profusion, that the road seemed to lie in a hollow among
fragments of rock on all sides. They were all angular;
and at so considerable an elevation as 12,000 feet, I
have now no hesitation in referring them to glacier action.
The rock in situ was clay-slate, with copious granite
veins, and the boulders were in general the same.
In one place, however, a dark mica-slate, with large
crystals of cyanite, was the predominating rock of the
erratic blocks, which no doubt might have been traced to
its source in the ravine above, as I nowhere saw it in situ
during the day.
After passing the torrent which occupies the centre
of the valley, the road very gradually approaches the
Piti river, from which it had at first receded considerably.
We could now observe that the mountains which
overhung the river in this part of its course were much
less precipitous, and the valley wider and more open,
than around Lio. Alluvial beds of great thickness everywhere
rested on the ancient rocks, assuming the most
diversified forms, but in general thicker and higher on
the sides of the hills, at some distance from the river,
than in the centre of the valley. About a mile and a
half from Chango, the road began to descend rather
rapidly along a dry water-course filled with huge boulders.
It then crossed a stream, which had cut for itself
a very deep channel through the alluvial conglomerate,
and ascefided slightly to the village of Chango. Close
to the last stream was a bed of very fine clay, which
had a thickness of at least twenty-five feet, and did