Untitled - The Alfred Russel Wallace Website

ON THE PACIFIC COAST 331
of Mancora. The peaks are often truncated cones, so symmetrical
that until closely examined they might be supposed the work of
art.
... At a little way within its mouth the river is only from So
to 100 yards wide, and this average breadth is preserved, so far as
I can learn, for at least 50 miles up. It is of no great depth, for,
when at its lowest, a man may wade over it in most places with
at least his head out of water ; but as the current is pretty strong,
and there are some deep holes, it is considered unsafe to ford it
on horseback. . . . Very rarely, and with risk and difficulty, are
heavy goods conveyed on a raft for a few miles up the stream.
There are no bridges across it, but ferries are established at the
villages and principal farms. The fluctuations of level throughout
the entire year rarely reach 10 feet, but in the anos de agua or
rainy years there have sometimes been floods to a much greater
height.
In ascending the valley of the Chira we come on a series of
alternating contractions and lake-like expansions, the latter at one
period no doubt really lakes. A little above the village of
Amotape, 1 1 miles from the sea, following the course of the river,
but only 7 in a straight line, the valley contracts, so that from the
base of the hills on one side to the base of those on the other
there is barely half a mile. From this point to above the small
village of Tangarara, on the right bank, a distance of 15 English
miles along the course of the river, there has been a large lake of
a long oval form, the ancient margin retiring from the actual riverbank
at one point on the north side nearly 3^ miles, and having
an average distance of 2 miles. Deep furrows, like river-courses,
extend from the widest part (called Monte Abierto) to the
adjacent hills, and in the rainy years rivers again run along them
and enlarge their beds. On the south side the space betueen the
river and the base of the cliffs is also of considerable breadth, and
has on it the villages of La Huaca and Bibiate in its lower part,
and higher up the large farm of Macacara, 10 miles from
Amotape.
There are similar contractions of the valley, with intermediate
lake-like expansions, up to 52 miles from the coast.
On examining the cliffs that bound the valley of the Chira. we
imd them to consist chiefly of alternating hcri/ontal layers of \vr\
various composition, some of them apparently repeated at various
depths. The uppermost stratum is in many parts
a calcareous
sandstone, of minute fragments of shells, grains of quart/, etc.,
more or less compactly welded together, When of open texture
it is the material for the filtering-stones, which are largely manu-
factured at Payta, and are not only used throughout the province,
but are exported to Guayaquil and other ports along the coast. . . .