he sands long before reaching the coast.
Their waterless channels are interesting, however, as evidence of a
time when climatological conditions on this coast were different. The
principal rivers of this region are Sama (which forms the provisional
boundary line with Peru), Tacna, Camarones, Loa, Copiapo, Huasco,
Elqui, Limari and Choapa. The Loa is the largest, having its sources
on the slopes of the Cordillera south of the Minho volcano, between
21 deg. and 21 deg. 30' S. lat., and flowing south on an elevated plateau
to Chiuchiu, and thence west and north in a great curve to Quillaga,
whence its dry channel turns westward again and reaches the Pacific in
lat. 21 deg. 28' S., a few miles south of the small port of Huanillos. Its
total length is estimated at 250 m. The upper courses of the river are
at a considerable elevation above the sea and receive a large volume
of water from the Cordilleras. The water of its upper course and
tributaries is sweet, and is conducted across the desert in pipes to
some of the coast towns, but in its lower course, as in all the rivers
of this region, it becomes brackish. The Copiapo, which once
discharged into the sea, is now practically exhausted in irrigating a
small fertile valley in which stands the city of that name. The
Copiapo and Huasco have comparatively short courses, but they receive
a considerable volume of water from the higher sierras. The latter is
also used to irrigate a small, cultivated valley. The rivers of the
province of Coquimbo--the Elqui or Coquimbo, Limari and Choapa--exist
under less arid conditions, and like those of the province of
Aconcagua--the Ligua and Aconcagua--are used to irrigate a much larger
area of cultivated territory. The central agricultural provinces are
traversed by several important rivers, all of them rising on the
western slopes of the snow-clad Andes and breaking through the lower
coast range to the Pacific after being extensively used to irrigate
the great central valley of Chile. These are the Maipo (Maypo or
Maipu), Rapel, Mataquito, Maule, Itata, Bio-Bio, Imperial, Tolten,
Valdivia or Calle-Calle, Bueno and Maullin. With the exception of the
first three, these rivers have short navigable channels, but they are
open only to vessels of light draught because of sand-bars at their
mouths. The largest is the Bio-Bio, which has a total length of 220
m., 100 of which are nav