port of Puno. The outlet of the lake is
through the Desaguadero river. It has several islands, the largest of
which bears the same name and contains highly interesting archaeological
monuments of a prehistoric civilization usually attributed to the Incas.
Lake Pampa Aullaguas or Poopo is about 180 m. south-east of Titicaca,
and is fed principally by its outflow. It lies 505 ft. below the level
of Titicaca, which gives an average fall for the Desaguadero of very
nearly 21 ft. per mile. The Pampa Aullaguas has an estimated area of 386
sq. m., and has one large inhabited island. The lake is shallow and the
district about it is sparsely populated. Its outlet is through the
Lacahahuira river into the Coipasa swamp, and it is estimated that the
outflow is much less than the inflow, showing a considerable loss by
evaporation and earth absorption.

Having no sea-coast, Bolivia has no seaport except what may be granted
in usufruct by Chile.

_Geology._--The eastern ranges of ihe Bolivian Andes are formed of
Palaeozoic rocks with granitic and other intrusions; the Western
Cordillera consists chiefly of Jurassic and Cretaceous beds, together
with the lavas and ashes of the great volcanoes; while the intervening
plateau is covered by freshwater and terrestrial deposits through
which rise ridges of Palaeozoic rock and of a series of red sandstones
and gypsiferous marls of somewhat uncertain age (probably, in part at
least, Cretaceous). The Palaeozoic beds have yielded fossils of
Cambrian, Ordovician, Devonian and Carboniferous age. In southern
Bolivia Cambrian and Ordovician beds form the greater part of the
eastern Andes, but farther north the Devonian and Carboniferous are
extensively developed, especially in the north-eastern ranges. The
hills, known as the Chiquitos, which rise from the plains of eastern
Bolivia, are composed of ancient sedimentary rocks of unknown age. The
Palaeozoic beds are directly overlaid by a series of red sandstones
and gypsiferous marls, similar to the _formacion petrolifera_ of
Argentina and Brazil. At the base there is frequently a conglomerate
or tuff of porphyritic rocks. Marine fossils found by Gustav Steinmann
in the middle of the series are said to indicate an age not earlier
than the Jurassic, and Steinmann refers them to the Lower Cretaceous.
It is, however, not improbable that the series may represent more than
one geological system. No later marin