 Bolivia
Geography
Landlocked
Bolivia sits astride the Andes in the west-central part of
the South American continent. With an area of 1,098,581
square kilometers, the country is about the size of Texas
and California combined, or twice the size of Spain. Bolivia
has 6,083 kilometers of land boundaries, which adjoin five
countries. The country is bounded by Brazil to the north and
east, Paraguay to the southeast, Argentina to the south,
Chile to the southwest, and Peru to the northwest
Natural
Regions
Stretching
in a broad arc across western Bolivia, the Andes define the
country's three geographic zones: the mountains and
Altiplano in the west, the semitropical Yungas and temperate
valleys of the eastern mountain slopes, and the tropical
lowlands or plains (llanos) of the eastern lowlands, or
Oriente. The Andes run in two great parallel ranges or
cordilleras. The western range (Cordillera Occidental) runs
along the Peruvian and Chilean borders. The eastern range
(Cordillera Oriental) is a broad and towering system of
mountains stretching from Peru to Argentina. Between the two
ranges lies the Altiplano, a lofty plateau 805 kilometers
long and 129 kilometers wide
Mountains
and Altiplano
The
Cordillera Occidental is a chain of dormant volcanoes and
solfataras, volcanic vents emitting sulfurous gases.
Bolivia's highest peak, the snowcapped Sajama (6,542
meters), is located here. The entire cordillera is of
volcanic origin and an extension of the volcanic region
found in southern Peru. Most of the northern part of this
range has an elevation of about 4,000 meters; the southern
part is somewhat lower. Rainfall, although scanty
everywhere, is greater in the northern half, where the land
is covered with scrub vegetation. The southern area receives
almost no precipitation, and the landscape consists mostly
of barren rocks. The entire Cordillera Occidental region is
sparsely populated, and the south is virtually uninhabited.
The
Altiplano, the high plateau between the two cordilleras,
comprises four major basins formed by mountainous spurs that
jut eastward from the Cordillera Occidental about halfway to
the Cordillera Oriental. Along the Altiplano's eastern side
is a continuous flat area, which has served as Bolivia's
principal north-south transportation corridor since colonial
times. The entire Altiplano was originally a deep rift
between the cordilleras that gradually filled with highly
porous sedimentary debris washed down from the peaks. This
sedimentary origin explains its gradual slope from north to
south; greater rainfall in the north has washed a larger
quantity of debris onto the platform floor.
The most
prominent feature of the Altiplano is the large lake at its
northern end, Lake Titicaca. At 3,810 meters above sea
level, it is the highest navigable body of water in the
world. With a surface area of 9,064 square kilometers, it is
larger than Puerto Rico and is South America's largest lake.
Lake Titicaca is also deep, about 370 meters at its maximum,
but with an average depth of 215 meters; its volume of water
is large enough to maintain a constant temperature of 10°
C. The lake actually moderates the climate for a
considerable distance around it, making crops of corn and
wheat possible in sheltered areas.
Lake
Titicaca drains southward through the slow-moving, reed
filled Desaguadero River to Lake Poopó. In contrast to the
freshwater Lake Titicaca, Lake Poopó is salty and shallow,
with depths seldom more than four meters. Because it is
totally dependent on seasonal rainfall and the overflow from
Lake Titicaca, Lake Poopó's size varies considerably.
Several times in the twentieth century, it nearly dried up
when rainfall was low or the Desaguadero River silted. In
years of heavy rainfall, however, Lake Poopó has overflowed
to the west, filling the Coipasa Saltpan with shallow water.
Rainfall
in the Altiplano decreases toward the south, and the scrub
vegetation grows more sparse, eventually giving way to
barren rocks and dry red clay. The land contains several
salt flats, the dried remnants of ancient lakes. The largest
of these is the Uyuni Saltpan, which covers over 9,000
square kilometers. The salt is more than five meters deep in
the center of this flat. In the dry season, the lakebed can
be traversed by heavy trucks. Near the Argentine border, the
floor of the Altiplano rises again, creating hills and
volcanoes that span the gap between the eastern and western
cordilleras of the Andes.
The much
older Cordillera Oriental enters Bolivia on the north side
of Lake Titicaca, extends southeastward to approximately 17
south latitude, then broadens and stretches south to the
Argentine border. The northernmost part of the Cordillera
Oriental, the Cordillera Real, is an impressive snow-capped
series of granite mountains. Many of these peaks exceed
6,000 meters, and two--Illimani (6,322 meters), which
overlooks the city of La Paz, and Illampu (6,424
meters)--have large glaciers on their upper slopes. South of
17 south latitude, the range changes character. Called the
Cordillera Central here, the land is actually a large block
of the earth's crust that has been lifted and tilted
eastward. The western edge of this block rises in a series
of steep cliffs from the Altiplano. The backbone of the
cordillera is a high, rolling plain, with elevations from
4,200 to 4,400 meters, interspersed with irregularly spaced
high peaks. Too high to be exploited for large-scale
commercial grazing, this area takes its name from the
predominant vegetation type, the puna.
Yungas
and Other Valleys
The
northeastern flank of the Cordillera Real is known as the
Yungas, from the Aymara word meaning "warm
valleys." The steep, almost inaccessible slopes and
peaks of this mainly semitropical valley area northeast of
La Paz offer some of the most spectacular scenery in
Bolivia. Rainfall is heavy, and lush vegetation clings to
the sides of narrow river valleys. The land is among the
most fertile in Bolivia, but poor transportation has
hindered its agricultural development. The government
attempted to build a railroad through the Yungas in 1917 to
connect La Paz with the eastern lowlands. The railroad was
abandoned, however, after completion of only 150 kilometers.
The
eastern slopes of the Cordillera Central descend gradually
in a series of complex north-south ranges and hills. Rivers,
draining to the east, have cut long narrow valleys; these
valleys and the basins between the ranges are favorable
areas for crops and settlement. Rich alluvial soils fill the
low areas, but erosion has followed the removal of
vegetation in some places. The valley floors range from
2,000 to 3,000 meters above sea level, and this lower
elevation means milder temperatures than those of the
Altiplano. Two of Bolivia's most important cities, Sucre and
Cochabamba, are located in basins in this region.
Lowlands
The
eastern lowlands include all of Bolivia north and east of
the Andes. Although comprising over two-thirds of the
national territory, the region is sparsely populated and,
until recently, has played a minor role in the economy.
Differences
in topography and climate separate the lowlands into three
areas. The flat northern area, made up of Beni and Pando
departments and the northern part of Cochabamba Department,
consists of tropical rain forest. Because much of the
topsoil is underlain by clay hardpan, drainage is poor, and
heavy rainfall periodically converts vast parts of the
region to swamp. The central area, comprising the northern
half of Santa Cruz Department, has gently rolling hills and
a drier climate than the north. Forests alternate with
savanna, and much of the land has been cleared for
cultivation. Santa Cruz, the largest city in the lowlands,
is located here, as are most of Bolivia's petroleum and
natural gas reserves. The southeastern part of the lowlands
is a continuation of the Chaco of Paraguay. Virtually
rainless for nine months of the year, this area becomes a
swamp for the three months of heavy rains. The extreme
variation in rainfall supports only thorny scrub vegetation
and cattle grazing, although recent discoveries of natural
gas and petroleum near the foothills of the Andes have
attracted some settlers to the region.
Most of
Bolivia's important rivers are found in the water-rich
northern parts of the lowlands, particularly in the Alto
Beni (Upper Beni), where the land is suitable for crops such
as coffee and cacao. The northern lowlands are drained by
wide, slow-moving rivers, the three largest of which--the
Mamoré, Beni, and Madre de Dios--all flow northward into
the Madeira River in Brazil and eventually into the Amazon.
Riverboats along the Beni and the Mamoré carry both
passenger and freight traffic; rapids on the Madeira prevent
river traffic farther into Brazil. Near the Paraguayan
border, shallow sandy streams carry the seasonal runoff into
the Pilcomayo or Paraguay rivers.
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