Geology of Pacific
South America and
the Andean Region
By: Becky Baker, Marissa Bond,
Collin Whelley, Jackie Nagel
November 17, 2004
Introduction
 Four Themes
 Formation of the
Andes
 Atacama Desert
Geology
 Galapagos Islands
 Amazon River Basin
CW
What is the “Andean Region”
 The Andes Mountain Range
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Second highest range in the
world
 The areas of geography on
either side
 The indigenous peoples

CW
“ of Andean decent”
Formation
 Nazca and South American Plate Boundaries
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Subduction Zone
The Rise: late Tertiary period
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(40 million years ago)
Volcanic Process

CW
South American plate is moving westward while
the Nazca plate is moving eastward.
Magma cools in magma chambers creating
extreme pressure and violent eruptions
Nazca Plate vs. South American Plate
CW
The Subduction Zone
CW
Mountain Effects
 Ecology
 People
 Industry and
agriculture
 Earth quakes and active
volcanoes
 Climate effects
continued
CW
The Atacama Desert
 Location and Description
 Northern region of Chile
 Known as the “most arid desert in the
world”
 High altitude and cold temperatures
 Series of dry salt flanks
 Absence of rain and precipitation
 Wealth of desert based on mining
 Saltpeter and other fundamental natural
resources
MB
The Desert’s Aridity is explained by:
 Global and local climate aspects
 Geography and oceanography
factors
 The high mountains in the
Andes
 The flowing of the Humboldt
current
The result of these factors is:
 Large barren landscapes
 Variations of earthly colors
MB
The Geology of the Atacama Desert:
 Volcanic and erosive forces
 Volcanoes dominate the terrain
 Altiplano (high plane)
 Salt flats, multicolored lakes and hot springs
 Wind eroded hills and rock formations
Valle de la Luna
(Moon Valley)
Fantastic lunar
landscapes
Most inhospitable place
on the planet
MB
Geological Landscapes:
 El Tatio Geysers
 Highest geysers in the
world
 Strange mineral
formations
 86 degree Fahrenheit
hot springs
 Fumaroles and
mountains
MB
Geological Landscapes (cont.)
 Salar de Atacama
(Salt Lake)
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MB
Chile’s largest salt flat
Extraordinarily dry air
World’s largest lithium deposits
Geological Formations:
 Cordillera de la Sal (Salt Hills)
 Horizontal rock and sediment layers
 Tertiary periods (ca. 23 millions years ago)

Wind and rain erosion sculpt formations
 Gypsum creates salt-sprinkled look
MB
Left: red salt water due to algae
Right: thick layer of salt encrusts soil
Chilean Volcanoes:
 Lascar:
(Right)
 Active stratovolcano
 Erupted in 1993 and
2000
 Most active volcano in
the central Andes
Licancabur:
(Left)
Stratovolcano
Summit lake is one of
highest in the world:
 low oxygen, low
MB
atmostpheric-pressure
and high UV radiation
The Galapagos Islands
 Overview

Off the West coast of Ecuador in South
America
BB

Hot spot volcanoes

Belong to Ecuador (1832)
The Galapagos Islands

“Islas de Galapagos”

Charles Darwin (1835)
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
BB
Five year expedition
National Park
The Galapagos Islands
 Geology
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Hot spot volcanoes like Hawaii
Shield Volcanoes
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BB
Composed of Basalt
Non-explosive eruptions
16 Islands formed in Cenozoic Era: Pliocene
Epoch (5.1 to 2 million years ago)
The Galapagos Islands
 Geology (continued)
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BB
One of most active oceanic volcano areas on
Earth
Igneous Islands
Very young and still forming
The Galapagos Islands
 Volcanoes
 6 shield volcanoes
come together to form
the largest island,
Isabela
 Steeper than Hawaiian
Islands with barren
hardened lava areas
 Cliffs form jagged
points along the coast
BB
The Galapagos Islands
 Volcanoes (continued)
BB

Calderas/Cones (several thousand)

Unusual landforms produce a lunar-like
landscape
The Galapagos Islands
 Islands (Major of 16)
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Isabela
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Fernandina
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BB
Dry climate
Largest Island
70 miles long, covering half the land area of all
the islands put together
West of Isabela
Home of rare tortoises
The Galapagos Islands
 Islands (continued)
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Santiago
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Santa Cruz
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Charles Darwin Research Station (1964)
San Cristobol
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BB
Northeast of Isabela
Farthest east
Seat of government
The Amazon River Basin
 Introduction:
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JN
Second longest in
length in the world
It is estimated that the
Amazon discharges
between 9 million and
32 million gallons of
water per second
Accounts for one- fifth
of the world's liquid
fresh water
The largest and
wettest tropical plain in
the world.
Geology of the Amazon River
 Giant river valley bordered to the north and south by
the Guiana and Brazilian shields

Comprised of hard Precambrian rock
 Pacific marine like animals
 Water levels within the Amazon basin changed with
the sea level

JN
huge lakes formed in the valley
Location of the Amazon River
 Starts in Brazil and
flows to Ecuador

over 200 tributaries in
Brazil alone
 Mouth of the river is in
Brazil
 Bordered by Guiana
and Brazilian shields
 Previously opened into
the Pacific ocean
JN
Features of the Amazon River
 Headstreams are found in the heights of the Andes
 Average depth of the river
 150 miles wide at Atlantic estuary
 Rate of the flow
 Bed of the river
 World’s largest tropical
rain forest
(40% of South America’s
landmass)
JN
Effects on the Amazonian Rainforest
 Watershed and a wet
tropical plain
 Flooding of thousands
of square miles of forest
 Determinants of fish
distribution, behavior
and diversity within the
floodplain

JN
Habitats for animals
Animal Life of the Amazon
 over 2,000 types of fish
are in the Amazon River

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JN
Piranhas, 200 lb.
Catfish
Arapaima- largest
freshwater fish
Freshwater stingrays
Anaconda
Cuban Crocodile
Supporting Life in
the Amazon River Basin
 The forest shelters the
largest biodiversity of the
planet
 It helps to regulate regional
hydrology and climate,
protects the soil, ameliorate
floods, and supports
indigenous communities
 Great diversity of
indigenous languages
and cultures
 With nearly 400 different
ethnic groups, 1-1.5
million indigenous people
JN
Questions Regarding the Geology of Pacific
South America and the Andean Region:

What are the two major plates that were and are involved in the formation of the Andes Mountain range?
-CW

What does the Andean region include?
-CW

What fundamental mineral was at one time the leading export of Chile?
-MB

What mineral creates the salt-sprinkled look of the salt flats in the Atacama Desert?
-MB

What type of volcanoes make up the Galapagos Islands? Describe them.
-BB

How were the islands formed?

Were they on tectonic plate lines? geographic location? hot spot?
-BB

How much of the worlds fresh water is found in the Amazon River Basin?
-JN

MB
The mouth/inlet of the river is located in what country, while its outlet is located in the Pacific country of Ecuador?
-JN
Bibliography
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MB
“A Brief History of the Galapagos Island,” www.pbs.org/safarchive/5_cool/galapagos/g21_history.html (10 Nov 2004).
“Amazon Rising: Season of the River,” www.sheddaquarium.org/exh_amazon.html (13 Nov 2004).
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2004).
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Encyclopedia search, tiscali.,http://www.tinscali.co.uk/misc/ (14 Nov 2004).
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_History/Oceanography/Humboldt_Current.htm (12 Nov 2004).
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(12 Nov 2004).
“Licancabur Volcano,” http://amesnews.arc.nasa.gov/releases/2002/02images/lanca/lanca.html (12 Nov 2004).
MBarron.net Production 1998 www.mbarron.net/Amazon/bigmap.htm (13 Nov 2004).
Roach, John, National Geographic News (October 22, 2003)
news.nationalgeographic.com/news/2003/10022 031022 andesrise.html.
(14 Nov 2004).
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(12 Nov 2004).
The Columbia Electronic Encyclopedia, 6th ed. Copyright 2004, Columbia University Press.
www.factmonster.com/ce6/world/A0803618.html (13 Nov 2004).
“Valle de la Luna,” http://www.gochile.cl/Attr_s/htm/valuna.asp (12 Nov 2004).
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Geology of Pacific South America and the Andean Region