Download 7th grade geography

Compiled by Dr. Lorraine W. Hall 2005
The Big Blue Marble
GEOGRAPHY
 ge·og·ra·phy (noun)
1. The study of the earth and its features
and of the distribution of life on the earth,
including human life and the effects of
human activity.
2. The physical characteristics, especially
the surface features, of an area.
GEOLOGY
ge·ol·o·gy (noun)
1. The scientific study of
the origin, history, and
structure of the earth.
2. The structure of a
specific region of the
earth's crust.
TOPOGRAPHY
Detailed description or graphic
(picture) representation of a place
or region on a map, a description of
surface features.
topos (Greek) = place
graph (Greek) = draw or
record
island
A piece of land completely surrounded by
water, islands are of four types:
 Coral islands, formed by coral reefs
 Barrier islands, formed by build-up of silt
and sand
 Volcanic islands, formed by oceanic
volcanoes
 Continental islands, those such as
Tasmania that were once connected to a
continent
archipelago
a group or chain of islands
clustered together in a
sea or
ocean
Archipelago off the Coast
of Guinea-Bissau, Africa
atoll
a ring (or partial ring) of coral that
forms an island in an ocean or sea.
The protected
area within the
ring is a lagoon.
Coral Island Sipadan off coast of Borneo
coral reef
Coral reefs are found in warm,
shallow, tropical seas, such
as the South Pacific. Living
coral -forming animals come
in many colorful shades and
magical forms, from fan
shapes to brain coral. When
the animals die, they leave
limestone skeletons that form
the foundations and ridges of
coral reefs.
Pacific atoll as seen from space
Post World War II Nuclear
Experimentation on Bikini Atoll
Operation Crossroads was an atmospheric
nuclear weapon test series conducted in the
summer of 1946 at Bikini Atoll in the Marshall
Islands. The series consisted of two
detonations, each with a yield of 21 kilotons,
named shots ABLE and BAKER.
The series was intended to
study the effects of nuclear
weapons on warships,
equipment, and material.
The Initial Blast…
At 0900 on 1 July,
1946, test ABLE
detonated about 518
feet above the target
fleet. The surface
temperature of the
resulting fireball was
about 100,000
degrees Fahrenheit,
scorching wood, paint
and metal alike.
Bikini Atoll
Operation Crossroads
The full formation of the BAKER cloud
reached a height of 10,000 feet. The blast
column reached to the floor of the lagoon-some 200 feet deep--and spewed bits and
pieces of coral on the decks of the target fleet.
The cloud at its peak, shows the water column
and the familiar cauliflower-shaped cloud of
water vapor. Millions of gallons of water hung
in the atmosphere, where they mixed with
fission particles and became highly
radioactive.
barrier islands
As barrier islands disintegrate, the vast system of
sheltered wetlands along coastal areas are
exposed to increasing wave attack, salinity
(saltiness), and storm surge. Removal of the
barrier islands will accelerate destruction of
wetlands which are nurseries for many species of
fish and shellfish. The loss of the barrier islands
and protected wetlands will have a profound
impact on the fishing industry and the fragile
coastal environment.
Barrier Islands of North
Carolina Outer Banks
Barrier Islands act as a
protection against storms and
erosion to the continental
coastline.
√ Quick Check √
 What is the difference between geography
and geology as a study?
 Name four major types of islands and
describe how they are formed.
 How might an area’s topography affect the
lifestyle of a person living In that area?
 Describe the events and motivation for the
events on Bikini Atoll following WWII.
ocean
A body of saline (salt) water
occupying all or part of the
Earth's ocean basins. There are
five recognized oceans: the
Pacific Ocean, the Atlantic, the
Indian Ocean, the Southern
Ocean, and the Arctic Ocean.
Did you know?
 Oceans cover approximately 75% of the
earth’s surface! No wonder early explorers
used to think that the oceans formed the
edges of the planet.
 All the oceans are interconnected and have
a salinity (salt content) of about 3.5%
 At one time people thought the ocean floor
was relatively flat. Not so. It has mountains
valleys, plains, even sand dunes and
canyons.
Which ocean is nearest your
state?
Arctic
Atlantic
Pacific
Indian
Pacific
Southern
√Quick Check√
 Which Ocean lies between the Atlantic and
Pacific and borders India?
 What and where is the Mariana Trench?
Describe how it was formed.
 What provides the passageway between the
Atlantic and Mediterranean Sea basins?
 What and where is Telegraph Plateau?
 What are four major threats to the health of
our oceans?
The Pacific
 Balboa discovered and named this ocean as it
seemed very tranquil (pacific, like a pacifier) to him
when he first saw it. Little did he know that the
world’s tallest wave would be recorded here by a
US Navy ship in 1933 at 112 feet tall!
 It is home to the deepest point of Earth, the
Mariana Trench off the southwest coast of Guam.
At this point, the Challenger Deep is estimated to
be 36,198 feet deep. That would cradle Mount
Everest with more than a mile to spare!
Mariana Trench
The Mariana Trench is located north of
New Guinea in the Mariana Islands.
The Mariana Trench is the deepest point
on the Earth's surface. The deepest part
is called the Challenger Deep.
The Trench is about 36,000 feet below sea
level, which is about 6.8 miles down.
Compare that to Mount Everest, which is
a little over 29,000 feet or 5.5 miles high.
The Atlantic Ocean
The Atlantic, the
second largest
ocean, has
relatively few
islands, unlike the
Pacific. Most of
these are located
in the Caribbean.
The Ocean Floor
The Atlantic Ocean is separated from the Arctic
Ocean by a submarine ridge extending from
Greenland to Scotland; part of the floor (about
3,000 feet don) is known as “telegraph plateau”
because of the network of cables laid there. A
shallow submarine ridge across the Strait of
Gibraltar separates the Mediterranean basin from
the Atlantic and limits the exchange of water
between the two bodies.
The Great Transatlantic Cable
By the middle of the 19th century, a network of
telegraph poles strung across America
enabled Samuel Morse's invention to create
communication between cities across the
continent. Communicating with Europe was
another matter. Messages to London were
sent the old-fashioned way, aboard sailing
ships that could take weeks to reach their
destination. Though the need for a
transatlantic cable was obvious, the physical
challenges to laying one were enormous.
Telegraph Plateau
The project would require the production of a 2,000
mile long cable that would have to be laid three
miles beneath the Atlantic. Cyrus Field, a young
New York paper manufacturer, took up the
challenge.
 After 12 years of cajoling investors, several failed
attempts to lay the cable, and millions of wasted
dollars, Field and his team of engineers finally
succeeded. On July 27, 1866, when the wire was
finally in place, Field sent back the first message
to Europe: "Thank God, the Cable is laid." Since
then, nothing has broken his communications link
with Europe -- not storms, earthquakes or world
wars.
Indian Ocean
The Indian Ocean is
the third-largest body
of water in the world,
covering about 20%
of the Earth's water
surface. The ocean's
importance as a
transit route between
Asia and Africa has
made it a scene of
conflict.
In 2000, the
International
Hydrographic Org.
delimited a fifth world
ocean - the Southern
Ocean - from the
southern portions of
the Atlantic Ocean,
Indian Ocean, and
Pacific Ocean. It is
the fourth largest
ocean and, like the
Arctic, a circumpolar
body of water.
Southern Ocean
Arctic Ocean
The Arctic Ocean
surrounds the North Pole
between North America
and Eurasia. Located
entirely within the Arctic
Circle, the “Frozen
Ocean” is covered by
pack ice (2-14’ thick) year
round in most of its
central and western
portions. From the fjords
of west Greenland,
dangerous icebergs (like
the one that sink the
Titanic) originate.
Some Deep Ideas
Although man has walked upon the
moon and photographed the craters of
other planets, he still knows very little
about the great oceans on our own
earth.
People who study the ocean are called
oceanographers, while the study of the
oceans is called_________________.
Our Oceans are at Great Risk
 Increased pressures from
unregulated and over fishing
 Habitat destruction
 Pollution
 Introduction of invasive alien
species
 Global warming
All of these threaten the diversity of life in estuaries,
coastal waters and oceans, and the impacts could
be devastating for life in the sea.
bay
a body of water that is partly
enclosed by land (and is usually
smaller than a gulf).
Montego Bay, Jamaica
This mid bay barrier in Narrabeen- Sydney
(Australia), has blocked a former bay to form a
lagoon.
bight
A bight is a wide bay formed by a curve in
the shoreline. Looking at a map of
Australia's southern coastline, one can see
the curve which creates this bight.
This is a photo of the Great Australian Bight.
It is 685 miles across, from Cape Pasley in
Western Australia to Cape Carnot in South
Australia. Note the strata (layers) of rock.
gulf
A gulf is a part of the
ocean (or sea) that is
partly surrounded by
land and is usually
larger than a bay.
(Satellite image of
Persian Gulf 1990)
Satellite Image of Middle East 2003
Persian Gulf and Gulf of Aden
aquifer
Coastal Aquifer in Iceland
coastal aquifer
river
A large stream of water flowing in a bed
or channel and emptying into an ocean,
a sea, a lake or another stream; a
stream larger than a rivulet or a brook.
How many of the major rivers of the
world can you name?
river basin
River basin - The tract of country drained by
a river and its tributaries.
The actual rivers as shown
on the map
The Nile River
The Nile and its tributaries,
or branches, flow though
nine countries. The White
Nile flows though Uganda,
Sudan, and Egypt. The
Blue Nile starts in
Ethiopia. Zaire, Kenya,
Tanzanian, Rwanda, and
Burundi all have
tributaries, which flow into
the Nile or into Lake
Victoria. It is over 4,000
miles in length.
The Nile
Red squares are dams.
In ancient Egypt. . .
The calendar was divided into
three seasons, based on the
flooding of the Nile. During the
season of the Inundation, layers
of fertile silt were deposited on
the land. The Egyptian people
were drafted to work on the
pyramids and building projects
Hapi – The Nile Deity
during that time.
Amazon River Basin
mouth
sources
AMAZON: The Perfect Name
 For years, there has been discussion about whether
the Nile or the Amazon is the longer river. Both
rivers are approximately 4,000 miles in length.
 Because the Amazon drains the entire northern half
of the South American continent, including all the
tropical rains that deluge the rainforests, it carries an
enormous amount of water, depositing 20% of all the
freshwater discharged into the world’s oceans!
 At its widest point the Amazon is almost 7 miles wide
during the dry season, swelling to almost 25 miles
wide during the rainy season. Where the Amazon
opens at its estuary the river is over 202 mi wide!
Asia’s longest
river, over 3900
miles long, originates in the Tibetan
Plateau and , with
its 700 tributaries,
makes its way to
the China Sea.
A major source of
irrigation and
hydroelectric
power, approximately 400 million
people, a third of
China 's total
population, make
their homes here.
China’s Yangtze River
Three Gorges Dam Project
Construction on the
Three Gorges Dam
began in 1993 and
will end in 2009. The
total project cost is
estimated at $25 billion.
A lake about 400 miles
long will form behind
the dam. Over 1 million
People will be relocated.
Note reservoir
flooding land
behind dam.
Mississippi-Missouri River
s
With its tributaries, the Mississippi is over 3700 miles long.
Over 18 million people and more than 50 cities rely on the
Mississippi River Basin for daily water supply . At its
headwaters, the Mississippi is less than 3 feet deep. The
river's deepest section in New Orleans is 200 feet deep.
√Quick Check√
 Describe the length and path of the Nile and
its tributaries.
 Describe the path of the Amazon from
source to mouth.
 What is the Three Gorges project, and
where and why is it being carried out?
 Define and describe four geographic terms
associated with rivers.
Δ Δ Δ Δ delta Δ Δ Δ Δ
A delta is a low, watery land formed at
the mouth of a river. It is formed from
the silt, sand and small rocks that flow
downstream and are deposited in the
delta. A delta is often shaped like a
triangle, hence its name, delta, a Greek
letter that is shaped like a triangle.
The Nile Delta, Egypt
Mississippi Delta at New Orleans, LA
The Mississippi River
Delta is the modern
area of land built up by
silt deposited by the
Mississippi River as it
slows down and enters
the Gulf of Mexico. The
deltaic process has,
over the past 5,000
years, caused the
coastline of south
Louisiana to advance
gulfward from 15 to 50
miles.
Economic Importance of the
Mississippi Delta
It is a biologically significant region, comprising 3
million acres of coastal wetlands and 40 percent
of the salt marsh in the contiguous (connected)
United States. It is also a commercially
significant region, supporting the economy of
New Orleans with much shipping traffic,
providing 16 to 18 percent of the US oil supply,
and providing 16 percent of the United States’
fisheries harvest, including shrimp, crab, and
crayfish.
Problems in the Delta Area
Δ
Man-made changes to other parts of the
Mississippi River have a pronounced effect
on the Delta region. Dams, artificial
channeling, and land conservation measures
have caused a decrease in sediment carried
into the delta region, decreasing the rate of
build up of the Delta.
Δ
At the same time, the rate of loss of the Delta
has recently increased past the rate of build
up, causing a net loss of wetlands in the
Delta area. The rise of the sea level has also
caused increased erosion, as fresh water
vegetation, which previously protected
against erosion, dies due to the influx
(flowing in) of salt water.
Estuaries – Wetlands - Marshes
Protected wetlands or estuaries
provide rich breeding grounds
for plants and animals.
An estuary is a partlyenclosed body of
water where sea
water mixes with
fresh water, often at
the mouth of a river. A
very important
characteristic is that
there is an influence
of the ocean tide
creating a dynamic
relationship between
the two waters.
estuary
Mangrove ecosystems cover large areas of shoreline
between the Tropics of Cancer and Capricorn.
Transitional Ecosystem
Mangrove trees form the backbone of an
entire ecosystem. Leaves dropping from the
trees are eaten by many aquatic species,
and their extensive root systems shelter
small fish and juvenile shrimp from
predators, and help stabilize the soil. The
swamps are an important rest stop for
migratory birds on their journey south.
Additionally, humans have always harvested
mangrove trees for food, medicines, tannins,
fuel wood, and construction materials.
Adaptation
Mangroves thrive in the transition area between
the sea and fresh water. They have weird roots
that shoot back up from the soil and work kind of
like snorkels. Special pores in the gnarled,
exposed roots let the trees “breathe,” even at high
tide. Their leaves have special pores to excrete
salt. One tree may have several root systems to
help stabilize it against waves, wind and
hurricanes, making human movement through the
tangled root maze nearly impossible
Mangrove Swamp
The roots catch and hold particles of sand and silt,
thus helping to protect the shore and build up dry land.
Flood plain
Flooding occurs when a river, canal, or other
body of water rises above its normal level
and overflows its banks and covers the
adjacent, low-lying area, known as the flood
plain. People build dikes or levees to protect
this area. Building in these locations often
requires special flood insurance or zoning
exceptions. In recent years, human development
has caused great strain to the environment by
overbuilding in these areas.
Netherlands Flood Defense
Dikes protect polders
North Sea surge barriers
Netherlands Flood Protection
The Netherlands’ Delta Project started in 1958
(after a disastrous 1953 flood) and created a
defensive flood barrier capable of withstanding
the kind of storm that only happens once in
10,000 years.
More than half of the Netherlands’ landmass lies
below sea level and the Netherlands — its
name means ‘Low Lands’ — is also one of the
most densely populated countries in the world.
Under the Delta Project, huge multiple dikes
were built and a complex system of floodgates
created to keep the sea at bay and protect the
polders, or reclaimed farmland.
√Quick Check√
 What are transitional ecosystems and what
purpose do they serve?
 What is a mangrove and why is it important?
 Describe some factors that threaten
estuaries.
 How does a delta develop. Name two cities
located on a delta.
 Why, during the aftermath of Hurricane
Ophelia, were we happy to have the aid of
the government of Holland (the
Netherlands)?
continent
continent
The land mass on Earth is divided into 7
continents:
Europe
Asia
Africa
North America
South America
Antarctica
Australia
Pangaea
About 250 millions of years
ago, it was believed that
there was one huge
continent called Pangaea,
which means “all lands.”
Continental Shelf
country
The United Nations currently
recognizes 192 countries or
states. The largest is Russia, at more than 17 million
square kilometers; and the smallest is Vatican City,
which is less than a half a square kilometer in area. A
country, a land, is a geographical area that
connotes an independent political entity, with its
own government, administration, laws, often a
constitution, police, military, tax rules, and
population. Countries are shown by political maps,
rather than physical maps.
canyon
a deep valley with very
steep sides - often carved
into the Earth by the
eroding power of a river.
Grand Canyon of the
Colorado River
Grand Canyon
The muddy
Colorado is
seen at the
base of the
canyon.
Bryce Canyon National Park
Utah
Plateau, Mesa, Tableland
A plateau is an extensive land formation. The
top is flat or sloping; the elevation, from a
few hundred to several thousand meters.
A plateau is larger than a mesa or butte.
Mesa Verde National Park, Colorado
North America’s Columbia Plateau
A major plateau in
North America is
the Columbia
Plateau.
The Tibetan Plateau
This NASA satellite image of the Himalayan Range
shows the Tibetan Plateau near the centre and the
Takla Makan Desert Plain as the upper, lighter area.
crater
A crater is a funnel or
bowl-shaped depression,
most often found at the
top of volcanic cones.
Large sunken craters
may be as much as 20
miles in diameter. These craters are formed by the
sinking of the ground surface as supporting lava is
spewed out from underneath.
Crater Lake, Oregon,
is 6 miles across at its
widest point and the
deepest lake in the US.
No known outlets or
streams flow from it. The
caldera was formed
6,800 years ago, when
volcanic eruption
caused it to collapse
in on itself. It is one of
the largest eruptions in
the last 10,000 years.
escarpment
a steep slope or long cliff caused by erosion
or faulting separating two level areas of
differing heights.
Niagara Falls and the Great Lakes
Both Niagara Falls and the Great Lakes are the
result of a huge glacier bulldozing its way
across eastern Canada about 10,000 years
ago, grinding up rocks and soil. It dammed up
some lakes and gouged others out as it
moved and receded.
Harder rock eroded more slowly than softer
rock, and the powerful new waterways thus
carved these escarpments and falls areas.
Water Erosion at Escarpment
Niagara
Bruce
Peninsula
escarpments
√Quick Check√
 What is the difference between a canyon
and a crater, and how is their formation
process generally different?
 What is the relationship between an
escarpment and the falls that often are
present in such areas?
 What is the difference between a mesa and
a plateau?
Plate Tectonics Theory assumes
that the earth’s surface consists
of about twenty rigid plates that
are continually moving past
each other. This squeezes and
stretches the plates’ edges. If
the force becomes too great, the
plates rupture or break, causing
an earthquake. Most of these
ruptures or FAULTS lie beneath
the surface, but some, like the
San Andeas Fault in California,
are visible.
A Moving Experience
The earth's surface is broken into seven large
and many small moving plates. These
plates, each about 50 miles thick, move
relative to one another an average of a few
inches a year. Three types of movement are
recognized at the boundaries between
plates: convergent, divergent and transformfault.
Convergent Boundaries
At convergent boundaries, plates move
toward each other and collide.
Where an oceanic plate collides with a
continental plate, the oceanic plate tips
down and slides beneath the continental
plate forming a deep ocean trench (long,
narrow, deep basin), such as the trench at
the boundary between the oceanic Nazca
Plate and the continental South American
Plate.
Mariana Trench
At least 22 trenches
have been identified
with the Challenger
Deep, the deepest part
of this trench, being the
lowest point on earth.
The Trench is where
two tectonic plates
meet, and one is
undergoing subduction
or being forced under
the other.
Bathyscaphe Trieste
In 1960, two American Navy divers descended to the
bottom of the Trench in the Trieste. At the bottom
Walsh and Piccard were surprised to discover
flounder about one foot long, as well as shrimp.
According to Piccard, “The bottom appeared light
and clear, a waste of firm diatomaceous ooze” –
eukaryotic algae.
At the bottom of the Mariana Trench, water exerts a
pressure of 15,751 psi or pounds per square inch!
Diving Technology Sampling at the Bottom of
the Trench
Unicellular Marine Diatoms
The Appalachians
Where continental plates
collide, they form major
mountain systems,
such as the Himalayas.
Our Appalachians also
are a range formed
by a series of
continental collisions
that took place over
a period of more
than 1 billion years.
Mid-Atlantic Ridge
At divergent boundaries,
plates move away from
each other, allowing
hot, molten lava to rise to
the ocean floor. Cooling,
it adds new material
to the edges of the
oceanic plates, creating
mountains and renches,
such as the Mid-Atlantic
Ridge.
Rising to the Occasion
Some of the islands formed by this submarine
volcanic activity are the Azores, off the coast
of Africa, and the island of Iceland, which is
located at the northern end of the divergent
plate. These are places where the volcanic
eruptions have actually raised the level of
the land above sea level.
A true color image of Iceland captured
by NASA's Aqua satellite in 2004
Iceland
 Iceland has about 130 active volcanoes due to its
unique geological conditions. Over the past 500
years, Iceland's volcanoes have erupted a third of
the total global lava output. Geologists explain
this intense activity as being due to a combination
of the island's position on the Mid-Atlantic Ridge
and a volcanic hotspot underneath the island.
Iceland sits astride the boundary between the
European and American plates, and most volcanic
activity takes place along the plate boundary.
Iceland – Resting between the
Eurasian and North American Plates

Geo-thermal Activity
In geology, geothermal refers to heat sources
within the planet. Geothermal heat at the
surface is highly concentrated where
magma (hot lava) is close to the surface.
This primarily occurs in volcanic and hotspot
areas and at spreading ridge areas of
divergent tectonic plates. The island of
Iceland is one of these areas.
Island Hot Spot and Cold Spot!
 Being on a hot spot means that the island is
extremely geologically active. It has many active
volcanoes. Around 10% of the island is glaciated.
Iceland has many geysers, an Icelandic word
meaning “to gush.” Having much geothermal
power available means residents have hot water
and home heat for a low price. Electricity is
generally very cheap because of the many rivers
and waterfalls which are also used for the
generation of electrical power.
 The island itself has many fjords along the
coastline, which is also where most towns are
situated, because the island's interior, the
Highlands of Iceland, is a cold uninhabitable
desert.
fjord / fiord
A fjord is a long, narrow sea inlet in Norway
that is bordered by steep cliffs.
NOW . . .
Back to other
FAULTS
that will
really crack you up!
Transform Fault Boundaries
At transform-fault boundaries, plates move
horizontally past each other. The San
Andreas Fault zone is an example of this
type of boundary where the Pacific Plate on
which Los Angeles sits is moving slowly
northwestward relative to the North
American Plate on which San Francisco sits.
San
Andreas
Fault
Line
The San Andreas fault is dotted, and interpreted
rupture scenarios are shown; urban areas are gray.
The rupture line runs approximately 200km.
Almost all the earth’s major earthquakes occur in
two great belts: one cuts across Europe and Asia
from Burma to southern Europe. The other famous
seismic band is the Ring of Fire, which encircles the
Pacific Ocean and accounts for 75% of the world’s
earthquakes.
1923 Tokyo
Earthquake
The Great Rift is one of the most
interesting examples of Tectonic Plate
Theory.
Note
the Ysplit in
the
Great
Rift
area.
Will the
Horn of
Africa
be the
next to
break
off?
African – Arabian Plate
R. Maurer’s Theory
Engineer R. Maurer had some additional
ideas about Plate Tectonics, recently
published in 2001. He suggested that the
earth was behaving like an unbalanced,
rotating cylinder – like your laundry dryer
with an uneven load – trying to balance
itself. He theorized that the vibrations of the
rotating earth were causing the earth to
continually try to balance itself.
Crusty Tension on the Globe
Lighter and heavier unbalanced rotating bodies (like
the earth and the dryer) are continually in a state
of tension, trying to achieve balance.
In this case the geologically quiet and heavier
African Plate, which is splitting (Tension Zone) at
the Rift Valley, is “competing against” the
geologically active Pacific Basin’s Ring of Fire with
its deep trenches and subduction zones
(Compression Zone), as the earth tries to balance
itself.
Lake
Tanganyika
basin, formed
some 25 million
years ago when
a block of the
earth’s crust
dropped down
between blocks
that rise on
either side in
the Great Rift
area. At nearly
350 miles, it is
the longest lake
in the world and
reaches depths
of over 1400
meters. (NASA)
√Quick Check√
 Define and describe examples of three different
types of fault movements.
 What is Plate Tectonics?
 Give some examples of geothermal activity.
 What is Maurer’s relatively new theory regarding
changes in the earth’s surface?
 What is the Great Rift?
 What is the Mariana Trench? Give some specifics
about its formation, location, and size.
isthmus
A narrow strip of land
connecting two larger
landmasses, an isthmus
makes a natural place
to build a canal, as it
has water on both sides.
Isthmus of Panama
The isthmus was formed about 3 million years
when tectonic plate movement and silt and
sediment build-up joined islands into the isthmus.
peninsula
a strip of land
largely surrounded by
water and connected to
a larger land mass by a
narrow neck or
isthmus; any area of
land jutting out into a
lake or sea. Most of the
state of Florida is a
peninsula, as is most of
Italy and Baja California,
shown here. In Spanish,
baja means “below.”
volcanic peninsula
The word peninsula
comes from the
Latin words for
“almost island.”
Banks PeninsulaSouth Island of
New Zealand
lake
A lake is a large body of water surrounded by land
on all sides. Some large bodies of water commonly
called seas – the Sea of Galilee, the Aral Sea, the
Caspian Sea – are really lakes. Most lakes are
formed by glaciers that cut deep valleys and dam
up areas with glacial deposits. As the glaciers
melt, their water collects in these valleys. Most
are fed by rivers and mountain streams. Artificial
Lakes are made by blocking rivers and creating
reservoirs to regulate water levels behind a dam.
The Plight of the Aral Sea
Kazahkstan
2003
1985
Environmental Tragedy
The two major rivers feeding the Aral Sea were
diverted by the formerly controlling USSR to irrigate
the desert to raise the cash crop, cotton. Poorly
built irrigation ditches wasted about 70% of the
water. As the sea dried up, the receding waters left
huge plains covered by salt deposits and toxic
chemicals, so that the area is highly polluted. The
people are suffering from a lack of fresh water, as
well as from a number of other health problems.
Winds have picked up and spread the toxic dust to
the surrounding areas so that the population
around the Aral Sea now shows high rates of
certain forms of cancer and lung disease.
√Quick Check√
 What is the difference between a strait (not
a straight!) and an isthmus?
 Give some examples of major lakes that “go
by another name.”
 Discuss the tragedy of the Aral Sea and why
this has occurred. Do you think man has
been responsible in managing this
resource?
Mountains
From the Depths to the Heights
Earth’s tallest mountains on dry land are the
Himalayan Mountain Range, towering over
five miles above sea level. The highest peak,
Mount Everest, is over 29,000 feet above sea
level, astride the border of India and Nepal.
Strong winds of 118+ miles per hour, frigid
temperatures as low as -100°F, and lack of
Oxygen will not sustain plant or animal life.
Climbers accustom themselves to the lack of
Oxygen by a process known as acclimatization.
About 1500 climbers have reached the
summit of Everest, and about 200
have died making the attempt; many
bodies are still visible from the
paths! Ascending over 25,000 feet
above sea level puts climbers in
the “death zone,” where body
processes tend to shut
down due to lack of oxygen. It
literally leaves you breathless!
Mountains: What a Relief !
 Mountains cover about a fifth of the earth’s
surface. . .
 They are on all continents and even under the
sea. . .
 Mountains are formed by slow, but grand
movements of the earth’s crust. . .
Think of how you could fold, rumple, buckle, or
stack pieces of stiff pie dough to form peaks
and domes. Volcanic eruptions also build
mountains along fault lines or ruptures in the
earth’s crust. A string of mountains is a mountain
range.
What do the following all have
in common?
Mount McKinley
Mount Kilimanjaro (pictured here)
Mount Everest
Mount Kosciuszko
Mount Aconcagua
Mount Elbrus
RIGHT!!! Each is the HIGHEST mountain
on its respective continent!
Mt. Everest
(Asia – Nepal-India)
Mt. Aconcagua
Mt. McKinley
Mt. Kilimanjaro
Mt. Elbrus
Vinson Massif
Mt. Kosciuszko
(S. America – Chile/Argentina)
29,029 feet
22,835 feet
(North America – Alaska)
20,320 feet
(Africa – Tanzania)
19,340 feet
(Europe – Russia)
18,513 feet
(Antarctica)
16,066 feet
(Australia)
7,310 feet
Want to see a mountain shrink
overnight?
The volcano Mount Saint
Helens, in southwestern
Washington state began
to eruption March 27, 1980,
after a long period of
dormancy. The large-scale
eruption occurred May 18,
1980. This violent blast
sent clouds of ash and
other
volcanic debris into the
atmosphere and, the
mountain’s elevation
dropped from 9,677 to
8,365 feet.
A last word on Mountains…
Mountains are dynamic forms that change
over time
– As volcanic activity occurs
– As tectonic plates shift and move
– As glaciers advance and recede
– As weathering occurs
Weathering occurs through exposure to the
elements – snow, wind, rain.
– Even human activity effects change.
√Quick Check√
 What is the approximate distance between
the highest and lowest place on earth?
Where are they located?
 What factors can cause dramatic change in
terrain and topography over long periods of
time?
 What is dormancy in a volcano?
Biome
What is a biome?
 A biome is a large geographical area of distinctive
plant and animal groups, which are adapted to that
particular environment.
 The climate and geography of a region determines
what type of biome can exist in that region.
 Major biomes include deserts, forests, grasslands,
tundra, and several types of aquatic environments.
 Each biome consists of many ecosystems whose
communities have adapted to the differences in
climate and the environment inside that biome.
 Tundra is the coldest of the
biomes. Tundra comes from
the Finnish word tunturia,
meaning “treeless plain.”
 Two types:
*Arctic (with permafrost)
*Alpine
 Characteristics:
*extremely low temperatures
* little precipitation
*poor nutrients
*short growing seasons
*shrubby vegetation
Tundra
Taku Glacier, Alaska, 1929
glacier
Glaciers form when more snow falls in winter
than melts or evaporates in summer. The
excess snow builds up and freezes in
layers, becoming so thick that the glacier
begins to move under the pressure of its
own weight. Most glaciers range in
thickness from 300 to 10,000 feet! The
melting and refreezing of ice crystals help it
move downhill. Moraine is the pile-up of dirt
caused by a glacier’s movement.
Malaspina Piedmont Glacier
Alaska
This
glacier is
the
largest of
its type,
covering
5,000
square
kilometers
of coastal
plain.
(View from
Space)
Taiga or Boreal Forest
•Stretching over Eurasia and
North America, just below
the tundra, is the taiga.
Taiga is the Russian word
for “swamp forest, and
Boreal was the Greek
goddess of the North Wind.”
•Temperatures range from
-60° F in winter to a rainy,
humid 70° in summer, so in
summer there are millions of
insects.
•Coniferous trees are those
such as pines and hemlocks
which have long, waxy
needles to protect them
from drying out. Moose,
bobcats, hares, and weasels
thrive in the taiga.
Temperate Coniferous Forest
These are the evergreen
forest areas where you find
the bear, elk, mountain lions,
and moose, as well as the
beautiful giant redwoods of
California. Summers are
temperate, but winters are
long and cold. This biome is
typical of higher elevations
in North America, Europe,
and Asia.
Temperate Deciduous Forest
Deciduous (broadleaf) Forests
are located in the temperate
climate zone below the Coniferous Forest. Most of Europe,
the eastern half of North America,
and parts of Japan, Asia, and
South America were originally
covered by these magnificent
forests of oak and chestnut.
Man has eliminated most of the deciduous forestsclearing land to make room for pastures, farms and towns,
and using the trees up as timber. Most of the Deciduous
Forest has now disappeared. Large animals that once lived
in the Deciduous Forest have almost completely been
driven into the Coniferous Forest.
Chaparral
Chaparral is the dominant
habitat found in southern
California. It is characterized by scrub growth and
small evergreens, lizards,
and coyotes. Because of
hot, dry summers, fires
are common. The old cow
boy movies often took
place in these areas.
The steppes of Eurasia
 The Steppe is a dry, cold,
grassland that is found in all of
the continents except Australia
and Antarctica.
 It is mostly found in the USA,
Mongolia, Siberia, Tibet and
China. Soil is poor
 There isn't much humidity in the
air because Steppe is located
away from the ocean and close
to mountain barriers, usually
between the desert and the
forest. It is often very windy.
 If it got more rain, it would
become a forest. If it got less
rain, it would become a desert.
√Quick Check√
 What two factors determine the type of
biome that exists in an area?
 Name and describe two different biomes
and at what latitudes they would occur.
 What is permafrost and where does it
occur?
 What is the difference between a deciduous
and a coniferous forest and where they
would naturally occur?
QUESTION?
Question. . .
There are about twenty
major deserts on our planet . . .
What single factor do
ALL of these deserts
have in common ?
aridity (dryness)
Although extreme heat is one way to
make a desert dry, at the chilliest
extreme are the polar deserts of
Antarctica and Greenland, where the
frigid air can hold scant moisture,
and what little precipitation there is
comes in frozen form.
desert (not dessert!)
Sahara Desert
Arabian Desert
Western Australian Desert
Middle East
Deserts may be . . .
•Sun-baked sand dunes OR
frozen polar deserts of Antarctica,
•
Snow-swept plateaus OR
cactus-studded mountains,
•Barren salt flats OR
stony mountain sides
desert
 Between 15° and 35°
latitude (N and S of the
equator);
 Examples are Mojave,
Sonoran, Chihuahua, and
Great Basin (North Am.);
Sahara (Africa); Negev (Mid
East); and Gobi (Asia);
 Perennials survive for
several years by becoming
dormant and flourishing
when water is available.
 Annuals are referred to as
ephemerals because some
can complete an entire life
cycle in weeks!
Desert Sidewinder
Sagauro Cactus – up to 50’ tall!
Black-tailed Jack Rabbit
The Great Sahara
The Sahara is the world’s second largest desert,
next to Antarctica. The entire US would fit within
the Sahara! Central and Western Sahara have
high mountains and desert plateaus. The hottest,
most arid region is the Libyan Desert.
West Libyan Desert
Extensive areas of gravel plains like these are called regs.
Sahel of Africa
 The Sahel forms the southern border of the
Sahara and is a transitional area to the savannas.
Beginning in the 1960s, the Sahel has
experienced the problems of drought, overgrazing,
and overpopulation. As a consequence, many
thousands of acres are continuing daily to be lost
to the desert. Hundreds of thousands of people
have faced starvation or have been forced to
move south, exacerbating (intensifying) the
problems of poverty and homelessness.
Nigerois Salt Depressions
Back-bending labor produces salt at Teguidda-n-Tessoumt, a Saharan
village in Niger, where briny well water is mixed with salty earth in
large depressions, then placed in smaller ponds for evaporation.
Pinnacles of Western Australia
Kelso Dunes
Mojave Desert,
California
The American Deserts
The Mojave National Preserve is regarded as the
meeting place for three of the four great American
deserts - the Sonoran, Mojave and Great Basin.
Miners, cattle ranchers, railroad speculators and
wagons westward bound each attempted to
survive here, probably coming by way of a Native
American trail known now as the Mojave Road.
They saw strange volcanic features, towering sand
dunes, and the largest Joshua tree forest in the
world .
Joshua Tree Blooms
Petroglyphs in the Mojave
Meeting of two Dune Crests in a
Dune Field on the Mojave
Death Valley National Park
California
Desolation Canyon
Death
Valley
Badlands
Named features on maps of Death Valley include the
Funeral Mountains, Coffin Peak, Hell's Gate, Dead
Man Pass, and Starvation Canyon - clearly reflecting
the misfortunes endured by pioneers who first traversed, inhabited and mined the region during the end
of the 1800’s.
DEATH VALLEY is a long, low depression set in
largely barren and unpopulated country of
desert plains and rocky ridges, east of the
Sierra Nevada Mountains. Over 130 miles long,
but only around 12 miles wide, it runs roughly
north-south near the California-Nevada border.
From an elevation of 1000 meters at the north
end, the land slopes down steadily and for 70
miles the floor is below sea level, reaching a
low point of -86 meters at Badwater, the lowest
point in the Western hemisphere. The depth of
the depression is partly responsible for the
extreme high temperatures, which can exceed
130°F in summer.
Death Valley
Salt Formations near Badwater
Death Valley
Natural Bridges Rock Formations
Northern Sahara Dune Field
Ergs are great “seas” of sand dunes that cover about a
quarter of the Sahara.
Sahara Dune Field
Late Afternoon
Footprints on the Sands of Time. . .
Oasis
Tafilalt
Oasis,
Morocco
Oases are small fertile areas surrounded by desert,
areas where groundwater lies close enough to the
desert surface that plant roots and wells can reach.
√Quick Check√
 What is the one factor that defines a desert?
 Where is the lowest point in the western
hemisphere? Describe the living conditions.
 What state is home to the largest US
desert?
 What are ergs and regs?
 What is the Sahel? Describe three factors
that are affecting the health of the Sahel and
enlarging the desert even more each year.
Grasslands – Prairies - Savannas
Grassland biomes are large, rolling areas of grasses,
flowers and herbs. Latitude, soil and local climates for the
most part determine what kinds of plants grow in a
particular grassland. A grassland is a region where the
average annual precipitation is great enough to support
grasses, and in some areas a few trees.
Savannas of Northern Australia
The rainy season is from December to March, when there
are heavy thunderstorms and monsoons. Marsupials, such
as pandas and kangaroos, dominate the animal life in this
area and live near the trees for food and protection. In
other parts of the savanna, saltwater crocodiles as long as
24 feet are very common. Remember Crocodile Dundee?
Pampas of South America
Home of the Gauchos, or South American cowboy, the
pampas are found primarily in Argentina and Uruguay.
Again, here are few trees because of the many fires that
destroy their root systems.
Eco-threat
The humid Pampas ecosystem is one of the richest
grazing areas in the world. Because of its
temperate climate and rich, deep soil, most of the
Pampas has been cultivated and turned into
croplands. Unfortunately, domestic livestock and
farming have severely affected the pampas.
Fertilizers and overgrazing are a serious threat to
the pampas. There are only a very few pristine
remnants of the legendary "ocean of grass" that
was the Pampas. It is considered to be one of
the most endangered habitats on earth.
North American Prairie
 The grassland community, or prairie, makes up the
heart and soul of the Great Plains. From the
foothills (or piedmont) of the Rocky Mountains,
where the shortgrass prairie covers the high
plains, to Illinois, where the tallgrass prairie
formerly extended, and from Saskatchewan,
Canada, to Texas, the Prairie dominates the center
of the North American continent.
 Since most of our wheat farms are in this area of
the great Midwest, it is often referred to as the
Breadbasket of the United States.
Prairies of North America
There are extremes of climate, with temperatures ranging as much as
130°F from winter to summer. Annual rainfall varies from 10” on the
high plains to 45”at the edge of the eastern deciduous forest. Weather
systems, such as tornadoes and wind storms, move swiftly across the
flattened Great Plains, carrying cold air from Canada or raising huge
dust storms during the hot, dry summer. There is great biodiversity
and abundance of life. In fact, almost ¾ of bird species in the US breed
on the Grasslands of the Great Plains. Many habitats are endangered.
Savannas of Africa
The savanna is a rolling grassland with few trees that lies between the
desert sahel and the rain forest. Savannas have long, dry winters and
very wet summers, but the temperature is always around 70° F.
In the Serengeti Plains of Tanzania, the grasslands have many acacia
trees and support populations of zebras, lions, giraffes, and
elephants.
√Quick Check√
 In what countries are grasslands found?
Describe how these might differ.
 Where are the grasslands of the US found?
Why is that area called the “breadbasket” of
the country?
 What are some different terms used to
describe the different types of grasslands?
Tropical Rain Forest
The tropical rain forest is a forest of tall trees in a region of
year-round warmth and annual rainfall between 50” and 260”;
thus they are very humid. Temperature varies between 68°
and 93°F. Almost all rain forests lie near the equator.
Rainforests now cover less than 6% of Earth's land surface.
Scientists estimate that more than half of all the world's plant
and animal species live in tropical rain forests. Tropical
rainforests produce 40% of Earth's oxygen.
Rain Forest Biome
Many of the trees have straight
trunks that don't branch out for
100 feet or more, as there is
little light in this area. Most of the
trees have smooth, thin bark
because there is no need to
protect the them from water loss
and freezing temperatures. It
also makes it difficult for epiphytes
(non-parasitic hangers-on!) and
plant parasites to get a hold on
the trunks.
Rain Forest Layering
There are four very distinct layers of trees in a
tropical rain forest:
 emergent – huge trees 100- 240 feet tall that peek
out over the tops of the others;
 upper canopy – trees 60-130 feet tall that use
most of the upper light and provide homes for
most of the forest animals;
 understory - trunks of canopy trees and smaller
trees in a predominately shady and humid area;
 forest floor – thin, poor quality topsoil, very little
light and growth
Our Debt to Rainforests
 The density of species is so great that one hectare
(2.47 acres) may contain over 750 types of trees,
and 1500 other varieties of plants.
 25% of Western pharmaceuticals are derived from
ingredients in the rainforests, yet scientists have
only tested about 1% of the plants in
the forests.
 Indigenous tribes have contributed much
to our knowledge of medicinal value of
the rainforests, and these tribes are being
eradicated as their homes are destroyed.
Did you know. . .
 One and one-half acres of rainforest are lost every
second.
 Rainforests once covered 14% of the earth's land
surface; now they cover only 6%, and experts
estimate that the last remaining rainforests could
be consumed in less than 40 years.
 We are losing 137 plant, animal and insect species
every single day – about 50,000 species per year due to rainforest deforestation. As the rainforest
species disappear, so do many possible cures for
life-threatening diseases.
The Endangered Rainforests
Rain forest
cleared for
soya
production
in Para,
Brazil
A steam winds
through an area
cleared by
loggers in Mato
Grosso, Brazil
√ Quick Check √
 What special contributions do the rainforests
make to our earth?
 What are the four layers of the rain forest?
 What is the meaning of the term
indigenous?
 What factors are threatening the health and
existence of the rain forests?
 In what latitudes are the rain forests found?
The Blue Marble is truly the
Blue Marvel!
Each of us has the responsibility to be a
good custodian (caretaker) of our Earth:
– By not polluting, carelessly littering, and
trashing our community and roadways;
– By not wasting water, electricity, food, fuel, and
other precious resources;
– By not using or buying more than we need;
– By understanding that each individual must help
to keep our Earth healthy, beautiful, and
productive for the generations that come after
us.
This we know ...
The earth does not belong to man;
man belongs to the earth.
All things are connected like the
blood that unites one family.
Man did not weave the web of life;
he is merely a strand in it.
Whatever he does to the web, he
does to himself.
American Indian Credo