Download Chapter One – Fire and Ice

Chapter One – Fire and Ice
The large continents of North America and
South America are located in the Western Hemisphere.
The United States of America is situated within North
America. Canada is our neighbor to the north. Our
neighbor to the south is Mexico.
The United States of America is home to 50
states and the District of Columbia. As a 21st century
resident of Washington and the United States of
America, we should feel very fortunate.
As American citizens we enjoy a comfortable
and secure life in this great nation. Washington is
located in a small region of the United States known as
the Pacific Northwest.
The Pacific Northwest includes the states of
Washington, Oregon, and Idaho. The Canadian province
of British Columbia is our neighbor to the north.
Washington’s southern neighbor is the state of Oregon.
The Pacific Ocean serves as the western boundary.
Lying east of Washington is the state of Idaho.
Washington is a medium-sized state that covers just over
70,000 square miles. Washington is one of the smallest
states west of the Mississippi River. Did you know
Washington is larger than any state east of the
Mississippi River?
Washington measures 370 miles from east to west. It is
240 miles between the northern and southern borders.
For hundreds of thousands of years Washington was
void of humans. Only recently have humans settled and
lived here.
Archaeologists estimate that humans have lived
in the area for at least the last 14,000 years. Today our
state's population exceeds six million people.
Washingtonians have always depended on the area's
natural landscape. Many, in fact, depend on it for their
survival!
Why is our landscape so critical to our way of
life and survival? What created our state’s diverse
landscape? How do these forces work? Are they still at
work today? We will explain the answers to these
questions and more. Let us begin with the forces that
created our landscape.
Geologic Time
Earth’s age is approximately five billion years
old. Humans are believed to have lived on Earth for only
the past six million years. Six million years is less than
eight hundredths of one percent (8/100) of five billion
years! To put this in perspective, it would be like using
the 24 hours of a clock to represent Earth's history with
each second representing a year. The total number of
seconds (86,400) per day would represent five billion
years. Humans have lived on Earth for only 72 of those
seconds, or just over one-minute.
Washington residents have only witnessed
2/10ths of one second of our “history clock.” How has our
physical environment changed?
Plate movement has greatly affected the
landscape of Washington. In fact, plate activity is just as
common now as ever before. Millions of years ago,
waves from the Pacific Ocean once crashed against the
western edge of the Rocky Mountains. This means that
where you now live was once an ocean sea floor. The
North American Plate continued to move west. As a
result, the western portion of North America began to
change.
A smaller oceanic plate played a big role in
changing western Washington. We refer to it as the Juan
de Fuca Plate. As it moved under the North American
Plate, it pushed the lighter continental plate upward.
Mountains rose where once an ocean teamed with life.
Volcanic peaks erupted and covered the land with ash
and lava.
The area between the Rockies and the Cascades
cracked and allowed lava to flow over the area. Rivers
filled with water from melted snow. Flooded rivers
flowed to the ocean now hundreds of miles away. Then
vast sheets of ice covered and scarred the lower
elevations.
Plate Movement
Earth’s crust moves in three different ways.
Plate movement occurs in either a divergent,
transformant, or convergent fashion. Divergence
is when two giant plates pull apart. This type of crust
movement usually occurs on the ocean floor. It is the
result of the Earth's crust pulling apart from a central
ridge.
Transformant movement occurs when two
plates collide. This collision produces either a sliding or
slipping action. This is happening on the famous San
Andreas fault in California. Another type of
ransformant movement is when two continental plates
collide. This is happening in Asia. The Himalayas were
formed by this type of plate movement.
The last type of crust movement is convergence.
Convergence is when two giant plates meet and one is
forced under the other. Convergence is happening
beneath Washington.
Over millions of years, the North American
Plate has slowly moved west. Along its way it picks up
landforms such as islands and river deltas. This adds
weight to the leading edge of the plate. The additional
weight slows the land behind the leading edge. The
weight causes the continental plate to tilt, uplift, and fold
the crust.
This exact force is forming the Cascade
Mountains. The Cascades are the major landform
in Washington. This added weight on the North
American Plate is forcing the heavier Juan de Fuca Plate
into the mantle. The heavy oceanic plate is always
pushed into the mantle. The oceanic plate also melts as it
sinks. The melted rock rises through cracks in the crust
above to create volcanoes. Volcanoes are just one of
many processes used to release the pressure within
Earth's crust. All this is happening beneath our state.
Isn’t it amazing!
Volcanoes
The most visible natural force affecting
Washington is volcanic activity. The most recent
volcanic eruption in the Cascades happened in the spring
of 1980. Before the eruption of Mount St. Helens, many
scientists were excited about the renewed rumblings of
Washington's volcano.
There were also concerns about the potential
damages an eruption could cause. How right they were
to be excited and concerned!
Mount Saint Helens
Before her eruption, Mount Saint Helens was
one of the most beautiful volcanoes in the world. Mount
Fuji in Japan is also a volcano of similar beauty. On the
morning of May 18, 1980, Mount Saint Helens
drastically changed her appearance in the blink of an
eye.
Mount Saint Helens violently awoke from
her nap. Geologically speaking, her nap was short —
only a hundred years or so. Most volcanoes experience
much longer periods between eruptions. When a volcano
is inactive, it is said to be dormant. Dormancy is the
word used to describe the time between eruptions.
Mount Saint Helens ended her dormancy on a beautiful
Sunday morning. The blue skies darkened when an
earthquake triggered a landslide on the mountain's north
face. The entire north face of the mountain instantly slid
into the North Fork of the Toutle River. Internal pressure
that had been increasing for two months suddenly was
released. The eruption blew a column of ash more than
80,000 feet into the sky.
Within thirty seconds, 1,300 feet of Mount
Saint Helens' peak was gone. Water from the mountain’s
melted snow and ice rushed into the rivers carrying
rocks, trees, and mud. Wind rushed outward snapping
trees and leveling the forest for miles. Wind, high in the
atmosphere, also pushed the rising ash east. Cities such
as Yakima, Wenatchee, and Moses Lake were covered in
ash as day turned into night!
Mount Saint Helens’ shape was instantly
changed. Her nearly perfect volcanic cone was gone.
Only a barren horseshoe crater was left behind as a
reminder of what had been. Mud and debris clogged
rivers in southwestern Washington. An unknown
number of plants and animals were killed. In addition,
57 people lost their lives.
There are many areas in southwestern
Washington where you can see and learn about the
devastation of Mount Saint Helens. One is the Johnston
Ridge Observatory. There you will gain an appreciation
of nature’s power to destroy and create. Years after the
eruption, plants and animals are reclaiming their land.
You should visit Mount Saint Helens. It is a trip
definitely worth your time!
Dormant Volcanoes
Mount Saint Helens’ eruption created a
worldwide interest in our dormant volcanic peaks. Those
who live near dormant volcanoes now keep a watchful
eye on any activity. As discussed earlier, dormant
volcanoes are inactive, or sleeping. Northwest volcanic
peaks, such as Mount Rainier, Mount Baker, and Mount
Adams are all dormant.
These volcanoes may be dormant, but do not let
them fool you! If any of these volcanoes awaken, Mount
Saint Helens’ eruption may prove to have been a walk in
the park.
Earlier inhabitants witnessed eruptions of
these dormant volcanoes. Native American folklore and
eyewitness accounts described these eruptions. Today,
we are wise to learn as much about volcanoes as
possible. Hopefully we will be informed to better
prepare ourselves for future eruptions.
One example of past eruptions is the Native
American story of the Love Triangle. Their folklore tells
about the battle for the love of Loowit. The conflict was
between Klickitat (Mount Adams) and Oregon’s
Wy’east (Mount Hood). They competed for Loowit’s
love. As the story goes, Loowit was once a black, ugly
witch who turned into a lovely “Lady of Fire.” Do you
know which volcano the Native Americans called
Loowit? If you guessed Mount Saint Helens, your are
correct. Do you think the lovely maiden turned back into
the black ugly witch on May 18, 1980?
The entire 600 miles of the Cascade Mountains
were once extremely active. Continuous volcanic
eruptions have built and destroyed the volcanoes. A few
destructive volcanic eruptions greatly changed the height
and shape of both Mount Rainier and Mount Saint
Helens. Most of the volcanic eruptions occurred long
before humans lived in Washington. An eruption long
ago covered most of the Pacific Northwest in lava. The
lava, however, did not come from a volcano. It flowed
from giant cracks, or fissures, in the crust.
Other Volcanic Activity
Plate movement also causes cracks, called
fissures, in the crust of Earth. These fissures allow
magma to flow. This is the type of eruption that created
the second largest basalt plateau in the world — the
Columbia Plateau. As lava cools it hardens into a type of
rock called basalt.
Basalt covers much of eastern Washington and
Oregon. This area is called the Columbia Plateau. The
plateau was formed over millions of years. The land
between the Rocky and Cascade mountains was
compressed and cracked. This created fissures. These
large fissures allowed lava to erupt and flow in every
direction.
More than 55 lava flows cover the Columbia
Plateau. Today, scientists estimate that the basalt may be
thousands of feet thick. If you are ever near the
Columbia River you can see just a few of the layers in
the cliff walls. It is clear that volcanic activity has
changed, and will continue to change, our landscape.
Obviously we owe much of Washington's natural beauty
and interesting scenery to the heat and pressure beneath
us. Eruptions in Washington will continue in the future.
We all must realize that we live in the Ring of Fire.
Ring of Fire
Volcanic eruptions and earthquakes are very
common around the Pacific Ocean. This area is called
the Ring of Fire. The name comes from the many
volcanoes and active faults that dominate the area.
One of the largest eruptions in recent history happened
in the Ring of Fire on June 12, 1991. The eruption of the
Philippine's Mount Pinatubo began with a massive blast.
A volcanic plume was pushed more than 11 miles into
the sky. The eruption continued for three days. On the
third day, a final eruption occurred that was so powerful
it destroyed the entire mountain! The heat from the
eruption pushed the ash plume more than 25 miles into
the atmosphere. The ash went so high that the wind
carried it around the entire planet!
The eruption released so much ash and material
into the air that it blocked some of the energy from the
sun. The average daily temperature of Earth dropped by
one full degree the following year. Besides its powerful
volcanic eruptions, the Ring of Fire is also known for its
earthquakes.
Kobe, Japan was recently devastated by one of
these earthquakes. Of course this earthquake occurred in
the Ring of Fire. Kobe-Osaka is Japan’s second-most
populated area next to Tokyo. The city of Kobe is
Seattle's sister city. Little did residents of Kobe know
how their lives would change in just 20 seconds. On
Tuesday, January 17, 1995 at 5:46am, an earthquake of
7.2 magnitude on the Richter scale struck the region of
Kobe and Osaka. The shallow shock occurred on a fault
running from Awaji Island through the city of Kobe.
Strong ground movement lasted for about 20 seconds.
The Kobe earthquake caused severe damage to
buildings, homes, and freeways over a large area. The
number of injured reached about 35,000. Nearly 5,500
deaths were confirmed. Some 180,000 buildings were
badly damaged or destroyed. Officials estimate that
more than 300,000 people were homeless on the night of
theearthquake. All this damage was caused by only
20 seconds of shaking ground!
Earthquakes
Earthquakes occur when energy in the crust is
suddenly and violently released. This energy is usually
released from a single point. This point is known as the
epicenter. Earthquakes can occur along active faults in
Earth’s crust. Faults occur when two different plates of
crust touch. These faults grind and move slowly against
each other. Sometimes these faults get stuck. They can
remain stuck for decades or even centuries. Finally, the
pressure becomes so great that the rock holding the
plates suddenly gives way. When it does, the plates
suddenly move. The sudden movement of the
two plates causes the ground to shake or quake.
This is an earthquake.
The largest earthquake ever recorded in
North America happened in Alaska in 1964. Alaska's
earthquake measured a whopping 9.2 on the Richter
scale. Anchorage, Alaska was the location of the quake’s
epicenter. Residents reported strong ground movement
for four to five minutes! Compare four to five minutes to
the 20 or 30 seconds of severe ground movement in the
Kobe earthquake! The ground in some parts of Alaska
was uplifted more than 30 feet in a matter of seconds.
Interestingly, more people were hurt from the tidal wave
than from the earthquake.
When faults store energy for such long periods,
earthquakes like the one in Alaska will happen.
Thankfully, earthquakes like this do not happen that
often. Over the past 50 years, Washington residents
have experienced three major damaging earthquakes.
The most recent earthquake of February 28, 2001
measured 6.8 on the Richter scale. The epicenter of the
earthquake was near Olympia. In contrast to the Alaskan
quake of 1964, our earthquake had severe ground
movement lasting only 30 to 40 seconds. The earthquake
was felt as far away as Utah and British Columbia,
Canada. Thankfully, the damage was mostly minor.
Seismologists from around the world have predicted a
large earthquake in Washington. They estimate that it
will measure between eight and nine on the Richter
scale. Most agree that it will occur in the near future.
And earthquake this size would be extremely damaging
to Washington and the Pacific Northwest.
Ice Age
Earthquakes and volcanic eruptions are not the
only forces forming our landscape. Ice has been a major
factor in our landscapes formation. The last major ice
age was a rather recent geologic event. It ended about
10,000 years ago. During the last ice age, continental
glaciers advanced as far south as Olympia and the
Columbia River in
northeastern Washington.
Glaciers are formed when snow packs never
completely melt. Over time, the snow pack gets deeper
and heavier from new snowfall. Snow is compressed by
its own weight. Weight changes the structure of the
snow. Snow crystals will start to fit tightly together to
form layers of ice. As this ice thickens, its weight
increases changing the layers into a solid mass of ice.
Gravity begins to move the thickening mass. At the point
at which it begins to move, it then becomes a glacier.
Smaller glaciers can even combine to form larger
continental glaciers. These glaciers are giant sheets of
ice moving across the surface of Earth. They change
everything in their path.
These continental glaciers helped create the
landscape of Washington. During periodic ice ages, huge
continental glaciers advanced southward from Canada.
Three different lobes of ice pushed into Washington.
The three lobes were the Puget, Okanogan, and Polson.
The southern edges of these lobes were thousands of feet
thick. Erosion and scarring resulted from the movement
of these glaciers. It is very easy to see how drastically
Washington's landscape has been affected by
continental ice. Though the ice melted long ago,
the scars they left are everywhere.
Puget Lobe
The Puget Lobe began its march south from
the Fraser River Valley in Canada. It flowed between the
Olympic and Cascade mountains. The lobe advanced as
far south as what is now Olympia. As the ice moved, its
tremendous weight depressed western Washington. Most
of northwestern Washington was covered with thick
continental ice. Only the higher mountains remained.
Western Washington remained covered in ice for
thousands of years.
Glaciers are large conveyer belts of ice. They
easily carry everything in their path, including trees,
rocks, dirt, and huge boulders. The material they carry is
called glacial till. As the climate began to warm, the
Puget Lobe gradually melted. Since it was so large, the
melting took hundreds, if not thousands, of years. When
glaciers melt they stall and deposit large amounts of
glacial till at the leading edge. This debris formed many
of our islands and hills in western Washington. The
sheer weight of the glacier also carved our deep
waterways. These protected waterways provide
Washington with excellent shipping harbors.
Okanogan Lobe
The Okanogan Lobe was another portion of the
continental ice sheet that moved south into northern
Washington. The lobe advanced as far south as the
Columbia Basin near Grand Coulee. When the ice
reached the Columbia Basin, it blocked the natural
course of the Columbia River.
A dam of ice was formed. As the water rose
behind the dam, it flooded the Columbia Basin. The
water rushed south, eventually spilling over Dry Falls.
This process of glacial flooding continued over
thousands of years.
At that time Dry Falls was anything but dry.
It was one of the largest waterfalls in the world. The
water rushing over the Columbia Basin dropped
hundreds of feet. Dry Falls was once more than 40 times
larger than Niagara Falls. Niagara Falls was also formed
by the last ice age. Unlike Dry Falls, it still has water
rushing over its cliffs today. This constant flooding
eroded and scarred the Columbia Basin. These scars are
deeply eroded valleys called coulees and are present
today. They truly are impressive sites to see! The most
spectacular remnant of the glacial flooding is Dry Falls.
About 10,000 to 15,000 years ago, the
Okanogan Lobe began melting. As the lobe melted, the
Columbia River burst through the remaining ice. Now
that the ice dam was gone, the Columbia River could
again flow to the sea on its natural course. When the ice
dam broke, the floodwater spilling over the edge of the
falls finally stopped. Dry Falls was once again dry.
The lobe continued melting. As the glacial ice melted, it
created the river valleys of the Okanogan Highlands.
However, the Polson Lobe was not to be outdone by
either the Puget or Okanogan lobes.
Polson Lobe
The Polson Lobe was the third lobe of
continental ice to invade the region. As the lobe moved
south, it blocked the rivers of western Montana, northern
Idaho, and northeastern Washington. Unlike the water
behind the ice dam that blocked the Columbia River, this
water had no place to go. A huge glacial lake, the
combined size of the Great Lakes, Erie and Ontario,
formed behind the ice dam. This lake is now known as
Glacial Lake Missoula. The ice dams collapsed nearly
every two to three decades. When it finally did collapse,
it released a wall of water estimated to be 400 feet
deep. It traveled at a speed of an estimated 65 miles an
hour across the Columbia Basin. The erosive force of the
water left scars on everything it touched. These scars are
what we now call the coulees and Channeled Scablands.
As the water reached the Wallula Gap the
flow of water was slowed. The narrow gap acted like a
natural dam. The water then filled the area behind the
gap. The new lake slowly drained through the gap and
continued to the ocean. This process continued for
thousands of years during the last ice age. The amount of
water released by Glacial Lake Missoula was amazing. It
was equal to more than ten times the combined flow of
all the rivers in the world! At that rate, the lake would
have drained in less than 48 hours!
Other Forces of Ice
Alpine glaciers and avalanches continue to erode
the slopes of Washington's volcanoes and mountains.
Both forms of ice and snow scar the landscape.
Avalanches release a sudden burst of destruction. Alpine
glaciers are more destructive but much, much slower.
Alpine glaciers are common in the higher Cascade and
Olympic mountains. Mount Rainier has 26 alpine
glaciers covering its slopes.
Two other glacial creations are Lake Chelan
and the Palouse Hills. Lake Chelan is our state's largest
and deepest natural lake. It is more than 1,486 feet deep!
In contrast, the dry farmland of the Palouse Hills of
southeastern Washington and western Idaho were
formed by wind blown silt. The silt that formed the hills
was left behind by glacial floods. This area is known for
its landscape of gently rolling hills.
Wind from the Pacific Ocean picked up and
carried very fine particles of glacial till. The soil was
blown east until it reached the foothills of the Rocky and
Blue mountains. The mountains slowed the wind, and
the soil was deposited over thousands of years. Today,
the Palouse Hills are extremely fertile because of this
soil.
When you look closely, it is easy to see the
effects of glaciers everywhere in our state. Some of our
northern mountain valleys are scarred. Islands and
peninsulas are reminders of continental ice sheets.
Mountains and volcanic peaks are blanketed year round
in snow and ice.
Some of the most fertile farmland in the world
was even created from ice and wind. These erosive
forces obviously have the ability to destroy. However, it
is easy to see how they create at the same time. Think of
them as Mother Nature's magic paintbrush!
Summary
Today, within the state of Washington, there
are many visual reminders of the past. Volcanic peaks,
mountain ranges, and a plateau are just a few reminders
of Earth's internal violence. Scars in our landscape have
been scoured by ice, water, and wind. Washington's
numerous physical features are all visual reminders of
the power of ice, water, and wind. The next time you see
these landforms, you will better appreciate how Earth's
fire and ice created and shaped our land. These natural
forces are still changing our beautiful landscape.