Chapter One – Fire and Ice
The large continents of North America andSouth America are located in the WesternHemisphere. The United States of America issituated within North America. Canada is ourneighbor to the north. Our neighbor to the southis Mexico.
The United States of America is home to 50
states and the District of Columbia. As a 21stcentury resident of Washington and the UnitedStates 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 ofthe United States known as the Pacific Northwest.
The Pacific Northwest includes the states of
Washington, Oregon, and Idaho. The Canadianprovince of British Columbia is our neighbor tothe north. Washington’s southern neighbor isthe state of Oregon. The Pacific Ocean serves asthe western boundary. Lying east of Washingtonis the state of Idaho.
Washington is a medium-sized state thatcovers just over 70,000 square miles. Washingtonis one of the smallest states west of the MississippiRiver. Did you know Washington is larger thanany state east of the Mississippi River?
Washington measures 370 miles from east towest. It is 240 miles between the northern andsouthern borders.
For hundreds of thousands of yearsWashington was void of humans. Only recentlyhave humans settled and lived here.
Archaeologists estimate that humans have lived
in the area for at least the last 14,000 years. Todayour state's population exceeds six million people.Washingtonians have always depended on thearea's natural landscape. Many, in fact, dependon it for their survival!
Why is our landscape so critical to our way of
life and survival? What created our state’s diverselandscape? How do these forces work? Are theystill at work today? We will explain the answersto these questions and more. Let us begin withthe forces that created our landscape.
Geologic Time
Earth’s age is approximately five billion years
old. Humans are believed to have lived on Earthfor only the past six million years. Six millionyears is less than eight hundredths of one percent(8/100) of five billion years! To put this inperspective, it would be like using the 24 hoursof a clock to represent Earth's history with eachsecond representing a year. The total number of
seconds (86,400) per day would represent fivebillion years. Humans have lived on Earth foronly 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 thelandscape of Washington. In fact, plate activityis just as common now as ever before. Millions ofyears ago, waves from the Pacific Ocean oncecrashed against the western edge of the RockyMountains. This means that where you now livewas once an ocean sea floor. The North American Plate continued to move west. As a result, thewestern portion of North America began to
change.
A smaller oceanic plate played a big role in
changing western Washington. We refer to it asthe Juan de Fuca Plate. As it moved under theNorth American Plate, it pushed the lightercontinental plate upward. Mountains rose whereonce an ocean teamed with life. Volcanic peakserupted 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 hundredsof miles away. Then vast sheets of ice coveredand 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 ofcrust movement usually occurs on the oceanfloor. It is the result of the Earth's crust pullingapart from a central ridge.
Transformant movement occurs when two
plates collide. This collision produces either asliding or slipping action. This is happening onthe famous San Andreas fault in California.Another type of ransformant movement is whentwo continental plates collide. This is happeningin Asia. The Himalayaswere formed by this typeof plate movement.
The last type of crust movement isconvergence. Convergence is when two giantplates 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 itpicks up landforms such as islands and riverdeltas. This adds weight to the leading edge ofthe plate. The additional weight slows the landbehind the leading edge. The weight causes thecontinental 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 AmericanPlate is forcing the heavier Juan de Fuca Plate
into the mantle. The heavy oceanic plate isalways pushed into the mantle. The oceanicplate also melts as it sinks. The melted rockrises through cracks in the crust above tocreate volcanoes. Volcanoes are just one of
many processes used to release the pressurewithin Earth's crust. All this is happeningbeneath our state. Isn’t it amazing!
Volcanoes
The most visible natural force affectingWashington is volcanic activity. The most recentvolcanic eruption in the Cascades happened inthe spring of 1980. Before the eruption of MountSt. Helens, many scientists were excited aboutthe renewed rumblings of Washington's volcano.
There were also concerns about the potential
damages an eruption could cause. How rightthey were to be excited and concerned!
Mount Saint Helens
Before her eruption, Mount Saint Helenswas one of the most beautiful volcanoes in theworld. Mount Fuji in Japan is also a volcano ofsimilar beauty. On the morning of May 18, 1980,Mount Saint Helens drastically changed herappearance in the blink of an eye.
Mount Saint Helens violently awoke from
her nap. Geologically speaking, her nap wasshort — only a hundred years or so. Mostvolcanoes experience much longer periodsbetween eruptions. When a volcano is inactive,it is said to be dormant. Dormancy is the wordused to describe the time between eruptions.Mount Saint Helensended her dormancy ona beautiful Sunday morning. The blue skiesdarkened when an earthquake triggered alandslide on the mountain's north face. The entirenorth face of the mountain instantly slid into theNorth Fork of the ToutleRiver. Internal pressure
that had been increasing for two monthssuddenly was released. The eruption blew acolumn 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 themountain’s melted snow and ice rushed into therivers carrying rocks, trees, and mud. Windrushed outward snapping trees and leveling theforest for miles. Wind, high in the atmosphere,also pushed the rising ash east. Cities such asYakima, Wenatchee, and MosesLake werecovered in ash as day turned into night!
Mount Saint Helens’ shape was instantlychanged. Her nearly perfect volcanic cone wasgone. Only a barren horseshoe crater was leftbehind as a reminder of what had been. Mudand debris clogged rivers in southwesternWashington. An unknown number of plantsand animals were killed. In addition, 57 peoplelost their lives.
There are many areas in southwesternWashington where you can see and learn aboutthe devastation of Mount Saint Helens. One isthe Johnston Ridge Observatory. There you willgain an appreciation of nature’s power to destroyand create. Years after the eruption, plants andanimals are reclaiming their land. You shouldvisit Mount Saint Helens. It is a trip definitelyworth your time!
Dormant Volcanoes
Mount Saint Helens’ eruption created a worldwideinterest in our dormant volcanic peaks. Thosewho live near dormant volcanoes now keep awatchful eye on any activity. As discussed earlier,dormant volcanoes are inactive, or sleeping.Northwest volcanic peaks, such as Mount Rainier,Mount Baker, and MountAdams 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 havebeen a walk in the park.
Earlier inhabitants witnessed eruptions of
these dormant volcanoes. Native Americanfolklore and eyewitness accounts described theseeruptions. Today, we are wise to learn as muchabout volcanoes as possible. Hopefully we willbe informed to better prepare ourselves for futureeruptions.
One example of past eruptions is the Native
American story of the Love Triangle. Theirfolklore tells about the battle for the love ofLoowit. The conflict was between Klickitat(MountAdams) and Oregon’s Wy’east (MountHood). They competed for Loowit’s love. As thestory goes, Loowit was once a black, ugly witchwho turned into a lovely “Lady of Fire.” Do you
know which volcano the Native Americans calledLoowit? If you guessed Mount Saint Helens,your are correct. Do you think the lovely maidenturned back into the black ugly witch on May 18,1980?
The entire 600 miles of the CascadeMountains were once extremely active.Continuous volcaniceruptions have built anddestroyed the volcanoes. A few destructivevolcanic eruptions greatly changed the height
and shape of both Mount Rainier and MountSaint Helens. Most of the volcanic eruptionsoccurred long before humans lived inWashington. An eruption long ago covered mostof 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 eruptionthat created the second largest basalt plateau inthe world — the Columbia Plateau. As lava coolsit hardens into a type of rock called basalt.
Basalt covers much of eastern Washingtonand Oregon. This area is called the ColumbiaPlateau. The plateau was formed over millionsof years. The land between the Rocky andCascade mountains was compressed andcracked. This created fissures. These large fissuresallowed lava to erupt and flow in every direction.
More than 55 lava flows cover the Columbia
Plateau. Today, scientists estimate that the basaltmay be thousands of feet thick. If you are evernear theColumbia River you can see just a few ofthe 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 naturalbeauty and interesting scenery to the heat andpressure beneath us. Eruptions in Washingtonwill continue in the future. We all must realizethat we live in the Ring of Fire.
Ring of Fire
Volcanic eruptions and earthquakes are verycommon around the Pacific Ocean. This area iscalled the Ring of Fire. The name comes from themany volcanoes and active faults that dominatethe area.
One of the largest eruptions in recent historyhappened in the Ring of Fire on June 12, 1991.The eruption of the Philippine's Mount Pinatubobegan with a massive blast. A volcanic plumewas pushed more than 11 miles into the sky. Theeruption continued for three days. On the thirdday, a final eruption occurred that was sopowerful it destroyed the entire mountain! Theheat from the eruption pushed the ash plumemore than 25 miles into the atmosphere. The ashwent so high that the wind carried it around theentire planet!
The eruption released so much ash andmaterial into the air that it blocked some of theenergy from the sun. The average dailytemperature of Earth dropped by one full degreethe following year.Besides its powerful volcanic eruptions, theRing of Fire is also known for its earthquakes.
Kobe, Japan was recently devastated by one of
these earthquakes. Of course this earthquakeoccurred in the Ring of Fire. Kobe-Osaka isJapan’s second-most populated area next toTokyo. The city of Kobe is Seattle's sister city.Little did residents of Kobe know how their liveswould change in just 20 seconds.On Tuesday, January 17, 1995 at 5:46am, anearthquake of 7.2 magnitude on the Richter scalestruck the region of Kobe and Osaka. The shallowshock occurred on a fault running from AwajiIsland through the city of Kobe. Strong groundmovement lasted for about 20 seconds. The Kobeearthquake caused severe damage tobuildings,homes, and freeways over a large area.The number of injured reached about 35,000.Nearly 5,500 deaths were confirmed. Some180,000 buildings were badly damaged ordestroyed. Officials estimate that more than300,000 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 crustis suddenly and violently released. This energyis usually released from a single point. Thispoint is known as the epicenter.Earthquakes can occur along active faults in
Earth’s crust. Faults occur when two differentplates of crust touch. These faults grind andmove slowly against each other. Sometimes thesefaults get stuck. They can remain stuck fordecades or even centuries. Finally, the pressurebecomes so great that the rock holding the platessuddenly 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 9.2on the Richter scale. Anchorage, Alaska was thelocation of the quake’s epicenter. Residentsreported strong ground movement for four tofive minutes! Compare four to five minutes to
the 20 or 30 seconds of severe ground movementin the Kobe earthquake! The ground in someparts of Alaska was uplifted more than 30 feet ina matter of seconds. Interestingly, more peoplewere hurt from the tidal wave than from theearthquake.
When faults store energy for such longperiods, earthquakes like the one in Alaska willhappen. Thankfully, earthquakes like this donot happen that often.Over the past 50 years, Washington residents
have experienced three major damagingearthquakes. The most recent earthquake ofFebruary 28, 2001 measured 6.8 on the Richterscale. The epicenter of the earthquake was nearOlympia. In contrast to the Alaskan quake of1964, our earthquake had severe ground
movement lasting only 30 to 40 seconds. Theearthquake was felt as far away as Utah andBritish Columbia, Canada. Thankfully, thedamage was mostly minor.
Seismologists from around the world havepredicted a large earthquake in Washington.They estimate that it will measure between eightand nine on the Richter scale. Most agree that itwill occur in the near future. And earthquake thissize would be extremely damaging toWashington and the Pacific Northwest.
Ice Age
Earthquakes and volcanic eruptions are notthe only forces forming our landscape. Ice hasbeen a major factor in our landscapes formation.The last major ice age was a rather recent geologicevent. It ended about 10,000 years ago. Duringthe last ice age, continental glaciers advanced asfar south as Olympia and the Columbia River in
northeastern Washington.
Glaciers are formed when snow packs never
completely melt. Over time, the snow pack getsdeeper and heavier from new snowfall. Snow iscompressed by its own weight. Weight changesthe structure of the snow. Snow crystals willstart to fit tightly together to form layers of ice.As this ice thickens, its weight increases changingthe layers into a solid mass of ice. Gravity beginsto move the thickening mass. At the point atwhich it begins to move, it then becomes a glacier.
Smaller glaciers can even combine to formlarger continental glaciers. These glaciers aregiant sheets of ice moving across the surface ofEarth. They change everything in their path.
These continental glaciers helped create the
landscape of Washington.During periodic ice ages, huge continentalglaciers advanced southward from Canada.
Three different lobes of ice pushed intoWashington. The three lobes were the Puget,Okanogan, and Polson. The southern edges ofthese lobes were thousands of feet thick. Erosionand scarring resulted from the movement ofthese 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 FraserRiverValley in Canada. It flowedbetween the Olympic and Cascade mountains.The lobe advanced as far south as what is nowOlympia. As the ice moved, its tremendousweight depressed western Washington. Most ofnorthwestern Washington was covered withthick continental ice. Only the higher mountainsremained. Western Washington remainedcovered in ice forthousands of years.
Glaciers are large conveyer belts of ice. They
easily carry everything in their path, includingtrees, rocks, dirt, and huge boulders. The materialthey carry is called glacial till.As the climate began to warm, the PugetLobe gradually melted. Since it was so large, the
melting took hundreds, if not thousands, of years.When glaciers melt they stall and deposit largeamounts of glacial till at the leading edge. Thisdebris formed many of our islands and hills inwestern Washington. The sheer weight of theglacier also carved our deep waterways. Theseprotected waterways provide Washington withexcellent shipping harbors.