Chapter 2
Washington has a diverse natural
environment. The Cascade Mountains divide the state
into two extremely different natural environments.
Those areas west of the Cascades have a mild and
moist climate. This moist climate allows dense
forests and vegetation to grow.
The areas east of the Cascades, in contrast,
have a harsh and dry climate. This dry climate allows
mostly short grasses and sagebrush to grow. Drive
over the mountain passes and you can very easily see
the contrasts between western and eastern
Washington. Contrasts are evident throughout the
state of Washington. The saltwater environment of
our bays, inlets, and harbors is different from the
freshwater environment of Washington’s lakes and
rivers. Hundreds of small rivers and streams do not
compare in size to the Columbia River.
Our land changes quickly from the flat
floodplains in the valleys to the tall mountain peaks
and volcanoes. Low, rounded hills differ greatly from
the towering jagged cliffs of the North Cascades. The
huge Columbia Plateau easily dominates the much
smaller Waterville Plateau. Hundreds of our small
islands do not compare in size to Whidbey Island, the
second largest island in the lower 48 states.
Numerous peninsulas cannot compare in size to the
Olympic Peninsula. All these contrasts in our state
make for an amazingly diverse natural environment.
In this chapter, we will focus on physical
features and how they affect the natural environment
of Washington. Geologists classify landforms into
five different categories: mountains, hills, plateaus,
plains, and river valleys. Landforms, no matter the
type, are constantly eroded by the forces of nature.
As was discussed in Chapter One, volcanic activity,
glaciation, and erosion have changed and shaped
Washington’s physical terrain.
Physical Terrain
The physical terrain in Washington is
diverse. There is very little level land and several
mountain ranges. Elevations in the state range from
sea level to 14,411 feet at Mount Rainier. Mountains,
the first landform we will discuss, are obviously the
easiest of the five to recognize.
Mountains
The state of Washington has several
mountainous landforms. There are five major
mountain groups. The first and largest of the
mountain ranges is the Cascades. A smaller group of
mountains is the Olympics on the
Olympic Peninsula. The third largest group of
mountains, the Rockies, can be found on the eastern
border of Washington. The Blue Mountains in
southeastern Washington make up the fourth group.
The Okanogan Highlands of north central
Washington are the final and smallest group. Of these
five major groups, only the Olympics are located
totally within the state of Washington. The other
mountains also rise into neighboring states and
Canadian provinces. Of the five groups, the Cascade
Mountains have the largest impact on our natural
environment.
Cascades
The Cascade Mountains are the most
significant range in our state. They extend 600
miles south from British Columbia through
Washington and Oregon into northern California.
Many of the Cascade peaks rise to an elevation of
5,000 to 8,000 feet above sea level.
Several volcanic peaks rise even higher.
Washington’s tallest volcanic peak is Mount Rainier.
It has an elevation of 14,411 feet and is the largest
volcano in the Cascade Range. Four other volcanoes
surround it, two are situated to the north and two to
the south. The largest of the southern volcanoes is
Mount Adams with an elevation of 12,307 feet. Forty
miles west of it is the smallest of our volcanoes,
Mount Saint Helens. On May 18, 1980, when Mount
St. Helens erupted, it instantly lost 1,312 feet of its
peak. The peak of Mount St. Helens now only rises
8,365 feet above sea level.
The scenic volcanic peak of Mount Baker is
100 miles to the north of Mount Rainier. Mount
Baker has an elevation of 10,778 feet. The least
known volcano in Washington is Glacier Peak.
Glacier Peak is a beautiful mountain located just west
of Lake Chelan. It stands 10,434 feet above sea level
and is the oldest of our volcanic peaks.
The Cascade Mountains are our state’s most
significant barrier. This chain of mountains divides
Washington into two natural environments. These
regions are western and eastern Washington. As
discussed earlier, western Washington has a mild and
moist climate compared to eastern Washington. The
Cascade Mountains form a physical barrier to
moisture blowing in from the Pacific Ocean. This
barrier creates a rainshadow effect . The Cascade
Mountains also present a physical barrier to travel,
especially during the winter season. Travel is difficult
over the mountains because of the high elevations
and heavy winter snow.
The most frequently traveled mountain
passes are Snoqualmie and Stevens. These mountain
passes are often closed in winter for avalanche
control and snow removal. Several other less traveled
mountain passes are closed for most of the winter
because snow removal is too difficult.
The towering snow-capped peaks make the
Cascade Mountains a scenic drive any time of the
year. Another scenic mountain range in Washington
is the Olympics.
Olympics
The Olympic Mountains form the large
peninsula of western Washington. A peninsula is an
area of land surrounded by water on three sides. The
Pacific Ocean surrounds the Olympic Peninsula to
the west. The northern extent of the peninsula is the
Strait of Juan de Fuca. Water from the Pacific Ocean
fills Hood Canal, which forms the eastern boundary
of the Olympic Peninsula. These young and rugged
mountains used to be an offshore island much like
Vancouver Island is today. Due to plate movement,
this island slowly moved south with the Juan de Fuca
Plate. Eventually it joined with Washington. As it
did, pressure pushed these mountains higher out of
the Pacific Ocean. The Olympic Mountains quickly
rose to an elevation of nearly 8,000 feet. The
beautiful Olympic Mountains are host to
one of our nation’s national parks.
Olympic National Park includes much of the
mountain range and ocean beaches along the Pacific
Ocean. The Olympics also receive more precipitation
than any area within the lower 48 states. This
abundance of moisture allows the Olympic
Mountains to host the only rain forest in North
America. Are you aware of any other rain forests in
the world?
The Hoh rain forest, in Washington, is filled
with moss-covered 1,000-year-old evergreen trees
that tower over 250 feet above the forest floor. In
contrast to the lush rain forest are the highest
elevations of the Olympic Mountains. These rugged
peaks are covered in low vegetation and snow much
of the year.
Okanogan Highlands
In northeastern Washington, just north of the
Columbia River, are the beautiful Okanogan
Highlands. The highlands combine with the San Poil
and Selkirk mountains to form a portion of the
western Rocky Mountains. The remote Okanogan
Highlands were once covered by large lobes of
continental glaciers. The glaciers eroded and carved
the deep river valleys. Sparse
vegetation and very limited pine forests cover most
of this region. However, the vegetation becomes far
more dense in the remote Blue Mountains.
Blue Mountains
The Blue Mountains are an offshoot of the
Rockies and are located in southeastern Washington.
These mountains were formed by the uplifting of the
Columbia Plateau. The Blue Mountains were a
physical obstacle for those who once traveled west
along the Oregon Trail. The high temperatures and
dry, rugged landscape made travel by wagon very
difficult. The higher elevations of the Blue
Mountains are one of the few forested regions in the
state’s interior. In contrast, the lower slopes of the
mountains are covered in grasses. Before we end our
focus on the mountainous areas of Washington, it is
good to take note of the diversity of our mountains.
There are many important differences from one
mountain region to the next. Moving down the slopes
of our mountains to the hills, we find that there is
great diversity here as well.
Hills
Hills are landforms between 500 and 2,000
feet of local relief. Do you remember our discussion
about local relief? Wherever mountains exist, the
lower slopes are called foothills. The Olympic,
Cascade, and Rocky mountains all have foothills.
Two of our most important hills are the Willapa and
Palouse. The Palouse Hills in southeastern
Washington are large, rolling hills. They were formed
by wind blown soil, called glacial till, during the ice
ages. These hills are now productive farmland. In
contrast, the Willapa Hills of southwestern
Washington were formed by plate tectonics. These
heavily forested hills produce much of the timber in
our state. The lower elevations of the Olympic
Mountains and Rockies are not nearly as
economically important to Washington as the western
and eastern foothills of the Cascade Mountains. The
Cascade foothills are important for their lumber,
minerals, grassland, and beauty.
Plateaus
Perhaps the most difficult physical landform
to recognize and define is the plateau. A plateau is
usually a tableland with an elevation of over 2,000
feet. A plateau will usually have a steep cliff on at
least one side. It is often surrounded by mountains
and deeply eroded by a river.
The Columbia Plateau covers much of
eastern Washington and Oregon, as well as southern
Idaho. The Columbia River eroded a deep valley
around the estern edge of the plateau. The steep
cliffs expose many layers of basalt to the forces of
wind and water. The surface of the Columbia Plateau
is also scarred. Glacial floods, dozens of times,
released massive amounts of water across the
tableland surface of the Columbia Plateau. These
scars are known as the Channeled Scablands. Other
features left by the glacial floods are falls, plunge
pools, and coulees.
Coastal Plains
The smallest landform in Washington is our
coastal plain. A plain is defined as any area with a
local relief of less than 500 feet. Much of our plain
lies near or along our Pacific coastline, so we refer to
it as a coastal plain. Our coastal plain is long and
very narrow. The coastal plain varies greatly from
one location to the next. The southern coastal areas
are gently sloping with wide sandy beaches. In
contrast, the northern coastline is rugged with steep
cliffs jutting from the ocean. Gravel, rocks, and
driftwood cover the narrow beach. This type of
coastline offers little protection from the pounding
surf.
Within our coastal plain are numerous
harbors and bays. Many have deep water. They
provide protection from the violent surf and ocean
storms. These two factors make our bays and harbors
excellent areas for seaports.
Our inland coastal lowlands are different
from the Pacific coastal plain. The coastal lowlands
are home to numerous bays, harbors, peninsulas, and
islands. Like our coastal harbors and bays, the
lowlands are also protected. They have deep natural
harbors. Some of these major inland waterways
include the Strait of Juan de Fuca, Hood Canal, and
Puget Sound.
The inland coastal lowlands are covered in
dense vegetation. The beaches are usually rocky with
an occasional sandy beach. The tides have a much
more prominent effect on the beaches of this region.
At low tide, marshes and tidal flats are exposed to
reveal their bounty of oysters, clams, and other sea
life. The inland coastal plain is protected from the
direct effect of Pacific storms. Occasionally this
region has a severe storm. Its pounding surf can
erode the land or beaches.
River Valleys
Ample rain and snow provide our abundant
fresh water. Water finds its way into our state’s
numerous rivers. Rivers and their valleys vary greatly
in length, flow, and source from east to west.
Western Washington river valleys are very
short, yet abundant. These rivers only travel a short
distance from the higher elevations of our mountains.
They flow directly into the ocean or one of our many
harbors, bays, or sounds. These rivers tend to flood
during the wet season.
Heavy rains in combination with warm
temperatures can cause these rivers to flood. The
warm temperatures melt the mountain snow. As the
water from the melting snow combines with the rain
water, these rivers flood. Floods are destructive to
personal property, but they are also an important
process of nature. The water, rich with minerals,
deposits new topsoil onto the floodplain. Some of
western Washington’s more prominent river valleys
are the Skagit, Cowlitz, Chehalis, and Snoqualmie.
All of these rivers are prone to flooding during the
winter months.
Eastern Washington has fewer river valleys,
but these rivers carry large volumes of water to the
Pacific Ocean. The two largest rivers in our state are
the Columbia and Snake. Both rivers have carved
deep and narrow valleys into the basalt of the
Columbia Plateau. These types of river valleys are
ideal for the construction of multipurpose dams.
Dams produce electricity, store water, and provide
the needed irrigation water for the farmland. The dry
farmland of eastern Washington needs irrigation
water to be productive. The water is pumped from
lakes, or reservoirs, behind the dams. The water is
then transported by canals to the farmland where it is
used to water the crops. Without these rivers and
their dams, water would not be available to irrigate
the crops. The dry, or arid, land could not produce
many of the crops grown today. Without irrigation
the desert would reclaim the land from the farmers.
Natural Environment
Washington has a very diverse natural
environment. Natural environment includes climate,
natural vegetation, and types of soil. Of all the
factors, the most important is geographic location.
Location affects every aspect of the natural
environment. The state of Washington is located
almost midway between the equator and the North
Pole. The state lies between the Columbia River
(46°N Latitude) to the south and the Canadian border
(49°N Latitude) to the north. The winds normally
blow from the west across the Pacific Ocean onto the
North American continent. Washington is located
east of the Pacific Ocean. The marine influence
affects both our temperature and amount of
precipitation.
Generally, landmasses in the middle latitudes
located near large water bodies have cooler summers
and milder winters. Marine air tends to cool summer
temperatures and warm thewinter temperatures. This
is possible because marine air tends to heat and cool
slowly. In contrast, air over a landmass tends to heat
and cool much faster. Therefore, the temperatures are
harsher in these interior regions. This is why the
western Washington temperatures are much more
constant during the year. Eastern Washington, in
contrast, has drastic temperature changes throughout
the year. This is because of the continental effect on
the climate.
Wind also has an effect on the natural
environment. The winds provide an abundance of
moisture to western Washington. In contrast, eastern
Washington is mostly dry and hot. The difference in
natural environments is primarily due to the
“rainshadow effect.”
The Cascade Mountains are a physical barrier
to the moist air blowing in from the Pacific Ocean.
This barrier traps a majority of the moist air on one
side, leaving the other side dry. This barrier and its
effects on the moisture is one of the most important
factors affecting our contrasting natural environment.
The rainshadow effect changes the climate,
vegetation, and even the soil.
Climate
Washington has three general types of
climate. These climatic types include west coast
marine, highland, and semiarid. The west coast
marine climate is found west of the Cascades below
3,000 feet in elevation. The highland climate occurs
where elevations are greater than 3,000 feet above
sea level. Finally, the semiarid climate is found east
of the Cascade Mountains and under 3,000 feet of
elevation.
West Coast Marine Climate
The west coast marine climate is located in
the lowlands of western Washington. This climate is
mild with plenty of moisture throughout the year.
Precipitation amounts range from 16 to 200 inches a
year. Most areas within this climatic region receive
30 to 60 inches. Much of the moisture falls from
October to May. Summer temperatures are mild,
normally ranging from 65 to 85 degrees.
Temperatures may occasionally reach the high 90s.
Winter temperatures are mild and range from 35 to
55 degrees. Temperatures below 32 degrees are rare,
and subzero readings are even more uncommon.
With the mild annual temperatures and abundance of
moisture, the west coast marine climate is ideal for
people to live and work. Most of Washington’s
population lives within this climatic region. In stark
contrast, the highland climate has the fewest people.
Highland Climate
The highland climate covers the higher
elevations of the Olympic, Cascade, and Rocky
mountains. The summers are short and cool. Winters
are long, cold, and wet. The highland climate
receives large amounts of precipitation from
September to June. Most of the precipitation that falls
during these months is in the form of either rain or
snow. The highest peaks in this region are capped
with glaciers and snow. Mount Baker holds the
world’s annual snowfall record. It received a total of
1,124 inches of snow between November 1, 1998 and
May 12, 1999.
Semiarid Climate
The semiarid climate is the third major
climatic type. A semiarid climate is defined as
regions of land that receive less than 20 inches of
precipitation a year. Precipitation falls in the form of
rain and snow during the winter months. Rain is
uncommon during the hot summer months. When it
does rain, it usually comes in the form of a
thunderstorm.
Long and cold winters are normal for much
of eastern Washington. Winter temperatures range
from below zero to freezing. In contrast, summer
temperatures range from 90 degrees or more.
Temperatures over 100 degrees are common in many
areas of the semiarid climate. The lack of moisture
and high heat during the summer months limits the
natural vegetation to grass and sagebrush. Trees grow
along streambeds and in the mountains.
Weather
Every community in Washington has
different weather conditions. Weather is the daily
conditions of temperature, barometric pressure, wind,
humidity, precipitation, and cloud cover. Each
community has a different variation of both weather
and climate. Weather represents short-term
conditions while climate considers a pattern of a
region over a longer period.
Temperature
Temperature is affected by many different
conditions. Latitude is an important factor in
influencing temperature. The further north from the
equator, the less direct sunlight received by the
higher latitudes. Location to large bodies of water is
another important factor influencing temperature.
The temperature of water changes very
slowly. This slow change in temperature affects the
air temperature near the water. Another major
influence on temperature is elevation. As we learned
earlier, elevation also has an affect on temperatures.
Generally, higher elevations have lower temperatures
than the areas below.
As you rise in elevation, the temperature
decreases three to four degrees for every 1,000 feet.
This change in temperature based on elevation is the
lapse rate. As we can see by the change in vegetation
of eastern Washington, mountains also affect
precipitation.
Precipitation
Washington usually receives most of its
annual precipitation from early October to April. The
driest period of the year is from July through
September. The heaviest precipitation occurs in
western Washington. However, along the western
slopes of the Olympic and the Cascade mountains,
the total annual rainfall and snowfall amounts are
very high. Precipitation amounts
are significantly less on the eastern slopes of the
mountains.
Vegetation
Eastern Washington’s lack of moisture limits
its vegetation to grasslands. Short, thin steppe grasses
and sagebrush cover the dry landscape. Ranchers
raise livestock, and farmers plow the land to raise
wheat, barley, and other dry land crops. Humans
frequently alter the naturallandscape by planting
many crops, shrubs, bushes, and trees.
In contrast, western Washington is covered in
dense conifer and deciduous forests. Conifer trees are
cone-shaped with a straight trunk, needles, and a
shallow root system. The most widespread and
valued conifers include Douglas fir, Sitka spruce,
pine, western hemlock, and western red cedar.
Conifers are a softwood tree. Softwood refers to the
ease in which the wood can be cut or worked. A
deciduous tree is a hardwood tree. Deciduous trees
have a circular shape, deep root system, broad leaves,
and short trunks.
Soils
The type of vegetation growing in an area is
largely determined by the soil. Washington has many
different types of soil. Erosion of the mountains
brings rich silt or topsoil to the lowlands and river
floodplains. Soils moved by water from one area to
another are called alluvial soils. These fertile soils are
deposited in our major river valleys of western
Washington. In contrast, the soils of eastern
Washington are primarily the result of wind. These
soils, likewise, are very productive. In the hot and dry
climate of eastern Washington, water quickly
evaporates. This leaves minerals at the surface. This
is one reason why the soil is productive when water
is added. However, where too much moisture is
received, the soil is infertile. Infertile soils are created
when water carries the minerals deep into the soil.
These are leached soils. This prevents plants from
reaching the minerals to help them grow.
Summary
Washington’s natural environment offers a
moderate climate, lush vegetation, and fertile soils.
Washington rarely has natural disasters caused by
hurricanes, cyclones, typhoons, tornadoes, or
blizzards. However, we do have windstorms,
flooding, and drought. Fortunately, these climatic
events are usually not life threatening. Our climate
makes life enjoyable for the people who live, work,
and visit our beautiful state.