Chapter 3



Chapter 3 -West Versus East

The Cascade Mountains divide Washington into two very different environments. A mild, moist climate and dense forests dominate the region west of the mountains. To the east, however, the climate is dry and hot. There is little vegetation other than sparse trees, sagebrush, and grasses. Because of the Cascade Mountains, Washington has two environments as different as night and day.

As you might have guessed, western

Washington includes all areas west of the Cascade Mountains. Frequent rains and mountain snowfall provide this region with an abundance of water. The rain and melted snow flow from the mountains into western Washington’s many lakes and rivers. This moisture allows many types of trees and plants to thrive in this mild, moist climate. Thus, our

state is nicknamed, “The Evergreen State.”

NW NE

SW SE

In contrast, the climate in eastern Washington is much more harsh and dry. Only scattered trees and vast areas of sagebrush and grass thrive here. These types of vegetation do not

require regular moisture. Of course irrigation has made it possible for other plants and crops to grow in eastern Washington. Physical formations of granite and basalt also dominate the region.

These features and climate have combined to create a hostile environment. To develop a better understanding of each region, we will discuss the physical features, climate, and vegetation of each in more detail.

Western Washington

Western Washington includes all areas west

of the Cascade Mountain crest to the Pacific Ocean.

Physical Features

A great variety of physical features exist in

western Washington. Our shoreline is irregular with numerous harbors and bays. Willapa Bay, Grays Harbor, Hood Canal, and Puget Sound are some of the more well-known.

In addition to the many harbors and bays,

western Washington has numerous lakes and rivers. The lakes in this region are fed year round by high levels of precipitation and melting snow. Rivers and streams also receive much of their water in this fashion.

Rivers in western Washington can flood during times of heavy rains and warmer winter temperatures. Flooding usually happens during the rainy season. Floods often destroy property and harm communities. Although often dangerous, floods play an important role in the renourishment of floodplains.

Mountains are easily-spotted physical

features in western Washington. The major uplands include the Willapa Hills, the Olympic Mountains, and the Cascade range and its major volcanoes. Some volcanic peaks can rise more than 6,000 feet higher than the highest peaks of the Cascade Mountains.

When the ice from the last ice age began to

melt, the ocean rose and flooded western Washington. The flood covered the lowlands.

This left many peninsulas and islands. The two largest peninsulas in western Washington are the Olympic and Kitsap peninsulas. Islands also dot the waterways of western Washington. The San Juans, Bainbridge, Vashon, and Whidbey are some of the many popular islands in this region.

Climate

There are two climates within the western

Washington region. They are the west coast marine and the highland climates. The dominant climate of the lowlands is west coast marine.

This climate has frequent rainfall throughout most of the year. Rainfall usually declines during the summer. Summer temperatures are mild with limited humidity. Winter temperatures remain unusually mild given our northern latitude. This is because of our location next to the Pacific Ocean. The ocean affects our climate by keeping the temperature more constant.

In contrast, the mountains of western

Washington have a highland climate. These areas

of western Washington have short, cool, and rainy summers. The winters are long, cold, and receive much more snowfall than the lowlands.

The moderate temperatures and abundant moisture in western Washington support dense vegetation. Evergreen forests and deciduous trees cover the landscape like a thick, green carpet. The highest mountain peaks have little or no vegetation growing on their slopes. In contrast, the lowlands have roads, farms, and cities carved from the orest. As the region has grown, people have removed more of our forests.

Vegetation

A mild and wet climate allows dense stands of vegetation to grow in western Washington. The thick canopy of evergreen trees provides shade for the plants on the forest floor. Hemlock, cedar, spruce, alder, and maple trees provide habitats for animals and other plants in our forests. Without a doubt, the vegetation in western Washington is very unique!

The abundant moisture and the shade of the canopy allow only certain types of plants to grow. Rhododendrons, azaleas, ferns, and mosses all grow well in this climate. Mushrooms also thrive in the shaded environment. Some of the finest mushrooms in the world grow on our forest floors. Before you ever pick or eat a mushroom, make sure it is not poisonous.

Other areas of the forest have been cleared

by logging or fire. Alder, ash, and maple trees grow well in the forest clearings. River valleys where sunlight is common also make good homes for these trees. The river valleys and flood plains are great locations for farms. Farmers can grow everything from flower bulbs to cranberries.

Subregions

Western Washington may be divided into three subregions. Each subregion has its own unique physical features, climate, and vegetation.

How do these regions differ from one another?

Coastal Subregion

The coastal subregion is a beautiful area of

Washington. Mountains, bays, peninsulas, and even a rain forest are found here. This area has a very moderate climate with dense vegetation. People live in small communities and depend on

the natural resources of this region.

Physical Features

Coastal mountains rise throughout the long, narrow coastal subregion. The Olympics are this region’s most notable mountains. These rugged mountains rise nearly 8,000 feet above the Pacific.

Glaciers can be found on the higher peaks. The mountainous terrain is also home to many alpine lakes. The rugged terrain makes these small lakes difficult to access.

Precipitation and melting snow provide water for many short rivers. They flow into the Pacific and its many bays and harbors. Willapa Bay and Grays Harbor are just two of the largest in the subregion. The largest river in Washington, the Columbia, forms the southern boundary of the coastal subregion.

Climate

The coastal subregion has only two climates. These climates are the west coast marine and the highland climates. The higher elevations in the Olympic Mountains have a highland climate.

Rain and snow fall much of the year. In some of the higher, shaded elevations, glaciers slowly move down the steep mountain slopes.

The lower elevations of the coastal subregion are subjected to the west coast marine climate.The abundant moisture and mild temperatures are perfect for the dense vegetation that grows here. In fact, the only temperate rain forest in the lower 48 states is located here! The Hoh rain forest is a beautiful place to visit. There you can see trees more than 500 years old.

Vegetation

Dense stands of trees cover much of this

coastal subregion. Hemlock, cedar, and spruce provide a thick evergreen canopy. This canopy allows little sunlight to reach the forest floor. Moss, ferns, nettles, lupines, lichens, rhododendrons, and thousands of other plants thrive in the shaded areas.

Giant trees such as Sitka spruce, hemlock,

and western red cedar have fallen and crisscross

the forest floor. These fallen giants allow light to bathe the forest floor where they once stood. The light and nutrients from the decomposing wood allow a variety of new plants to thrive in the vacant area. The seedlings of the cedar and spruce grow quickly reaching for the light with the hope that someday they will be a giant.

However, people have invaded this pristine

region of our state to harvest the timber from the

forest. Loggers clear-cut giant cedar and spruce trees and left only the hemlocks. Hemlocks thrive

in the shade of the forest. Exposed to the sunlight,

seedlings grow quickly. The hemlocks remain as

proud reminders of the original forest that thrived in this region for centuries.

New plants and vegetation eventually replaced the natural forest. Alder trees, which once lived only along the beaches, spread inland. Raspberries and blackberries, in a bath of light,

spread in every direction. Eventually the loggers realized that the hemlock was valuable not for its wood, but instead for its sap. The large giants’ sap provides rayon for plastics. Hemlocks, the last trees remaining, were cut as fast as the other trees in our forest.

Fortunately the hemlock, spruce, and cedar

can thrive in the protected areas of our national

parks and wilderness areas. Hopefully, plant

and animal habitats will be restored as they were

just 100 years ago.

Western Lowlands Subregion

The western lowlands subregion is clearly

one of the most beautiful and diverse regions in our state. The lowlands have numerous hills, streams, rivers, lakes, and much more to offer.

The weather is mild in both the summer and

winter months. Moisture keeps the trees, grasses,

and other plants green year-round.

Physical Features

The western lowlands is a complex area due to the erosion from glaciers and water. Its most

important physical feature is Puget Sound. This waterway extends south from Everett to Olympia. Puget Sound, Hood Canal, and the Strait of Juan de Fuca form the major inland waterways of western Washington.

Long ago, as the glaciers melted and retreated north, rising sea level flooded the interior

lowlands of western Washington. The water covered all the land except only the highest portions of the hills and mountains. These

uncovered pieces of land became the islands and

peninsulas in western Washington.

The Olympic and Kitsap peninsulas, and

Whidbey, Bainbridge, Vashon, Mercer and the

San Juan islands are important physical features

in the western lowlands. The protected waterways provide excellent ports and shipping lanes. Ocean-going vessels can travel into the lowland region and safely off-load their cargo.

Rivers and streams also flow from the nearby Cascade and Olympics mountains into the

lowlands. From the Columbia in the south to the

Nooksack north of Bellingham, there are hundreds of rivers in this region. These rivers are fed by heavy rainfall and melted snow. They frequently flood and deposit their fertile silt on the floodplains.

Climate

The western lowlands has only one type of

climate, the west coast marine. This subregion receives plenty of rainfall and an occasional snowfall each year. Most areas receive 40 to 60

inches of precipitation each year.

The Pacific Ocean maintains the mild temperatures. They tend to be mild throughout the year. Summers are very comfortable because of the mild temperatures and infrequent rain. Temperatures occasionally reach the upper 80s and low 90s, but normally they range from 65 to

85 degrees.

Winter weather is also mild but very wet.

The lowlands receive most of its rain in the winter months and early spring. Temperatures are comfortable because of the influence of the Pacific. Winter temperatures are rarely extreme, or below zero, for long periods. An occasional storm, blowing in from the north Pacific, may bring snow and subfreezing temperatures to the lowlands. When these storms hit, they rarely last more than three to five days.

Vegetation

The natural vegetation in the western lowlands is mainly made up of conifer and deciduous forests. These thick forests are different from those of the coast. The conifers in this region, in contrast, are smaller than their cousins in the Olympics. Douglas fir, western red cedar, western hemlock, and Sitka spruce all grow in the western lowlands subregion.

Deciduous trees also grow well in the mild and wet climate. Alder, maple, and oak trees line the banks of the rivers and grow around the flood plains. Other plants and shrubs grow quite well in the forest. Rhododendrons, lupine, azaleas, ferns, and berries are common in the lowlands. However, human activity has greatly changed the natural vegetation. People have cleared the forests for roads, communities, and factories. Domesticated plants and trees have replaced some of the original vegetation of the lowlands.

Western Cascades Subregion

The Cascade subregion of western Washington is located west of the Cascade Mountain crest. This region includes the western

slopes, or windward side, of the Cascades from

Canada to the Columbia River.

Physical Features

The most obvious feature of the western

Cascades subregion is the Cascade Mountains.

The Cascades extend more than 600 miles from

British Columbia, Canada to northern California.

Glaciers and deep snow dominate the rugged north Cascades. Mount Baker is the only major volcanic peak in this area. However, the North Cascades have hundreds of jagged granite spires jutting skyward.

As you travel south through the subregion,

the mountains become less dominant in height but are still very beautiful. Volcanic peaks now dominate the mountain skyline. Two major volcanoes, Mount Rainier and Mount St. Helens,

are in this region. Mt. Rainier, the tallest peak, is

14,411 feet tall. It stands more than 6,000 feet

higher than any of the surrounding mountains.

The subregion is also home to many alpine lakes, streams, and rivers. The water flowing into them once fell as either rain or snow. The melting snow and running rain water collect in the valleys and continues its journey to the ocean.

Climate

The western slope of the Cascade Mountains has a highland climate above 3,000 feet. The lower elevation has a west coast marine climate. The highland climate can change very quickly. As storms push in from the Pacific, thick clouds

form and release heavy rain or snow.

The windward location of the western

Cascade subregion causes heavy precipitation.

The heaviest precipitation, both rainfall and

snowfall, occurs from early October to late April.

Annual snow pack can be as much as 30 to 90 feet

in places.

Vegetation

Evergreen forests blanket the western slopes of the western Cascade subregion. The higher elevations are usually void of trees. Only shrubs, low lying plants, and mosses can survive the cooler temperatures and heavy snows. The

warmth of late spring and early summer brings a variety of alpine flowers and grasses into bloom.

The area above where trees can grow is known as the tree line. You can see the natural tree line on many of the higher peaks in the Cascades.

Eastern Washington

Eastern Washington is the second major

geographical region in our state. This large region

includes all the land east of the Cascade Mountain

crest to the Idaho and Oregon borders. The region of eastern Washington is very different from the western Washington region.

Eastern Washington has less precipitation,

extreme temperatures, and very few trees. Grasses and sagebrush cover much of the area. The drier climate is a direct result of the rainshadow effect. Please review page 29 if you would like to learn more about this climatic feature.

Physical Features

Many unique physical features are found

within the eastern Washington region. These features include the eastern Cascades, the Okanogan Highlands, the Rockies, and the Blue

Mountains. The rolling hills of the Palouse and the Columbia Plateau are other impressive landforms. Fire and ice helped to form these physical features.

Although the climate is very dry throughout the year, the region has several major rivers and lakes. Lake Chelan, Moses Lake, the Potholes, and Franklin D. Roosevelt Lake are large and popular freshwater lakes. There are also many alpine and glacial lakes in the mountain areas.

Two volcanic peaks dominate the eastern

Cascade Mountains. One, Glacier Peak, is rarely

seen unless you are at a high vantage point. It towers above the North Cascades in eastern Washington. Mount Adams in southern Washington is the last of the major volcanic peaks in our state.

The winter snow melt of the Cascade, Rocky,and Blue mountains fills the many rivers in the region. The Columbia River is the main river that flows through eastern Washington. The

Columbia starts its journey to the Pacific Ocean in British Columbia, Canada. Every other major river in eastern Washington is a tributary of the Columbia. A tributary is a river that flows into a larger river before reaching the ocean. The tributaries also carve the region’s numerous river valleys.

Climate

The eastern Washington region has only twomajor types of climate; semiarid and highland.

The region does not receive much precipitation.

The Cascades prevent the moisture from reaching

the region. The surrounding mountains severely reduce the amount of moisture the region receives. The eastern slope of the Cascades receives no more than 15 to 30 inches of moisture each year. It continues to decline the farther east you travel until you reach the foothills of the Rocky Mountains.

The Columbia Plateau receives less than 15

inches of precipitation a year. Areas which receive

less than 15 inches of precipitation are classified

as semiarid climates. This climate receives most of their moisture during the winter months. Semiarid climates receive a little more rainfall than a desert.

Winters are long and frequently very cold. Summer temperatures, in contrast, are quite hot and dry with daytime highs reaching 90 to 100 degrees in July and August. Similar to deserts around the world, nighttime temperatures drop 30 to 40 degrees from the daytime high.

The highland climate is found in the higher

mountain elevations. The highland climate has a

very short, cool summer. Summer temperatures

are mild with very little moisture. In contrast, winters are long and very cold. Daily high temperatures rarely reach zero. These cold temperatures bring plenty of snow. The first snow usually falls as the leaves begin to change color in the higher elevations. Snow remains throughout the winter. Melting of the snow begins as spring approaches.

Vegetation

The dry climate allows only certain types of

hardy plants to grow. The semiarid areas have different types of vegetation than the mountains.

The mountains have widely spaced trees. The common types are pine and fir. The higher summer temperatures and lack of moisture force the evergreens to grow farther apart. They do this to insure that each tree receives enough moisture to survive. Ponderosa pine, Douglas fir, and western larch are the evergreen trees of eastern Washington. Spread among the evergreen trees are numerous types of grasses and other vegetation. The plants that grow in this climate need to be drought resistant. Traveling down the slopes of the mountains, moisture decreases.

The trees give way to only grasses and sagebrush. There is not enough moisture to allow trees to survive, except next to rivers and streams. Trees that grow well in these areas are alder, maple, ash, oak, and elm. These trees are very common along our streambeds and major rivers. Heading away from the rivers into the dry and harsh Columbia Basin, only sagebrush and grasses grow.

Subregions

The eastern Washington region includes five subregions. They are the eastern Cascades, the Columbia Basin, the Okanogan Highlands,

Palouse Hills, and Blue Mountains. These

subregions are both unique and very different

from one another.

Eastern Cascades Subregions

The eastern Cascades subregion includes all areas east of the crest of the Cascade Mountains to the Columbia River. This area also includes the North Cascades and continues east to the Okanogan River. It is a beautiful and diverse.

Physical Features

Lying within the eastern Cascades subregion is a very mountainous region. Tall granite spires jut from the Cascades, such as Mount Stuart and the Enchantments. Mount Stuart, at an elevation of 9,470 feet, is one of the highest

non-volcanic peaks in Washington. Southern mountain peaks are quite different from their northern cousins in this subregion. The mountains change from the jagged granite peaks in the north to rounded basalt mountains and towering volcanic peaks to the south.

Mount Adams, a volcanic peak, is the highest mountain in this region. It stands at an elevation of 12,307 feet. Mount Adams is a unique volcano. It is composed of at least three volcanic cones that have merged. Another volcano in this

subregion, and often the least known, is Glacier

Peak. At an elevation of 10,436 feet, this peak is well hidden by the surrounding peaks of the Cascade Mountains.

Several rivers flow east from the Cascade

crest to join the Columbia River along its southern

journey. These fast-flowing cold rivers have eroded deep valleys along the mountain slopes. The Yakima, Kittitas, and Wenatchee valleys are

the largest in the region.

Climate

The rainshadow effect influences the climate east of the Cascades. Precipitation amounts decline rapidly from the crest of the Cascades toward the Columbia River. Moisture continues to decline even more heading into the semiarid Columbia Plateau. Total precipitation drops from 100 inches at the crest to six to eight inches near the Columbia River. Much of the precipitation falls in the form of snow during the long, cold winters.

Vegetation

The Cascade crest is not only the top of the

Cascades, but it is the point where the vegetation

changes on either side of the crest. Heading east,

the dense forests give way to the Douglas fir and

a variety of pines. Both types of trees do well in the drier climate to the east. The once dense undergrowth of vegetation near the crest quickly

changes to mostly sagebrush and grasses.

The northern areas of the eastern Cascades

subregion remain forested with stands of western

larch and Douglas and silver fir. Heading farther

east from the crest, the vegetation continues to

change as trees become fewer and fewer. Finally,

the only trees remaining are the ones growing

along the banks of rivers. Grasses and sagebrush

have replaced the stands of Douglas fir and

ponderosa pine.

Columbia Basin Subregion

The Columbia Basin subregion is the driest

area of our state. Scarce fresh water and a lack of

protection from the heat makes it difficult for

vegetation to grow. The Columbia Basin occupies

a small portion of the entire Columbia Plateau.

This region extends east from the Columbia

River to the subregion of the Palouse Hills. It

continues north to the Columbia River and the

Okanogan Highlands. This is a very harsh

environment.

Physical Features

The land in this subregion is mainly flat.

Ravines and channels cut into the terrain. The

Columbia, Snake, and Spokane rivers flow along

the edges of the region. These three rivers have

cut deep valleys into the basalt forming a plateau.

Plateaus are the only major physical feature of the Columbia Basin subregion. Included are the Waterville and Columbia plateaus. The Columbia Basin and the Channeled Scablands have been severely eroded by water and wind.

Glacial floods cut deep scars called coulees into the layers of basalt. The coulees may be hundreds of feet lower than the surrounding basalt cliffs.

Climate

The climate of the Columbia Basin subregion is semiarid. The amount of precipitation varies from five inches to no more than 25 inches near the foothills of the Rockies. It can get very hot

and dry during the summer. Winter, in contrast,

is very cold and often has drifting snow.

Vegetation

Sagebrush is common and trees are rare,

except along the occasional river bank. Steppe

grasses and sagebrush cover the landscape as far

as the eye can see. Only when the landscape reaches the foothills of the Rockies are there trees. Trees and a variety of plants thrive because of the increased moisture falling on the foothills.

Okanogan Highlands Region

The Okanogan Highlands form the northernmost subregion in eastern Washington. This area extends east of the Cascades across the

northeastern portion of the state. The Columbia

and Spokane rivers form the southern boundary

of this subregion.

Physical Features

The terrain of the Okanogan Highlands

subregion is very rugged and mountainous. It

includes the Okanogan Highlands, San Poil and

Selkirk mountains, and a small portion of the

Rockies. These mountains are some of the youngest granite features in our state. One of

these, the Golden Horn Batholith, includes

several peaks over 8,500 feet.

The Columbia River divides this subregion

into two parts. The western portion includes the

Methow, Okanogan, and San Poil rivers. The

eastern portion includes the Pend Oreille, Colville, and Spokane rivers. These rivers cut deep valleys into the mountains and provide a large portion of the water for the Columbia.

Climate

The Okanogan Highland subregion has very

cold winters and warm summers. The higher

elevations have a highland climate, and lower

elevations are semiarid. Snow falls frequently during the cold and windy winters. Summers

are warm with little precipitation after May and

June. An occasional thunderstorm might rumble

through the region in mid-summer. These storms

bring the threat of lightning and wild fires. Forest fires are common in the mountains of our state. The most severe fire season in recent years occurred in the summer of 1994. Tens of thousands of acres of forest were burned.

Vegetation

The Okanogan Highlands subregion is

forested with a variety of evergreen and deciduous trees. The undergrowth consists of brush and grasses among the open trees. Fall is a beautiful time in the region. The steep slopes of the river valleys are covered with western larch, alder, ash, and maple trees. They turn brilliant colors as the autumn frost arrives.

Palouse Hills Region

The Palouse Hills and Blue Mountains form

another subregion in southeastern Washington. The Palouse Hills extend south from the Spokane

River to the Blue Mountains. The Blue Mountains

extend from northeastern Oregon into the extreme southeast corner of Washington.

Physical Features

The rugged Blue Mountains and the dune

shaped Palouse Hills are the major physical features in this subregion. Oregon Butte, the

highest peak in the Blue Mountains of Washington, rises 6,401 feet. The mountains of this region are believed to be one source of the basalt floods. The dikes and fissures here flooded the plateau millions of years ago.

The largest river of the region, the Snake,

divides the Palouse Hills from the Blue Mountains. The Touchet, Walla Walla, Grand Rhonde, and Tucannon rivers also cut deep gorges through this subregion on their way into the Snake or Columbia rivers.

Climate

Much of this Palouse Hills subregion has a

modified semiarid climate. It is considered to be

modified because the area receives more precipitation than other areas of eastern

Washington. The higher elevations of the Blue

Mountains have a highland climate. Snow falls in

this region during most of the winter. Winter tends to be very cold and windy. Summer, in contrast, tends to be very hot and dry with little or no moisture after April.

Vegetation

Steppe grasses and sagebrush cover most of the subregion. The grasses continue into the

higher elevations along with ponderosa pine and fir trees. The trees only grow on the moist upper slopes of the Blue Mountains.

Chapter Summary

The Cascade Mountains separate

Washington into two very different regions. The

climates are as different as black and white.

Within each region are many different subregions

with their own unique climates and vegetation.

The physical features of western and eastern

Washington are also extremely varied. It seems

that the only similarity is that the Columbia

Revegetation and dense forests dominate the west.

In the east, vegetation and trees are few and far

between. Mountains, hills, and plateaus dominate our landscape.

With such contrasting features, it is

sometimes hard to believe that eastern and

western Washington are part of the same

beautiful state!

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