CHAPTER SUMMARY: The Klamath Basin sits on the border be-

tween two major geologic areas. Volcanoes rise on one side of the Ba-

sin. Broken pieces of the earth’s crust are on the other side. This land-

scape has made the Klamath Basin a beautiful place to live. Our moun-

tains provide both challenges and opportunities for the people who

live here. Geology also has a big influence on weather in the Klamath

Basin.

The Klamath Story

Chapter 1

Geologic Forces Shape Our Landscape

Stukel Mountain rises more than 2,000 feet above the floor of the Klamath Basin. Both Stukel and nearby Hogback Mountain

were created by “faults” in the earth’s crust. Other mountains in our area are volcanoes.

Vocabulary list

� Geology

� Stratovolcano

� Shield volcano

� Basin and range

� Rain shadow

� Geothermal

MOUNTAINS RISE

K lamath Falls and most of the smaller towns in

our area are located in the Klamath River Ba-

sin.* The word “basin” refers to the large area of

land in Southern Oregon and Northern California

where all streams flow into the Klamath River.

The Klamath Basin has many hills and moun-

tains that were shaped over a very long time. The

study of how hills, mountains, valleys and canyons

were formed is called geology.

Some of the biggest mountains in our region are

volcanoes. There are two types of volcanoes found in

our area.

spear points and knives.

Most of the big volcanoes in our area are on the

west side of the Klamath Basin. They are part of the

Cascade Mountain Range.

BASIN AND RANGE

Many mountains in our area were formed a dif-

Stratovolcanoes form

high peaks with eruptions of

lava, ash or gas at or near the

top. Mount Shasta is the largest

example of a stratovolcano in

our area. Mount Shasta has

been quiet for many years, but

geologists believe it is likely to

erupt again someday.

Mount McLoughlin is an-

other example of a stratovolca-

no. It has been quiet for a long

time, and is not expected to

erupt ever again. Crater Lake

was formed following the col-

lapse of a large stratovolcano

around 7,700 years ago.

Shield volcanoes also produce lava, but do

not build up high peaks. Instead, the lava flows

across the ground in repeated eruptions, layer upon

layer. Massive mounds of lava form a more rounded

mountain on the earth’s surface.

The largest shield volcano in our area is the

Medicine Lake Volcano, located about 45 miles

south of Klamath Falls. Geologists believe the

Medicine Lake Volcano has been producing lava

flows for a half-million years or more.

There’s one place where eruptions of lava from

the Medicine Lake Volcano occurred fairly recently

– as little as 1,100 years ago. That may seem like a

long time ago to us. But in the life of a volcano,

1,100 years is not long at all. The place where these

recent eruptions occurred is in the Lava Beds Na-

tional Monument. Many people come from far away

to visit the Lava Beds. People like to explore some

of the caves that were formed by flowing lava at the

Lava Beds.

The Medicine Lake shield volcano has also

produced massive amounts of obsidian, a volcanic

glass that often has very sharp edges. Obsidian was

extremely valuable to Native Americans, because

they could use the sharp rocks to make arrowheads,

Mount Shasta is one of the largest stratovolcanoes in the Cascade Mountain Range. It is about 60 miles south of Klamath Falls. This photo was taken around 1930.

Major mountains

in the Klamath region

� Mount Harriman, elevation 7,979 feet.

� Gearhart Mountain, 8,135 feet.

� Pelican Butte, 8,036 feet.

� Hogback Mountain, 6,200 feet.

� Stukel Mountain, 6,525 feet.

� Yainax Butte, 7,222 feet.

� Walker Mountain, 7,083 feet.

� Diamond Peak, 8,744 feet.

� Mount McLoughlin, 9,495 feet.

� Mounta Shasta, 14,162 feet.

range province.”

There are many interesting types of rocks found

in our area. By far the most common rock in the re-

gion is basalt. Along with obsidian, other interesting

rocks in the region include opals, feldspar, pumice,

diatomite and petrified wood.

HOW’S THE WEATHER?

The many mountains we have in our area make

the Klamath Basin a beautiful place to live. Our

mountains provide lots of places to go camping,

hunting, fishing and hiking. Many people come

from other parts of the country to see our moun-

tains.

In some ways, however, our mountains make

life harder. For example, the mountains to the west

of Klamath Falls cause storms to drop most of their

moisture before reaching our area. Klamath Falls is

ferent way – when huge pieces of the earth’s surface

broke apart. Some parts of the ground rose high up in

the air, and other sank lower.

The place where a piece of earth rises is called a

mountain “range.” Hogback Mountain, just east of

Klamath Falls, is an example of a mountain formed

in this way. Other examples include Stukel Mountain

near Henley, and Modoc Rim near Chiloquin.

The place where a piece of the Earth sinks lower

is called a “basin.” In this case, the use of the word

“basin” means something slightly different. Here the

word “basin” refers to a broad flat valley located

next to a “range.” The city of Klamath Falls sits in a

basin.

This broken pattern of the Earth’s surface is

seen in many places to the east of Klamath Falls.

From an airplane, you can see range after range.

There’s always a basin sitting between each set of

ranges. Geologists call this region the “basin and

Crater Lake is not only Klamath County’s most famous tourist attraction, but is also the deepest lake in America. It was

formed by the eruption and collapse of a volcano about 7,700 years ago.

CHAPTER 1 REVIEW

1. Which type of volcano do you think is more interesting, stratovolca-

noes or shield volcanoes?

2. How many mountains in our area can you name?

3. We know Klamath Falls doesn’t get much rain in most years. How

does that affect the type of plants that can grow here?

4. Think about it: Some people don’t like the cold winters we have

in the Klamath Basin. But many people are glad it never gets too hot. How

do you like the weather here?

5. Decision: It doesn’t rain very often in the Klamath Basin. We

enjoy lots of sunshine, but it’s usually very dry and the barren hills turn

brown in summer. If you had the chance, would you move someplace

where it rains more often?

situated in what’s called a “rain shadow,” meaning

we get very little of the moisture that comes off the

Pacific Ocean. As a result, we have a relatively dry

climate that makes it harder to grow crops.

Furthermore, the Klamath Basin sits at a high

elevation of about 4,100 feet above sea level. Be-

cause of this, we have cooler temperatures and a

shorter growing season than other parts of Oregon.

That makes it harder for farmers to grow crops. If

you pay attention to weather reports, you’ll notice

it’s usually about 10 degrees warmer in Medford

than it is in Klamath Falls. That’s because Medford

is at a much lower elevation, where the air stays

warmer. That means we have colder winters in the

Klamath Basin. But it also means it doesn’t get so

hot in the summer.

There’s one other thing about the geology of

our area that is important. We are lucky to have

many places where hot water is found just below

the surface of the earth. Water that comes out of the

ground hot is called geothermal water. In some

places the geothermal water comes out of the

ground at nearly 200 degrees Fahrenheit – close to

boiling! This hot water is used to heat businesses,

homes and schools. IFA Nurseries in Klamath Falls

uses geothermal energy to heat greenhouses where

millions of tree seedlings are grown every year.

As we travel around the Klamath Basin, it’s

interesting to think about how long it took for our

mountains and lakes to form, and how different life

would be for us if the ground in this area were

simply flat.

* The communities of Gilchrist and Crescent in northern

Klamath County are located in the Deschutes River Basin,

which flows into the Columbia River.