Science High School Reviewer | Grade 4 Science | Earth Science | Shaping Earth | Lesson 16: Earth

Earth’s Landforms

Viewed from space, Earth’s land might seem
flat. From close up, you can see many natural
features on Earth’s surface. These features are
called landforms.

Tallest and Flattest
The tallest and most visible landforms are
mountains. Most rise steeply to a peak at the
top. Others have a gentle slope. Some are
volcanoes formed by melted rock.
A plain is the flattest kind of landform. Plains
are vast areas of land without hills or mountains.
Landforms Shaped by Water
Flowing water can shape the land. Streams
and rivers can cut small channels or larger
gullies where they flow. Strong flows can create
deep valleys. In some places, rivers form narrow,
V-shaped valleys called canyons. The Grand
Canyon is more than one kilometer deep!
Waves wear away land, too. Waves can make
a beach flat and smooth or sharp and rocky.
Landforms Shaped by Wind
Gusts of wind can pile sand into
large mounds in deserts and on
beaches. These mounds are called
sand dunes. Wind can also
combine with water to make
mountains steeper and
valleys deeper.

What does it look like
where water meets land?
Water always flows downhill.
What happens when it gets to the
bottom of a landform?
River Deltas
As the land gets flatter, the flow
of a river slows. If the river empties
into an ocean, the water moves even
slower. It drops off bits of sand and
soil it carried. The bits form a delta—
a landform shaped like a triangle.
Drainage Basins
Some rivers empty into channels.
A channel that carries water is called
a drainage (DRAY-nihj). A drainage
basin is the area of land drained by
flowing water. Much of central North
America, for example, is a drainage
basin for the Mississippi River.
Continental Shelves
It’s a sunny day at the beach. You
want to swim with your friends.
You move farther and farther from
shore, but the water is still too
shallow. Where are you? You are on
a continental shelf. The continental
shelf is the land connecting shore to
sea. It can stretch seaward for miles.

Beyond the Continent
Beyond the continental shelf is an
area of land called the continental
slope. This land is the steeper part
of the continent that slopes down
toward the ocean floor. Underwater
canyons can form on the slope.
At the base of the slope lies the
continental rise. The rise connects
the continent and ocean floor.
Most of the ocean floor is
flat and without features. Long
mountain ranges, though, stretch
through the middles of some oceans.
These are ocean ridges. The ocean
floor is spotted with undersea
volcanoes, too. Deep trenches can
cut far into the ocean floor.

What is below Earth’s surface?
You have read about some of the features on Earth’s
surface. What is Earth like beneath those features?
Look at the diagram. It shows the interior of Earth.
Scientists divide Earth into four main layers. (diagram)

Crust Solid rock that
makes up Earth’s
outermost layer. It is
brittle and can crack
easily. Earth’s landforms
and underwater features
are found on the crust.

Mantle Layer of rock
below the crust. It is
solid, but some of the
rock can move or
change shape at high
pressures and
temperatures.

Outer Core Liquid
layer below the
mantle. It is made
mostly of melted iron.

Inner Core Sphere of
solid material at Earth’s
center. It is the hottest
part of Earth. It is
probably made of iron.