Plate Boundaries and Land Formations

Lesson 2.2

L A N D F O R M S A T P L A T E

B O U N D A R I E S

Forces Changing Earth's Surface

Types of Forces

01
The squeezing force at a convergent boundary
Compression

The side-by-side dragging force at transform

boundaries

Shear

02

03

The pulling force at a divergent boundary
Tension

Mountain ranges are produced by plate tectonics. Tectonic plate move slowly, only 1-9 cm per year. But these
massive, slow moving plates have so much force they can build tall mountains

Compression, tension, and shear cause rocks to

change shapes in different ways.

Multiple Choice

A volcanic island arc forms when an oceanic plate is subducted.

• TRUE

• FALSE

Landforms Created by Compression

Ocean Trenches

Volcanic Arcs

When two plates collide, one can go under the other and be

forced into the mantle in a process called subduction.Ocean

trenches are deep, underwater troughs created by an oceanic

plate subducting under another plate at a convergent plate

boundary.

Volcanic mountains can form in the ocean where oceanic

plates converge and one plate subducts under another one.

These volcanoes can emerge as islands. A curved line of

volcanoes that forms parallel to a plate boundary is called

a volcanic arc.

The largest landforms on Earth are produced by

compression at convergent plate boundaries. The

types of landforms that form depend on

whether the plates are oceanic or continental.

Mountain Ranges

A collision between two continental plates can produce tall

mountains, but the mountains form slowlv and in stages over

millions of sears.

https://youtu.be/GyMLlLxbfa4

Seafloor Spreading

Multiple Choice

A mid-ocean ridge forms when tension acts on seafloor rocks.

• True

• False

The plates beneath India and as a started
colliding almost 50 mision years ago and
continue co ding today, Because the plates
are still collidina, the Himalavas grow a few
millimeters each year due to compression

also can form on continents. Mount
Shasta in California is part of the Cascade
volcanic arc. Note the ocean trench where
the plates meet.

Examples

Ocean trenches, also called deep-sea
trenches, are the deepest places in Earth's
oceans. The Mariana Trench, in the
western Pacific Ocean, is about 11,000 m
deep.

Landforms Created by Compression

Volcanic Arcs

Ocean Trenches

Mountain Ranges

Multiple Choice

Transform faults form when compression acts on rocks

• True

• False

Landforms
Created by
Tension

Mid-ocean ridges play an

important role in the

formation of ocean basins

Mid-ocean ridge

Continental Rifts

Ocean Basins

Multiple Choice

High mountain ranges can form on land where two plates diverge.

• True

• FALSE

Multiple Choice

A fault is formed by the movement of a __________ plate boundary

• Transform

• Convergent

• Divergent

Landforms Created by Shear

Transform Faults

Faults zone

Where blocks of crust slide horizontally past each other,

they form transform faults. Most transform faults form

perpendicular to mid-ocean ridges. Transform faults form

and can separate sections of mid-ocean ridges.

Some transform faults can be seen at Earth's surface. For
example, the San Andreas Fault in California is visible in many
places. An area of many fractured pieces of crust along

a large fault is called a fault zone.

Landforms created by shear are not as obvious as landforms created by tension or compression. Transform boundaries

are characterized by long faults and fault zones. When rocks move along faults, earthquakes can suddenly occur.