Page 126 - Science Course 2 (Book 2)

Mo11-L1b: What Forces Change Earth’s Surface?

Let’s Begin When plates move apart at divergent boundaries, a
rift forms between the two plates.

Tectonic Plate Boundaries A rift can form within continents when continental
crust moves in opposite directions.
The edges of tectonic plates are called plate
boundaries.

A convergent boundary
is where two plates
move toward each
other.

A rift also can form at divergent boundaries on the
A divergent boundary is ocean f oor.
where two plates move
apart from each other. As plates separate, molten rock can erupt from the
rift.

As the molten rock cools, it forms new crust.

A transform boundary
is where plates slide
horizontally past each
other.
Oceanic Crust Continent

When two plates come together, the denser oceanic
plate usually is forced down into the mantle and Upper Mantle Magma
the less dense continental plate remains on Earth’s
surface.

Tectonic plates slide past each other at transform
The area where one plate slides under another is boundaries.
called a subduction zone.
The two sides of the boundary move in opposite
directions.

This can deform or break features such as fences,
railways, or roads that cross the boundary.

When two continents collide at a plate boundary,
both continents remain on the surface.

As two continents push together, the crust rises up
and large mountains form.

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