Spheres of Function

•Earth can be divided into spheres that are defined
according to their location and function.

Lesson 3.2 Systems in Environmental Science

The Geosphere

•Crust: Thin, cool, rocky outer “skin”

•Mantle: Very hot and mostly solid

•Core: Outer core is molten metal, inner core
is solid metal

Lesson 3.3 Earth’s Spheres

•Rocks and minerals on and below Earth’s surface:

Plate Tectonics

• Crust and mantle are divided into:

•Lithosphere: Crust and uppermost mantle;
divided into tectonic plates
•Asthenosphere: Soft middle mantle; heated
by outer core
•Lower mantle: Solid rock

• Convection currents in the asthenosphere move

tectonic plates.

• Collisions and separations of the plates result in

landforms.

Lesson 3.3 Earth’s Spheres

Tectonic Plates

•There are three major types of plate boundary:

•Divergent

•Transform

•Convergent

Lesson 3.3 Earth’s Spheres

Divergent and Transform Plate

Boundaries

• Divergent boundaries:

Rising magma pushes
plates apart.

• Transform boundaries:

Plates slip and grind
alongside one another.

Lesson 3.3 Earth’s Spheres

Divergent plate boundary

Transform plate boundary

Convergent Plate Boundaries

•Plates collide, causing one of two things to happen:

•Subduction: One plate slides beneath another.

•Mountain-building: Both plates are uplifted.

Lesson 3.3 Earth’s Spheres

•Biosphere: The part of Earth in which living and
nonliving things interact

•Atmosphere: Contains the gases that organisms
need, such as oxygen; keeps Earth warm enough
to support life

The Biosphere and Atmosphere

Lesson 3.3 Earth’s Spheres

The Hydrosphere

•Consists of Earth’s water

•Most of Earth’s water (97.5%) is salt water.

•Only 0.5% of Earth’s water is unfrozen fresh water
usable for drinking or irrigation.

•Earth’s available fresh water includes surface water
and ground water.

Lesson 3.3 Earth’s Spheres

Did You Know?If it is depleted, groundwater can
take hundreds or even thousands of years to
recharge completely.

The Water Cycle

Lesson 3.3 Earth’s Spheres