Download Changes to Earth`s Surface

Changes to
Earth’s Surface
Changes to Earth’s Surface
 The
surface of the Earth is constantly
changing. Some changes happen quickly and
can be dangerous. Others happen so slowly, you
would have to live for thousands of years to
notice even a small difference.
Slow Changes: Weathering
 Weathering
is the breakdown of rocks into
sediments and minerals
 Minerals are nonliving, solid materials that
are formed in nature and made of crystals.
Rocks are made of different types of minerals.
Minerals
Rocks
Slow Changes: Weathering
 Weathering
forces.
is caused by different physical
 Water
and ice
 Plants and animals
 Chemical reactions
 Built up pressure
 Weathering
produces
sediments, or small
pieces that break off of
rocks.
 Examples
of sediments are
pebbles, sand, silt, and mud.
Slow Changes: Erosion
 Erosion
is the movement
of sediment by wind,
water, ice, or gravity.
 Runoff, creeks,
streams, and rivers
pick up and carry
sediment away. This
can weather the
landscape in dramatic
ways.
Slow Changes: Erosion
 The
overuse of land by humans can have an
impact on the Earth’s surface. When humans
clear land, the bare soil erodes easily.
Slow Changes: Erosion
 Glaciers
are gigantic formations of ice that do
not completely melt over the course of a year.
Glaciers can erode rock, grind mountains into
valleys, and carve out lakes.
Slow Changes: Erosion
 When
sediments land
somewhere else and
stay for a while, it is
called deposition. Lots
of sediment is
deposited at the mouth
of a river. A growing
pile of deposited
sediment at the mouth
of a river is called a
delta.
The Nile River Delta
Bill Nye: Erosion
 http://www.youtube.com/watch?v=D7WFeh30U
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Rapid Changes to Earth’s Surface
 Some
changes to the Earth’s surface happen
rapidly, such as fires, floods, earthquakes,
volcanoes, and tornadoes.
 Earth’s crust is like a jigsaw puzzle, made up of
large and small sections called tectonic plates.
Energy from the Earth’s core and mantle pushes
them around so they are in constant, slow
motion. The plates can cause earthquakes and
volcanoes.
 http://www.ucmp.berkeley.edu/geology/anim1.html
Rapid Changes: Earthquakes

Earthquakes are caused by the movement of the Earth’s
plates. When the plates move, they grind against each
other. Earthquakes occur at points where the plates get
stuck. Tension builds, and then the plates move quickly.

http://earthquake.usgs.gov/earthquakes/map/
http://www.weatherwizkids.com/weather-earthquake.htm

Rapid Changes: Volcanoes

Volcanoes are often found along the edges of the plates.
Far beneath the Earth’s surface, high temperatures cause
rock to turn into liquid. The liquid rock is called magma.
Magma escapes from the center of the Earth through
volcanoes. The magma is then called lava.
Rapid Changes: Flooding
 Large
amounts of rain can cause flooding.
Flooding can damage natural areas and manmade structures. However, flooding can
sometimes have a positive effect on soil.
Rapid Changes: Drought
 When
an area does not get enough rain for an
extended period of time, it experiences a
drought. As a result of this water shortage,
many plants and animals die.
Rapid Changes: Fires


When the land is too dry, forest and grass fires are easily
started. Many of the fires in nature are caused by humans,
but some are caused by lightning. Fires can destroy animal
habitats, decrease water supply, and leave the land open to
erosion.
However, fires can be helpful to plant growth. Fire gets rid
of the dead underbrush, clearing the land for new plant
growth.
Studying Environmental Changes:

The greenhouse effect causes a gradual increase of
temperature around the world. This increase is
known as global warming. The temperature melts
ice caps, causing the sea level to rise. When the sea
level rises, flooding can occur along the coasts.

Video:
http://www.epa.gov/climatestudents/basics/today/g
reenhouse-effect.html
Studying Environmental Changes:
 Scientists
use different types of evidence to learn about
how the environment has changed

When a tree is cut, you can see growth rings. The tree
rings tell you how old the tree is. Wider rings indicate a
warm wet season, and thinner rings indicate dry seasons.
Studying Environmental Changes:
 When
sediments cover dead plants or animals, fossils
can form. Fossils are the remains or traces of animals
and plants that lived long ago. Fossils allow people to
study organisms that have been extinct for thousands
or millions of years. Scientists date the fossils by where
they were found in the layers of rock. The bottom layers
of rock are older than the top layers.
Rock Layers of the Grand Canyon
Studying Environmental Changes:
 Ice
cores can be used to learn
about changes in the climate
of ice regions. Long, narrow
pieces of ice are drilled from
the ground and removed.
Bands of light and dark snow
can be seen. The older snow
is at the bottom, and the
newer snow is on top. Air
bubbles from hundreds of
years ago are trapped in the
layers.