Our Changing Earth Our earth is always changing

Our Changing Earth

Our earth is always changing. Some changes are… SLOW Some changes are… FAST

Scientists think that the surface of the earth has been slowly changing for millions of years. This is the called theory of…

Continental Drift

Some changes to the earth happen… Rapidly!

Landslides

Mudslides

Moving Water

Forest Fires

Earthquakes

Volcanoes u Some volcanoes change the earth quickly. u Some volcanoes slowly build up the land over many, many years.

Glaciers can also slowly change the surface of the earth.

Review Continental drift is theory of how continents move over Earth’s surface.

Pangea was the “Supercontinent” on Earth millions of years ago before the continents “drifted” apart.

ü Weathering is when rock is broken up into smaller pieces called soil, sand, or sediment. üErosion is when the sediment is moved from one place to another. üDeposition is when the sediment is dropped in a new place.

The surface of the earth can change slowly when. . . Lava comes out of a volcano and cools, building up into a mountain over time.

The surface of the earth can change slowly when. . . Glaciers (thick sheets of ice that stay frozen all the time) slowly move, carving the land as they go.

The surface of the earth can change slowly when. . . Water weathers rock as fast moving rivers carve deep canyons in the rock.

The surface of the earth can change slowly when. . . Sediment is moved by water erosion and deposited in a new location. Deltas are made this way.

The surface of the earth can change slowly when. . . water freezes in cracks of rocks. The freezing water expands, and the ice makes the cracks in the rocks bigger. Eventually the rocks break into small pieces.

The surface of the earth can change slowly when. . . Wind carves away bits of rock like a sandblaster.

The surface of the earth can change rapidly when. . . Volcanoes blast away the top or side of a mountain as it erupts.

The surface of the earth can change rapidly when. . . two tectonic plates crash into or slide past each other. This causes an earthquake. Mountains and valleys can be made this way.

The surface of the earth can change rapidly when. . . mass movement occurs. Landslides, mudslides, and sink holes all change the surface of the earth suddenly.

Our earth is changing right now.

Some of the graphics in this presentation may be copyrighted. This presentation is for educational use only.