1. 4th grade Earth Science Part 2
L.O. I will describe what reshapes land and how this happens.

2. Day 1 Fast Changes in Earth
Earthquakes
*A fault is a crack in the Earth’s crust
The two sides are called plates
*During an earthquake, one of three things will happen:
the plates push against each other and will slide along each other
the plates push against each other and one side will go on top of the other
the plates pull apart

3. The epicenter is where an earthquake is felt most strongly
Tsunami is a very large ocean wave caused by an earthquake on the ocean floor

4. Volcanos
Opening in Earth’s crust
Hot ash, gases, and molten rock escape from deep within Earth
Molten rock beneath Earth’s surface is called magma
When magma reaches Earth’s surface, it is called lava
*Hawaii was formed by volcanoes

5. *Landslides – the sudden movement of loose rock and soil down a steep slope
The steeper the slope, the faster the soil and rock will move downhill
*4 main things cause landslides:
Heavy rains
Sudden melting of snow
Earthquakes
Volcanic eruptions

6. Day 2 Slow changes in Earth
*Weathering is when rocks slowly wear away into smaller and smaller pieces by water, snow, wind, and rain
*Erosion moves these sediments (rock pieces) that were a result of weathering from one place to another

7. As moving water flows, it loosens and picks up the tiny particles that have been left by the weathering and carries it down stream or to other places – called erosion
*Therefore, Moving Water causes landforms to erode
*Wind carries bits of rock and soil in the air – so wind causes erosion
*Moving water and wind cause erosion which created Grand Canyon

8. *5 things cause rocks to break into smaller pieces
*The first three are the main causes
*Continual freezing and thawing ice
*Plant roots
*Moving water
Heat mixed with rain
chemicals

9. Freezing and thawing
Most rocks have tiny cracks in them
Water gets into the cracks
When it freezes, it expands
Pushes the crack, making it a little bigger
Melts
Refreezes, pushing crack to make it bigger
Eventually this process will cause the rock to break

10. Plant roots
Roots are small and grow into cracks
Over time, as the root grows it spreads the crack wider
Eventually, the rock will break

11. Rocks that are exposed to or in moving water such as streams constantly bump against other rocks, wearing down sharp edges and becoming smooth and smaller