Download processes that shape the earth

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EARTH SCIENCE ~ PART 1
WHAT THE EARTH LOOKS LIKE (pgs. 204-206)
 Earth is known as the blue planet because about 70 percent of the Earth’s surface is covered
with water and most of that is the ocean. Only a small amount of the Earth’s water is
freshwater, which is found in rivers, lakes and ground water.
 Mountains ~ the tallest and most visible kind of landform.
 Plains ~ the flattest kind of landform, vast areas of land without hills or mountains.
 Valleys ~ strong flows of water cut into the land.
 Canyons ~ formed by rivers that cut narrow, steep sided valleys.
 Deltas ~ a landform that forms from deposition of sediment carried by a river as the flow
leaves its mouth and enters slower-moving or standing water. This occurs where a river
enters an ocean, sea, estuary, or lake.
LAYERS OF THE EARTH (pg. 208)
 Crust ~ the thinnest layer of the Earth, made up of solid rock. It is the outermost layer.
 Mantle ~ the thickest layer of rock lying below the crust. Rocks can move or slowly flow
because of great pressure and high temperatures.
 Core ~ the outer layer is liquid, while the inner layer is solid.
 Think of a hard-boiled egg. The shell is like the crust, the white part of the egg is like the
mantle, and the yolk is like the core.
THE MOVING CRUST (pgs. 214-220)
 Plates ~ the Earth’s surface is made up of several pieces that fit together like the pieces of a
jigsaw puzzle. They are made of the crust and the upper part of Earth’s mantle. When the
mantle flows, the plates move.
 Plates can move in three ways.
o Away from each other ~ valleys and sometimes mountains form here. When
two plates move away from each other, new earth material rises up from below
the surface. The Mid-Atlantic Ridge is a mountain range on the bottom of the
ocean that is forming this way.
o Slide by each other ~ some mountains along the San Andreas Fault in
California formed from this type of movement.
o Toward each other ~ mountain ranges are formed this way. The Himalayas
are a range in Asia. Mount Everest, the tallest mountain in the world, is found
in the Himalayas.
 Faults ~ a crack in the earth’s crust where movement happens.
 Fault-block mountains ~ rocks on either side of a fault can slide up or down creating
these types of mountains.
 Plateau ~ if the lifting is spread over a wide area, a plateau may form.
 Folds ~ a bend in the rock layers.
 Folded mountains ~ when land on either side of a fault scrunch, these folds become
mountains.
EARTH SCIENCE ~ PART 2
FORCES THAT SHAPE THE EARTH ~ There are many different processes that continually build up
or tear down the surface of the Earth. Here are some of those processes:
 1. Earthquakes ~ a sudden shaking of Earth’s crust. (pgs. 216-219)
 It is caused by sudden movement along a fault. With the push and pull of plates, energy
builds up. This energy can be stored in the Earth for years. Once the energy is released, it
causes the land to shake and break up.
 Some faults in Earth’s surface are near the edges of plates. Scientist think earthquakes
occur because of the movements of these plates.
 Earthquakes begin below the ground causing vibrations to move through Earth in all
directions. (think of waves caused by a pebble dropped in water)
 Some earthquakes can happen below oceans. If strong enough, it causes a giant wave called
a tsunami.
 Seismograph ~ scientist study earthquakes using this instrument. It detects and records
seismic waves caused by earthquakes.
 Seismic waves are vibrations caused by earthquakes.
 2. Volcanoes ~ cracks or vent in Earth’s surface from which steam, ash, and lava escape. (pg. 220)
 Magma is the hot melted rock deep inside the Earth.
 Lava is the hot melted rock above the surface of the Earth.
 They can create islands in the ocean and form mountain ranges on land.
 A mountain is formed when part of the land rises above its surroundings. Magma from deep
inside Earth may rise through cracks made when the earth rises. This may form volcanoes.
Volcanoes can build the mountains even higher.
 Hot spots are places where the Earth’s crust is very thin. Magma easily breaks through to
the surface. The Hawaiian Islands were formed over a hot spot in the Pacific Ocean.
 3. Weathering ~ the slow process that breaks rocks down into smaller pieces. Flowing water,
rain, and wind are some causes of weathering. (pgs. 226-227)
 Physical weathering ~ when rocks change size and shape without changing their chemical
makeup.
o Flowing water makes rocks smooth.
o Waves crashing on a cliff break off small pieces of land.
o Plant roots force their way through cracks in rock.
 Chemical weathering ~ changes the minerals that make up rocks. Oxygen, acids, and
carbon dioxide cause chemical weathering.
o Chains of a bicycle get rusty. Water and air change iron into rust.
o Limestone caves are formed by water and carbon dioxide.
 4. Erosion ~ breaking down and washing away of soil and rock by flowing water, waves, wind, or
glaciers. (pgs. 228-229)
 Flowing water ~ rainwater carries particles into rivers and streams. As it flows, it carves
valleys into rock. The Grand Canyon was formed millions of years ago. The Colorado
River carved out this canyon that is 1 mile deep (water erosion).
 Waves ~ pounding waves break up rocks, coral, and shells into smaller pieces. As the
pieces rub against each other, they grind down into particles. Waves carry these materials
away from the shore and drop them in other places. With time, waves can change a
coastline.
 Wind ~ as it blows across Earth’s surface, it picks up small particles of dust, soil, and sand.
With time, exposed rocks and soil are worn down by the particles as if rubbed by sandpaper.
When the wind finally slows down or stops, the particles drop to the ground (wind erosion).
 Hoodoos ~ tall columns of rock shaped by frost and sudden rain.
 Deposition ~ the dropping off of weathered rock. Deposition by water builds up deltas,
riverbanks and beaches. Deposition by wind forms sand dunes.
 5. Glaciers ~ large masses of ice and snow that move over land. (pgs. 230-231)
 They form when more snow fall in the winter than what melts in the summer. With time,
snow collects in layers.
 The weight of the snow and the force of gravity cause the layers to flow downhill. Heat
from friction and from Earth below may melt some of the bottom layer of ice. The thin
layer of water that forms helps the glacier move.
 As they move, they pick up rock debris (boulders, rock fragments, gravel, sand, soil). These
rock fragments in the ice act like sandpaper. They grind away the bedrock, carving deep,
parallel scratches. They can also smooth and polish the rock below.
 Then, when a glacier melts, the rock debris is left behind. Most debris is found at the
bottom and along the sides of a glacier
 The general effect of erosion by glaciers is to flatten and round the land. However, some
types carve out valleys, making them deeper and U-shaped.
 6. Floods ~ an overflow of water onto land that is normally dry. (pg. 238)
 The water doesn’t soak into the ground completely causing it to run on top of the land. The
mud and water cause damage by carrying mud into homes and streets, and washing away
trees and anything in its path.
 7. Fires ~ when there is too little rain, fires are likely to happen. (pg. 238)
 Many fires are caused by lightning.
 Forest fires can destroy acres of land with animals losing their habitats.
 8. Storms ~ a severe storm can change the land. (pgs. 240-241)
 Tornadoes ~ columns of spinning wind. They move across the ground in a narrow path.
As they move, they destroy everything in their path.
o Tornado Alley ~ a certain path through the Great Plains region of the U.S.
 Hurricanes ~ a very large, swirling storm that forms over warm oceans near the equator.
o They are much larger than tornadoes and can span hundreds of kilometers.
o They last longer than tornadoes.
o When they reach land, they cause massive flooding, uproot trees, and flatten
buildings.
o Hurricanes can change an entire ecosystem in one day.
 9. Landslides ~ caused by gravity, they occur when rocks and other materials are shaken loose by
an earthquake or heavy rain. (pg. 242)
 10. Mudflows ~ caused by gravity, they occur after a heavy rain, when the soil can no longer
absorb water.
 11. Avalanches ~ tons of ice and snow rushing down a mountain.