Building Up and Breaking Down

When the crust moves, the rocks of the crust can change. They can change position. These changes may cause mountains to be made. The most common type of mountain is made mostly of rock layers folded by being squeezed together. This is called a fold mountain. A fault is a large crack in rocks along which there is movement. A mountain made by huge tilted blocks of rocks separated from surrounding rocks by faults is called a fault-block mountain. At the same time that forces are building up the crust, other forces are breaking down the crust. The two main forces breaking down the crust are weathering and erosion. The breaking down of rocks into smaller pieces by natural processes is called weathering. The picking up and removal of rock fragments and other particles is called erosion.  The end result of weathering is soil. Soil is a mixture of weathered rock, decayed plant and animal matter, living things, air, and water.  Plants and animals live in and on the soil. When they die, their remains enrich the soil. Rocks in the soil break down into smaller and smaller pieces.  Slowly the soil develops distinct layers. Any of the layers of soil from the surface to the bedrock below are called soil horizons. Below the soil is weathered rock and rock layers. Water that soaks into soil and rock by collecting in the spaces between the rock particles is called groundwater.  Poor soil can be improved by adding fertilizers. It can also be improved by adding humus. Humus is material in soil produced by the breakdown of plant and animal material. Humus helps soil absorb and retain water. And is what I learn.

Vocabulary#14 Volcanoes

Hot spot:A very hot part of the mantle, where magma can melt through a plate moving above it.
S:As a plate moves over the hot spot,magma melts up through the crust and form volcanoes.

Vent:A central opening in a volcanic area through which magma may escape.
S:The magma escape from th vent in a volcanoe.

Lava:Magma that reaches Earth`s surface and flows out of a vent.
S:The Lava is like a magma that flows out the vent.

Crater:A cuplike hollow that forms at the top of a volcano around the vent.
S:When a volcano collapses it form a crater.

Cinder-cone volcano:A steep-sided cone that forms from explosive eruptions of hot rocks,ranging from particles to boulders.
S:Italy`s Stromboli is a cinder-cone volcano.

Shield volcano:A wide ,gently sloped cone that forms from flows of lava.
S:Hawaii`s Mauna Loa is a shield volcano.

Composite volcano:A cone formed from explosive eruptions of hot rocks followed by a flow of lava,over and over.
S:Shishaldin is a composite volcano.

Geothermal energy:Heat from below Earth`s surface.
S:Today scientist are finding ways to use geothermal energy.

Vocabulary#13 Earthquakes

Fault:A huge crack in the crust,at or below the surface,the sides of which may show evidence of motion.
S:Faults are huge cracks in the crust.

Focus:The point where an earthquake starts,where rocks begin to slide past each other.
S:The focus is usually below the surface.

Seismic wave:a vibration that spreads out away from a focus when an earthquake happens.
S:The vibrations travel through the crust in seismic waves.
 
Epicenter:The point on Earth`s surface directly above the focus.
S:The epicenter that people can feel the ground shaking.

Aftershock:The shaking of the crust after the initial shaking of an earthquake.
S:Aftershocks continue the damage of an earthquake.

Seismograph:A sensitive device that detects the shaking of the crust.
S:Seismograph is a tool to detects the shacking of the crust.

Magnitude:The amount of energy released by an earthquake.
S:The Richter Scale rates earthquakes from 1 to 10 according to magnitude.