Download Planet Earth - Topic 2 (ANSWERS)

Unit # 5 - PLANET EARTH
Name: __________________
TOPIC 2 – ROCKS AND THE ROCK CYCLE
1. Scientists have grouped rocks into three major families they are igneous, sedimentary and
metamorphic rocks. Each can be identified by its appearance.
*Type I - Igneous rock forms when hot magma or lava cools and solidifies.
3. Magma is melted rock found below the Earth’s crust, where temperatures and pressures are very high.
Any rock heated at great depths can melt into magma. Magma can push away or dissolve surrounding
rocks.
4. When magma breaks through the Earth’s surface, in the form of a volcanic eruption, it is called lava.
5. How is intrusive rock formed? Where is it formed? Give an Example.
How
Where
When rock/magma underneath the Earth’s surface cools.
Example
Granite
6. How is extrusive rock formed? Where is it formed? Give an Example.
How:
When lava cools/hardens above the Earth’s surface.
Where:
Example:
Obsidian
7. What is the relationship between the size of a crystal and the length of time it took to form?
The longer the crystals take to form, the larger the size of the crystal.
8. Igneous comes from the Latin word ‘ignis’ meaning fire. p.361
*Type II - Sedimentary rock is made of sediments - loose material, such as bits of rock minerals,
plants and animals remains. These sediments become closely packed in layers and cemented together.
This arrangement of visible layers is called stratification
.
10. Define compaction.
Process of which sedimentary rock is formed from sediment. Takes a long time and requires pressure
from water and other sediments.
11. Define cementation.
Like compaction, but it includes large pebbles and rocks.
*Type III - Metamorphic rock means changed form. Metamorphic rock may be formed below the
Earth’s surface when extremely high pressure and heat cause the original rock, or parent rock to change
form. For example shale changes to slate which changes to schist. Another example of Metamorphic
Rock is Marble
14. Draw the Rock Cycle and explain how it works. p. 368 (explain all arrows)
* All families in the Rock Cycle can become each other under the right conditions!(heat, pressure, etc)
16. Soil can take thousands of years to form. A soil profile is a view of the different layers that make up
soil. p. 372
Topsoil is the top layer of soil, which is often rich in humus & nutrients.
Leaching is the removal of soil material dissolved in water.