GRADE 9 / GEOGRAPHY / THE EARTH
What are the layers of the earth?
1. Crust 2. Mantle 3. Outer core 4. Inner core
How do scientists study the earth's interior?
1. Mining (analyze the depth/width of the layers of the earth) 2. Study earth's magnetic poles 3. Send sound waves through the earth
What is the Core divided into?
1. Outer Core 2. Inner Core
List three types of Rocks:
1. Sedimentary 2. Metamorphic 3. Igneous
What are the parts of the CRUST?
1. upper 2. lower
What are the characterisitics of igneous rocks?
>Formed from the solidification of magma. >Crystal sized. >Strong because of mineral grains grow together tightly as they cool.
What is located above the inner core of the earth?
A shell of liquid iron, called the outer core.
How do sedementary rocks form?
By particles of sand, shells, pebbles and other fragments of material.
What is the LITHOSPHERE?
Collectively It is made up of 3 things: Upper crust, lower crust & upper-most part of the Mantle
Describe the inner core:
Composed mostly of Iron, plus substantial amounts of sulfur and nickel. It creates the earth's magnetic field and is about 1400 miles (343 km) thick.
How do metamorphic rocks form?
From under the sruface of the earth from metamorphosis.
What does the Upper Crust do and what is it formed of?
It forms the continents and is made of silica aluminum (SIAL).
Describe the Mantle
It is approximately 2900 kms thick and consists of rocks that are much heavier than those that make up the crust.
Describe the outer core:
It is cooler thant the inner core, but still very hot, perhaps 4,000 to 5,000 degrees celsius (7,200 to 9000 degrees farenheit)
What does the Lower Crust do and what is it formed of?
It is found below the continents and water bodies on the earth's surface. It is more dense and heavier than the upper crust. It is made of silica and magnesium (SIMA).
What is Magma?
It is made up rocks that are reduced to liquid (by the great heat inside the earth).
What are the types of rocks the earth is made of?
Semi-molten (partially melted) & Liquid form
What is the earth made of?
Several layers of rocks in different states.
What are rocks?
Solid/Minerals that make up the earth's crust
What is the Core of the earth?
The centeral or inner-most layer of the earth.
What causes rocks to melt?
The great heat inside of the earth.
Athenosphere
The soft layer of the Mantle on which the tectonic plates move. This is made up of the upper mantle.
What is the MANTLE?
The thick layer of semi-molten rocks that is found below the crust.
What is the HYDROSPHERE?
The water on the earth's surface and in the atmostphere.
What are the temperatures & pressure like in the earth's core?
They are extremely high and great pressure is exerted by the layers of rocks above.
How do scientists describe the the state of the earth's core?
They are uncertain, but they theorize that: 1. The outer-core is liquid and the inner core is solid. 2. Although the inner core is white hot, the pressure is so high that the iron cannot melt.
How do igneous rocks form?
When magma cools and hardens
