Earths Interior.notebook
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April 15, 2013
Unit 3: Geological Processes
What we will be covering:
Earth's interior structure
Plate Tectonics
Earthquakes and Volcanoes
Earth's surficial processes
Earth's Interior Structure
What do we know already about the interior of the Earth?
Earths Interior.notebook
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Earth's Interior Structure
Note: data given later is to be
considered more accurate than
this diagram in the event of
discrepancies.
Earth's Interior Structure
Despite never having been there in person, or sending a probe, scientists have been able to develop a significant understanding of the internal structure of Earth. They have done this using indirect observations from the surface and above.
Remember that the distance from the centre of the Earth to the surface is Re = 6400 km. The deepest that scientists have drilled anywhere on Earth is 12.2 km, or 0.2% of the distance from surface to core.
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Earth's Core
Earth's core is divided into two parts:
the inner core and outer core
Inner Core
Primarily solid ironnickel alloy
Ric = 1220 km (about 70% the size of the moon)
Tic = approx. 6000 K (similar to the surface of the Sun)
ρic = 13 g/cm3 = 13 000 kg/m3
Point to consider: the average density of the inner core is higher than pure iron or nickel even at great pressure. Why is this?
*Look up the "Iron Catastrophe" and use this event to explain how Earth's interior is differentiated, as well as why we have a magnetic field. Two sources are required.
Earth's Core
Earth's core is divided into two parts:
the inner core and outer core
Outer Core
Similar in composition to Inner Core, however is liquid
Roc = 1220 km to 3480 km (about 2260 km thick)
Toc = 5500 K to 3700 K
ρic = 12.2 g/cm3 to 9.9 g/cm3 = 12 200 kg/m3 to 9900 kg/m3
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Earth's Mantle
Earth's Mantle is the largest feature of
the interior, making up 84% of the volume.
Mantle
Composed of silicate rocks that are rich in iron and magnesium (when compared to the Crust), mostly solid
RM = 3480 km to 6370 km (about 2890 km thick)
Toc = 3200 K to 1500 K
ρic = 5.7 g/cm3 to 3.3 g/cm3 = 5700 kg/m3 to 3300 kg/m3
The top part of the mantle is subdivided into two parts: the asthenosphere and the lithosphere (which also contains the crust)
Earth's Mantle
The Asthenosphere:
a thin, slushlike layer of the mantle
starts approximately 100 km below the surface, extending as deep as 200 700 km
The Lithosphere:
upper most portion of the mantle, as well as the Earth's Crust
rigid layer of rock, which 'floats' upon the asthenosphere
broken into sections: Tectonic Plates
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April 15, 2013
Homework1. Look up the "Iron Catastrophe" and use this event to explain
how Earth's interior is differentiated, as well as why we have a magnetic field. Two sources are required.
2. Draw (or create using a computer) a scale model of the interior of the Earth. Label the layers, along with their temperature and densities (for some layers this will be two numbers for each), as well as their distances from the surface (i.e., the crust goes from 0 65 km).
3. Read Section 8.1 and 8.2 from the text and answer the odd numbered review questions.
Due: _________________
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