Moho line, Lithosphere, Aesthenosphere, Draw and label the structure/layers of the Earth. Describe both the physical and chemical properties of them. 2. What evidence is used to support the existence of these structures? 3. What is significant about the “outer core”? 4. Explain the connection between: Moho line, Lithosphere, Aesthenosphere, convection currents 5. Differentiate between the 2 types of crust. 6. Explain the concept of isostacy. Give an example of when it has/would occur.

Differentiation of the Earth……. produces Earths’ internal structure Crust, Mantle and Core

PHYSICAL PROPERTIES CHEMICAL PROPERTIES

Chemical Differentiation of the Earth

VIDEO: When North Goes South

Structure of the Earth It is composed of a number of different layers as determined by deep drilling and seismic evidence Common elements found in the lithosphere Oxygen   46 %  Silicon   27 %   Aluminum  8 % Iron  5 %   Calcium   3 % Sodium   2 % Potassium   2 %  Magnesium   2%

Variations occur due to temp & density differences “Seismology” “Seismic Tomography”

THE CORE Inner core is theorized to be solid and a radius of about 1220 kilometers. Rich in iron and nickel The outer core is liquid and has an average thickness of about 2250 kilometers. It creates Earth’s magnetic field

THE MANTLE 2900 kilometers thick and comprises about 83 % of the Earth's volume.

The upper mantle exists from the base of the crust downward to a depth of about 670 kilometers. Rocks in this upper portion of the mantle are more rigid and brittle because of cooler temperatures and lower pressures.

The lower mantle extends from 670 to 2900 kilometers below the Earth's surface. This layer is hot and plastic. The higher pressure in this layer causes the formation of minerals that are different from those of the upper mantle.

THE LITHOSPHERE Includes the crust and the upper most portion of the asthenosphere 100 kilometers thick – brittle & solid Zone of earthquakes, mountain building, volcanoes, and continental drift. Lithospheric plates ride on a weak, plastic zone below known as the asthenosphere, which is capable of flow.

Asthenosphere Beneath the lithosphere, materials show a more plastic response to stress. If you could hold some asthenosphere in your hands and squeeze it, it would flow in a manner similar to silly putty.

Upper Mantle and Crustal Structure Moho Continental Oceanic Upper Mantle and Crustal Structure Lithosphere (or plate) = crust + uppermost, rigid part of the mantle

Earth’s Crust Landforms are not permanent Constantly changing in geologic time (eras of 10-100’s of millions of years) Major Forces of Change: GRADATIONAL Powered mainly by solar energy Wear down tectonic created shapes & irregularities TECTONIC Powered mainly by energy from Earth’s interior Alter crust by producing shaped & irregularities

THE CRUST OCEANIC CRUST Thin Young (-200 million yrs) 5 to 10 kilometers thick Composed of basalt Density of about 3.0 grams per cubic centimeter. CONTINENTAL CRUST Thinnest in areas like the Rift Valleys of East Africa Thickest beneath mountain ranges Older – up to 3.9 Billion yrs 20 to 70 kilometers thick Composed mainly of lighter granite Density of about 2.7 grams per cubic centimeter

THE CRUST (“FELSIC”) (“MAFIC”) CONTINENTAL CRUST OCEANIC CRUST Lighter, diverse, older – Silicon, Aluminum (“MAFIC”) Heavy, dark, Basaltic, younger – Silica, Magnesium, Iron

Passive Boundary

Constructive and Destructive Boundaries Convection currents within the mantle cause these plates to move slowly across the asthenosphere Constructive and Destructive Boundaries

OCEANIC & CONTINENTAL PLATES

SUBSIDENCE/DISPLACEMENT: ISOSTACY Continental and oceanic crust have the ability to rise and sink. The crust floats on top of the mantle like ice cubes in water. SUBSIDENCE/DISPLACEMENT: When the Earth's crust gains weight (mountain building or glaciation) it deforms and sinks deeper into the mantle REBOUND: If the weight is removed, the crust becomes more buoyant and floats higher in the mantle.

Weight of ice causes crust to deform & sink After melting – Rebound occurs Crust rises to former pre-glacial position

Effects Of Erosion

Isostatic Rebound results in deeply buried rocks becoming exposed at the surface. (eg. intrusive granite, folds)

CRATONS The relatively stable core of a continent that is not currently affected by tectonics along plate boundaries. Usually consist of highly deformed metamorphic rock that formed during ancient orogenic explosions. Exist in the hearts of all the continents, a typical example being the Canadian Shield.