Presentation on theme: "Earths Interior. Geology : the study of planet Earth Geologists study the processes that create Earth’s features and search for clues about Earth’s."— Presentation transcript:
Geology : the study of planet Earth Geologists study the processes that create Earth’s features and search for clues about Earth’s history Geologists have to make predictions about what the Earth’s interior is made of by making indirect observations of seismic waves Forces beneath the Earth’s surface change the Earth’s appearance. There are two types of forces:
Constructive: forces that build up mountains and landmasses Destructive: forces that destroy mountains and other features of land
Continents: the seven great landmasses surrounded by oceans the seven continents: 1. North America 2. South America 3. Africa 4. Europe 5. Asia 6. Australia 7. Antarctica
Use seismic waves : vibrations that travels through Earth, carrying the energy released during an earthquake determine the speed and path of these waves to reveal the inner Earth’s structure
Crust : Layer of rock that forms Earth’s outer skin (made of Oxygen, Silicon, Aluminum, Calcium, Iron, Sodium, Potassium and Magnesium) Includes soil and water 8-40 km thick Oceanic Crust: crust beneath the ocean Thin layer of crust Made of- basalt: dark dense rock with a fine texture Continental Crust: crust that forms the continents Thicker layer of crust Made mainly of granite, which then weathers and redeposits into many sedimentary and metamorphic rocks
Mantle: a layer of hot rock under the Earth’s crust (made of a material called peridotite which is high in iron and magnesium) Lithosphere: a rigid layer made up of the uppermost part of the mantle and the crust; about 100km thick- (tectonic plates) Under the Lithosphere is a layer of hot rock Temperature and pressure in the mantle increase with depth Asthenosphere: thick, soft material that flows in the mantle; about 3,000km thick; moves in a convection current
Core : innermost layer of Earth; consists of 2 parts (made of iron and nickel) 3. Outer Core layer of molten metal that surround the inner core Behaves like a thick liquid Is under enormous pressure 4. Inner Core Dense ball of solid metal Extreme pressure makes it a solid
The Earth has a magnetic field that is caused by the inner core spinning within the outer What is this magnetic field called?
The crust is a very thin layer compared to the others.
We already know that over time, the Earth’s crust cooled. The crust is thin, relatively, varying from a few tens of kilometers thick beneath the continents to less than 10 km thick beneath the oceans. The crust and upper mantle together constitute the lithosphere, which is typically km thick and is broken into large plates. These plates sit on the asthenosphere. The asthenosphere is kept plastic largely through heat generated by radioactive decay. This heat source is relatively small, but nevertheless, because of the insulating properties of the Earth's rocks at the surface, this is sufficient to keep the asthenosphere plastic in consistency.
Heat Sources in the Earth 1. Heat from the early accretion and differentiation of the Earth u still slowly reaching surface 2. Heat released by the radioactive breakdown of unstable nuclides
Heat Transfer 1. Radiation 2. Conduction 3. Convection
If you look at a map of the world, you may notice that some of the continents could fit together like pieces of a puzzle.
The Earth’s crust is divided into 12 major plates which are moved in various directions. This plate motion causes them to collide, pull apart, or scrape against each other. Each type of interaction causes a characteristic set of Earth structures or “tectonic” features. The word, tectonic, refers to the deformation of the crust as a consequence of plate interaction.
Below the lithosphere (which makes up the tectonic plates) is the asthenosphere.
“Plates” of lithosphere are moved around by the underlying hot mantle convection cells
Divergent Convergent Transform Three types of plate boundaries
Spreading ridges As plates move apart new material is erupted to fill the gap Divergent Boundaries
Age of Oceanic Crust Courtesy of
Iceland has a divergent plate boundary running through its middle Iceland: An example of continental rifting
There are three styles of convergent plate boundaries Continent-continent collision Continent-oceanic crust collision Ocean-ocean collision Convergent Boundaries
Forms mountains, e.g. European Alps, Himalayas Continent-Continent Collision
Called SUBDUCTION Continent-Oceanic Crust Collision
Oceanic lithosphere subducts underneath the continental lithosphere Oceanic lithosphere heats and dehydrates as it subsides The melt rises forming volcanism E.g. The Andes Subduction
When two oceanic plates collide, one runs over the other which causes it to sink into the mantle forming a subduction zone. The subducting plate is bent downward to form a very deep depression in the ocean floor called a trench. The worlds deepest parts of the ocean are found along trenches. E.g. The Mariana Trench is 11 km deep! Ocean-Ocean Plate Collision
Where plates slide past each other Transform Boundaries Above: View of the San Andreas transform fault