Chapter 3 Earth Structure and Plate Tectonics. ◦ The inner core is primarily iron and nickel plus other heavy elements. It is theorized to be solid due.

Chapter 3Earth Structure and Plate Tectonics

◦The inner core is primarily iron and nickel plus other heavy elements. It is theorized to be solid due to enormous pressure.

◦The outer core is made up of the same elements. This layer is liquid and its movement is thought to produce earth’s magnetic field.

◦ The mantle is thought to contain mostly silicon and oxygen, with some iron and magnesium. Solid/liquid mixture that moves in convection circles.

◦ The crust is composed mainly of oxygen, silicon, magnesium, and iron. Two types of crust: continental and oceanic. Solid.

Oceanic Crust Denser, thinner and younger than continental crust

Oceanic crust lies lower on the mantle because of increased density.

Continental Crust Lighter, thicker and older than oceanic crust

Continental crust rises higher above mantle because of lesser density.

Color Include all labels Use the text to describe each of the layers:

lithosphere, asthenosphere, lower mantle, core

Use the text to explain how oceanic and continental crust are different.

Lithosphere - _____________Asthenosphere - __________Lower mantle -____________Core – ____________________

Oceanic vs Continental crust_________________________________________________________________________________

Sir Francis Bacon (1600s)and Leonardo DaVinci(1500s)Noticed that the continents seemed to fit

together like a puzzle Alfred Wegener backed up idea with

evidence:Coal deposits and other geological

formations across oceans matchedFossils of a land reptile across oceans also

matchedFossilized tropical plants in Antarctica

States that continents were once joined to form Pangaea over 200 million years ago.

Broke up into pieces and continents float on top of a liquid mantle and are constantly drifting.

Volcanic activity was powered by continental movement.

He incorrectly thought the continents moved because of the rotation of the Earth.

Most detractors did not believe that the continents could float on top of a liquid mantle.

Crust is broken up into lithospheric plates that move on top of the mantle.

The plates move because of convection currents in the mantle.

Plate Tectonics Map by USGS

Zone along the edge of the Pacific Ocean that has many volcanoes and earthquakes.

This horseshoe-shaped belt stretches about 25,000 miles.

Place where crust moves over a mantle plume (column of superheated

mantle). Magma seeps out, cools, and hardens: forms an underwater volcano Magma continues to build up until it breaks the surface of the water forming an

island

Significant because hot spots do not move with tectonic plates because they originate in the mantle.

Volcanic island chains, are the result of the plate moving over a hot spot.

◦ 1. Orderly pattern of oceanic ridges and volcanoes suggesting the Earth’s crust is divided into sections.

◦ 2. Sediment samples – the layers were thin or absent at the oceanic ridges, and thicker away from the oceanic ridges. This suggests newer crust at the ridges.

◦ 3. Radiometric dating was used to determine the age of rocks. Scientists have found seafloor rock to be significantly younger than rock in the center of the continents.

◦ 4. Magnetometer data -This instrument measures the polar orientation of magnetism of minerals. A symmetrical pattern exists in the magnetic alignment in seafloor rock. This pattern radiates outward from the point of seafloor spreading.

Age of Oceanic Rocks: Red = Newest Blue = Oldest

At a spreading or divergent boundary, two plates are moving apart. As this happens, the crust pulls apart and forms valleys. Magma flows up through the rift valleys creating new crust and widening the seafloor.

At a colliding or convergent boundary, two plates push together.◦ They are also called destructive boundaries

because movements along these destroy crust. At a transform boundary or fault, two

plates slide past each other.

Divergent BoundaryDivergent Boundary

Mid-ocean ridges and rift valleys mark divergent boundaries.Cause seafloor spreadingVolcanoes along oceanic ridgesOnly one island above water: Iceland

Because it is on a spreading zone, magma is very near to the surface

This produces hot springs◦ Pools of warm

water at the surface◦Temperatures can

be 150°F and more (very warm bath water)

Oceanic-Oceanic Causes underwater

volcanoes and island formation.

Continental-Continental

collide and “push together” forming mountain chains◦Example: Himalayas

Continental-Oceanic

The oceanic plate is subducted underneath the continental plate

As plate moves down into mantle it melts

Increased magma is forced up through surface forming land volcanoes◦Example: Mount

St. Helens

Also called transform faults or shear boundaries

Plates move side-by-side, but in opposite directions

No sea floor is created or destroyed

Earthquake activity due to friction

◦Example: San Andreas Fault in California

Use the descriptions in table 3.1 pg 75 to draw all the types of plate boundaries.

Divergent Boundaries◦ Ocean-Ocean◦ Continent-Continent

Convergent Boundaries Ocean-Ocean Continent-Continent Ocean-Continent

Transform Boundaries

Illustrations must be colorful, fill the entire poster, show direction of plate movement, label type of boundary, and describe events observed there.