Plate Tectonics Earth’s Interior Convection Currents Sea Floor Spreading Plate Boundaries Hot Spots

Objective(s): List the layers and properties of the interior of the Earth Relate plate tectonic evidence to Continental Drift List and describe plate movements and interactions

DO NOW How many mm are in a cm? 10! So, 1 cm is the same as __________mm. If from my room to the library is 20 meters and from the library to Mr. Doyle’s room is 50 meters, how many meters do I have to walk to get to Mr. Dolye?

Earth’s Interior Includes the crust to the center of the Earth http://sciencerevolution.net/dict_m.html

Crust UPPER MANTLE Coolest in Temperature Least Dense Two Parts: Continental Thicker Mostly Granite Less Dense 2.7 g/cm3 Oceanic Thinner Mostly Basalt More Dense 3.0 g/cm3 Crust http://earthquake.usgs.gov/learn/glossary/?termID=57 LITHOSPHERE UPPER MANTLE

Mantle Upper Mantle (Rigid) Asthenosphere (Plastic Mantle) Part of the lithosphere Asthenosphere (Plastic Mantle) Mushy Allows the lithosphere to move Lower Mantle (Rigid)

Outer Core Liquid! Composed of Iron (Fe) and Nickel (Ni) Not under enough pressure to be solid Composed of Iron (Fe) and Nickel (Ni) Believed to be the source of Earth’s Magnetic Field Protects us from Solar Winds which would destroy our atmosphere and make us as lifeless as Mars

Inner Core Solid Composed of Iron (Fe) and Nickel (Ni) Most Dense Increased pressure causes this layer to be solid unlike the outer core Composed of Iron (Fe) and Nickel (Ni) Most Dense Greatest in Temperature

DO NOW What happens to the density of a material when you heat it? Density decrease What causes the lithospheric plates to move? Convection currents Which part of the mantle does this occur? aesthenosphere

DO NOW What are the four layers inside the Earth ? Crust, mantle, outer core, inner core Which layer is responsible for the plates moving? Asthenosphere Why? This layer is “mushy” therefore allowing movement called convection currents

DO NOW What are the two types of crust? Continental and oceanic Which is thicker, which is more dense? Continental thicker and less dense Which layer is liquid? Outer core Why isn’t the inner liquid if it is the hottest? Too much pressure pushes the molecules together

The Theory of Plate Tectonics Convection cells occur inside the Earth’s mantle cause crustal movement. These convection cells are thought to be like conveyor belts, which would cause the rock above to move and shift. It solves Alfred Wegener’s biggest flaw!!

Convection Currents Currents in the mantle are thought to be responsible for the movement of the lithospheric plates Movement of heat in mantle due to differences in density HOT = Less dense and RISES COOL = More dense and SINKS

Sea Floor Spreading The ocean floors are spreading apart as new rock material is added to the crust in the regions of mid-ocean ridges

Continental Drift – Seafloor Spreading Connection!! Alfred Wegener’s missing evidence: Seafloor spreading explains how the continents move (in addition to convection currents) The continents are on plates, which move over the asthenosphere http://app.discoveryeducation.com/player/?assetGuid=AE10AA7D-5660-4758-B668-E36ADA60644C&fromMyDe=0&isPrinterFriendly=0&provider=&isLessonFromHealth=0&productcode=US&isAssigned=false&includeHeader=YES&homeworkGuid=

Where’s the Evidence? Age of Igneous Rock on Ocean Floor The sea floor is younger at the ridges and gets older as you move towards the continents Reversal of Magnetic Polarity Igneous rocks at the mid-ocean ridge show magnetic orientation of Earth’s magnetic poles when the rock solidifies

Magnetic Polarity Normal Polarity Reverse Polarity The compass needle would point to north This is the magnetic orientation of Earth today Reverse Polarity The compass needle would point to south Not today’s magnetic field, but has occurred in the past many times

Plate Boundaries Where the edges of plates meet Three types Divergent Convergent Transform

Types of Plate Boundaries 1. Divergent Plate Boundary Where plates move apart Geologic Features Found Here: Rift Valley Volcanoes Earthquakes Examples: Mid-Atlantic Ridge Great Rift Valley in Africa

Mid-Atlantic Ridge

2. Convergent Plate Boundary Where plates move towards each other Oceanic – Continental Oceanic – Oceanic Continental – Continental Geologic Features and Activities Found Here: Mountains On Continents Volcanoes Earthquakes Trench Deepest part of the ocean Example: Tonga Trench

Subduction Zones The area where two plates collide together (Converge) and one of the plates (Subducting Plate) is forced down into the mantle where it will be destroyed Subducting Plate The plate that is being forced down This creates volcanoes EX: Andes mountains in South America contains many volcanoes

Oceanic – Continental

Oceanic – Oceanic Islands of Japan were formed this way

Continental – Continental No subduction – Plates crumple up forming mountains.

Himalayan Mountains

Transform (Sliding) Boundaries Where plates slide past one another Geologic Activity Found Here: Earthquakes Example: San Andreas Fault

San Andreas Fault https://www.youtube.com/watch?v=Kg_UBLFUpYQ Plate tectonics 14 min

EARTHQUAKES http://www.youtube.com/watch?v=dkELENdZukI

Elastic Limit When rock reaches its elastic limit an earthquake occurs. When rock breaks they move along surfaces called faults. This movement creates vibrations in the ground.

earthquakes Occur at plate boundaries Convergent: Plates move together Divergent: Plates move apart Transform: Plates are sliding http://hsv.com/scitech/earthsci/quake.htm