Chapter 7-Section 1 Earth’s Moving Plates

Layers of the Earth List the layers of the earth in order from the exterior to the interior- in your notebook Crust Lithosphere Asthenosphere Mantle Outer core Inner core

Clues to Earth’s Interior Geologists must use indirect observations Geologists also study- to gather clues about what Earth’s interior is made of earthquakes and rocks that are exposed at Earth’s surface the speed of waves and the paths they take Certain rocks from different places on the Earth’s surface

Earth’s Layers Earth’s interior has at least 4 distinct layers inner core, outer core, mantle, and crust

Inner Core Inner core Innermost layer Solid-dense-composed mostly of solid iron Hottest part Experiences the greatest amount of pressure

Outer Core Outer core Lies above the inner core Composed mostly of molten metal liquid

Mantle Mantle Above the outer core Largest layer Flows slowly-similar to putty 82% of Earth’s total volume

Crust Crust Earth’s outermost layer Thin compared to other layers Contains all features of the Earth’s surface

Earth’s Plates-Lithosphere rigid, upper part of Earth’s mantle and the crust broken into about 30 sections, or plates Sections of Earth’s crust and rigid, upper mantle that moves slowly around on the asthenosphere

Plate tectonics Tectonics – Theory of plate tectonics – structural deformation of the Earth's crust (Note: prefix “de” means to undo) scientific theory explaining how the plates move on the Earth’s surface

Tectonic Plates http://www.youtube.com/watch?v=nfziy_860GU

Scientific fact, law, theory Scientific law – Scientific theory – statement that is accepted as being true. statement that describes an observed phenomenon but does not explain how or why it occurs. statement that explains a complex idea.

Plate Movement

http://www.youtube.com/watch?v=gyT8Xs6Ab-k

Plate Boundaries Plate boundaries- Boundaries can form- Faults- Where the edges of different plates meet mountains, huge rift valleys with volcanoes, or faults (which cause earthquakes) large fractures in rocks along which movement occurs http://www.learner.org/interactives/dynamicearth/drift.html

http://www.youtube.com/watch?v=mB2pzhWUaiU&feature=related

Plates that move apart When plates move apart- New lithosphere and mid-ocean ridges form Volcanic activity Rift valleys Divergent boundary http://www.learner.org/interactives/dynamicearth/slip3.html

Divergent Boundary

Ocean Basin Ocean basin a great depression in the surface of the lithosphere occupied by an ocean are below sea level. The Atlantic Ocean has an actively growing ocean basin where as the Pacific Ocean has a actively shrinking ocean basin.

http://www.youtube.com/watch?v=K8blL9Ki2mQ

http://www.youtube.com/watch?v=nfziy_860GU

Plates that collide When plates collide Convergent boundary http://www.learner.org/interactives/dynamicearth/slip2.html

3 types of convergent plate boundaries Mountains/shallow earthquakes Continental-continental collisions may cause-

3 types of convergent plate boundaries Continental-oceanic collisions (subduction) may cause- Earthquake activity, volcanic eruptions, volcanic mountains, tsunamis, ocean trench

3 types of convergent plate boundaries Oceanic-oceanic collisions (subduction) may cause-  earthquakes, oceanic trench, a chain of volcanic islands

Plate Subduction Plate subduction- At a convergent boundary-when one plate sinks underneath another plate http://www.jclahr.com/science/earth_science/animate/subduct.mov

Plates that slide past When plates slide past each other transform boundary Causes faults-which leads to earthquakes http://www.learner.org/interactives/dynamicearth/slip3.html http://www.learner.org/interactives/dynamicearth/plate.html

Ring of Fire https://www.youtube.com/watch?v=wJS7hGMr0Ws http://www.youtube.com/watch?v=YqSJDNi7Qzw&feature=related

Why do plates move? Scientists suggest Convection currents

Here is a simulation of convection in the mantle of the earth Here is a simulation of convection in the mantle of the earth. Hot rock (yellow) rises and cool rock (blue) falls. The rock is at 1000 to 2000o C and creeps slowly; the rate of motion is a few centimeters per year (the simulation shows millions of years). The convection occurs because of the slow change of density with depth in the upper mantle, and between the 700 and 400 km discontinuities. As a result, a hot zone of rock at the bottom of one of these zones expands enough so its density becomes less than that of the surrounding rock and it rises, or floats, toward the surface of the earth. 

Earth in the Past and Future https://www.youtube.com/watch?v=uGcDed4xVD4 https://www.youtube.com/watch?v=38DMH3zP97U