Earth’s Dynamic Crust & Interior NOTES

What’s inside the Earth?

How do we know what’s inside the earth? Most of what scientists know about the Earth’s interior is inferred based on SEISMIC DATA waves from earthquakes

The properties of the earth’s interior are inferred because How do earthquake waves tell us what’s in the earth? The seismic waves travel at different speeds and at different angles through each layer due to refraction The properties of the earth’s interior are inferred because We’ve never been past the crust

The Layers Continental Crust— Oceanic Crust— Crust—the outermost part of Earth just below the atmosphere or hydrosphere Continental Crust— thicker less dense mostly granite Oceanic Crust— thinner more dense composed of basalt

The Mantle Asthenosphere— Stiffer mantle— The layer below the crust- broken into 2 sections Asthenosphere— Plastic mantle Semi solid Silly putty like Stiffer mantle— Solid part Makes up 80% of earth’s mass

The Core Outer core- believed to be a liquid because S-waves do not travel through it Inner Core- believed to be a solid due to the extreme pressure

Page 10 of your ESRt’s Using this chart answer the ??’s on page 2 of your notes

What is the Theory of Continental Drift?

What is the Theory of Continental Drift? Alfred Wegner, 1915 The continents were once a super-continent called Pangea the continents are plowing through the ocean floors---most people didn’t believe this

What evidence supports this theory? Africa & South America look like they fit together similar fossils, rocks, and glacial striations

theory of Plate Tectonics theory of Continental drift? How is the theory of Plate Tectonics different than the theory of Continental drift?

What is the Theory of Plate Tectonics? Earth's crust is made up of plates that ride on top of the asthenosphere

What evidence supports this theory? distribution of earthquakes and volcanoes sea-floor spreading Marine fossils found on top of mountains What’s Mr. Parr got to say??

What makes the plates move? The plates move due to convection currents in the mantle video

Let’s contrast and compare Oceanic crust to Continental crust

How do oceanic and continental crust compare with regard to thickness and density? (look at pg 10 of ESRT’s) continental oceanic Density (ESRTs pg 10) thickness high low thin thick

Let’s learn more about these plates…

What are these types of plate boundaries? What are the key characteristics for each? Give an example of where each can be found.

trenches, volcanoes, subduction convergent boundary trenches, volcanoes, subduction Peru-Chile Trench

convergent boundary mountain building Himalayas

Two ocean crusts converging

transform fault slide past one another shallow earthquakes San Andreas Fault

divergent plate boundary new crust is made Mid-Atlantic Ridge

Rifting on land

Sea floor spreading

How was Hawaii formed??

Hot Spots Hot spots are found…… In the middle of plates If there is a weak spot in the lithosphere, magma will be able to come through- click here

Formation of Hawaii

What happens to the age of oceanic crust as distance increases from a ridge?

the iron minerals align with the magnetic poles (magnetic north) Explain how magnetic data can be used to show that oceanic crust is diverging at ridges. Use the diagram below to help explain your answer. the iron minerals align with the magnetic poles (magnetic north) same pattern on opposite sides of the ridge proves sea-floor spreading