OSU OC 103 - e-OC103_Lesson07-08 (13 pages)

Previewing pages 1, 2, 3, 4 of 13 page document View the full content.
View Full Document

e-OC103_Lesson07-08



Previewing pages 1, 2, 3, 4 of actual document.

View the full content.
View Full Document
View Full Document

e-OC103_Lesson07-08

11 views


Pages:
13
School:
Oregon State University
Course:
Oc 103 - Exploring The Deep: Geography Of The World's Oceans

Unformatted text preview:

OC103 Lessons 7 8 The Creation Aging and Recycling of Ocean Floor The Shifting Crust How it Works Last time we introduced the concept of Plate Tectonics and how new oceanic crust is created at seafloor spreading centers then slides across Earth s surface and subducts back into the mantle at subduction zones This double lesson will illustrate how that happens and why it is important for the oceans Components of the Plate Tectonic Conveyor Belt When Harry Hess proposed that the oceanic crust acts as a conveyor belt that carries continents with it he probably had in mind something like the figure below As the tectonic plates pull apart at seafloor spreading centers magma hot molten rock called lava when it reaches the surface rises into the crack from below and the magma solidifies into new oceanic crust The process repeats when the new crust later splits and more magma rises from below As this process continues over millions of years entire ocean basins floored by oceanic crust are formed Lithosphere and Asthenosphere You will notice in the figure on the previous slide the use of the terms lithosphere and asthenosphere It turns out that the plates that move around on Earth s surface are made of not just the crust but also the uppermost part of the mantle that is a little cooler and harder than the mantle just below it so it is strong enough to behave as part of the plates see figure below The cold and strong outer layer that includes the crust and uppermost part of the mantle is called the lithosphere from the Greek for stone which is what tectonic plates are made of The lithosphere can be brittle or elastic that is it can bend to a certain extent but will break if bent too far or too fast Below the lithospheric plates the mantle is solid but hot and weak and is called asthenosphere from the Greek for weak The asthenosphere is hard but plastic and deformable picture cold peanut butter or honey so plates can move slowly across it by deforming it Below the asthenosphere



View Full Document

Access the best Study Guides, Lecture Notes and Practice Exams

Loading Unlocking...
Login

Join to view e-OC103_Lesson07-08 and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view e-OC103_Lesson07-08 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?