{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Lecture 4 - LECTURE NOTES GEOSCIENCES 40(Marone/Arthur Sep...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
LECTURE NOTES -- GEOSCIENCES 40 (Marone/Arthur) Sep 8 2005, Lecture 4 Sea Floor Spreading Earth's surface is in motion! Recall: THE "WILSON CYCLE" (CREATION AND DESTRUCTION OF OCEAN BASIN) SUPPORT FOR SEA FLOOR SPREADING -Magnetic "stripes" on seafloor What Is Driving All This Commotion? Heat flow from within the Earth drives plate motions Plates are the brittle layer (~ 100 km thick) that is carried on more ductile region below (asthenosphere) Motion is driven by heat flow out of Earth Earth's interior is VERY HOT! Mantle Convection internal heat engine radioactive decay Three main forces that move plates 1. Ridge Push 2. Basal drag 3. Trench Pull EARTH'S MAGNETIC FIELD The Dipole Field (see diagram) -A giant bar (dipole) magnet along spin axis -Magnetic "force" lines (Today "Normal") --"enter" at North Pole parallel to spin axis --"exit" at South Pole parallel to spin axis --force line angle w/ surface of earth progressively horizontal towards equator -Many rocks record orientation of ancient magnetic field (polarity or paleolatitude) Polarity Reversals -Earth's field orientation flips periodically (N magnetic pole and S magnetic pole switch); -Related to circulation of molten outer core
Image of page 1

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern