Earth's Interior Review Lec 3 PDF
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Uploaded by SereneShark
Oklahoma State University
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Summary
This document reviews the structure of Earth's interior, focusing on seismic waves, mechanical layers, and the creation of the Earth's magnetic field. It provides a concise study guide.
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Week 1 -‐‑ Lecture 3 STUDY GUIDE Structure of the Earth Slide 4 & 5 – Know the 2...
Week 1 -‐‑ Lecture 3 STUDY GUIDE Structure of the Earth Slide 4 & 5 – Know the 2 types of seismic waves – P and S waves P waves (primary/compressional waves): travel through solids and liquids S waves (secondary/shear waves): travel only through solids These relationships helped geologists know that the Outer Core is liquid because S waves do not travel through a liquid. (Slide 29) Slide 6 -‐‑ 8 – Discontinuity = a boundary between 2 dissimilar materials that cause points of reflection or points of refraction at contact between distinct layers. This means the interior of the Earth is layered and is NOT Homogeneous Slide 10 (& 17-‐‑ 21) – Know the names of the mechanical layers within the Earth. Be able to list them in order from the surface inward to the center of the Earth. Lithosphere – outermost rigid layer Asthenosphere -‐‑ Upper Mantle -‐‑ relatively week layer, may be partially melted Mesosphere (Lower Mantle) – layer between Asthenosphere and Core Outer Core – liquid metallic layer having convective flow Inner Core – solid metallic sphere Slide 23-‐‑24: Know: the Moho is the boundary between the Lithosphere and the Asthenosphere located 660 km below the surface. It is due to mineral change due to high pressure at depth. Slide 25 & 28 – P-‐‑waves reflect and refract at the Lower Mantle-‐‑Outer Core boundary Go through both the Outer(liquid) and Inner Core (solid) Slide 29 – S-‐‑waves reflect off the mantle-‐‑core boundary (broad shadow zone) Do NOT go through the liquid Outer Core. Slide 30 – The Mesosphere (lower Mantle) extends from the Moho at 660km to the Outer Liquid Core. S-‐‑waves stop at his contact, while P-‐‑waves refract but continue through the Outer Core and Inner Core. Slide 31 & 32 -‐‑ The Mantle-‐‑Outer Core boundary is referred to as the D’’ (D Double Prime Layer). The circulation in the liquid outer core is transferred into circulation in the Lower and Upper Mantle. This circulation in turn drives the plate movements of the Lithosphere at the surface. Slide 33 -‐‑ The contact between the liquid Outer Core and the solid Inner Core boundary is called the Lehmann Discontinuity. As P waves enter the solid inner core, they speed up Slides 34 – 36 – The source for the Earth’s heat: radioactive decay primordial heat released when the Iron Inner Core crystallized primordial heat generated from formation of the Earth Slide 39 & 40 – Convection circulation in the liquid outer core acts as a self-‐‑sustaining dynamo creating the Earth’s magnetic field Slide 42 -‐‑ The Earth’s magnetic field protects the Earth’s surface from the electromagnetic energy from the Sun. (solar flares and solar radiation) The Earth’s magnetic field has reversed polarity in the past.
