ASTR 151 1st Edition Lecture 13 Outline of Last LectureI. Chapter 7 Structure of EarthII. Chapter 7 Atmosphere of EarthOutline of Current LectureIII. Chapter 7 Section 1 Structure of Earth ContinuedIV. Chapter 7 Section 3 Earth`s InteriorV. Chapter 7 Section 4 Surface ActivityCurrent LectureI. Chapter 7 Section 1 Continueda. Body Wavesi. Travels through the interior of the crustii. Gets refracted depending on the densityb. Surface Wavesi. Slower than body wavesii. Travels across the surfacec. Shear Wavesi. Produced by earthquakes sometimesii. Also called “pressured waves”II. Chapter 7 Section 3 Earth`s Interiora. We use patterns of reflections during earthquakes to deduce interior of the Earth1. Mantle is less dense than core (80% of the Earth)2. Core is metallic3. Outer core is liquid/ inner core is solid due to pressureii. Radioactivity provides heat1. Radioactivity DecayThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.2. Radioactive Dating3. Half Lives – after one half of life is expended, decay beginsiii. Earth may have been molten when it was formed and remelted due to bombardment by space debris 1. Heavier materials sank to the center b. Carbon Datingi. When plants or animals die they equal 14^C: it decays due to radioactivity1. The ratio of 12^C to 14^C changes over time, that’s what you measure and compare to atmosphere2. Not useful for things older than 60,000 years old, not enough 14^Cii. To measure much older things, you need longer half-livesiii. Continental Drift1. Earth`s surface is covered with crustal plates, which can move independently2. Plate Boundariesa. Collisions – two plates crunchb. Subduction – one plate goes under other3. Tectonics = Pangea meaning “all lands”III. Chapter 7 Section 4 Surface Activitya. Ring of Firei. Circum-Pacific seismic belt1. 90% earthquakesb. Shearingi. Plates move on each other causing faultsc. Riftsi. Plates move away from each otherd. Plates are moved by
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