EAR 105 1st Edition Lecture 3Outline of Last Lecture I. Introduction to Earth ScienceII. Origin of the EarthIII. Constituency of the EarthOutline of Current Lecture IV. Constituency of the Earth—continueda. By compositionb. By behavior (rheology)V. Plate TectonicsVI. Continents & Ocean BasinsCurrent LectureIV. Constituency of the Earth—continued- There are two ways to categorize the Earth’s layers: by composition and by behaviora. Composition: Crust, Mantle, Coreo Crust: two types of crust are continental and oceanicContinental Crust Oceanic CrustThickness: 30-40 km; max 70 km 5 km (very thin!)Composition: Silica-rich less dense Iron-rich more denseRock: Granite Basalto Mantle: Solid, rocky shell- More than 82% of Earth’s volume- 2850 km thick- Made of iron, magnesium, oxygen and silicon- Separated into upper and lower mantleo Core: Innermost layer of Earth’s composition- 3450 km thick (but less surface area than surrounding mantle)- Made of iron-nickel alloyb. Behavior (Rheology): Lithosphere, Asthenosphere, Mesosphere, Outer Core, Inner CoreThese 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.o Lithosphere: rocky outer shell- contains crust & uppermost mantle- 100 km thick- Solid—makes the plates in plate tectonicso Asthenosphere: Weak inner shell- Contains some mantle- Flows like taffy—causes lithospheric plates to shifo Mesosphere: Layer underlying Asthenosphere—lower mantle - Hot, but solid and rigid due to overlying pressureo Outer Core: Hotter- Liquido Inner Core: Even hotter- Solid due to immense pressure from all other layersV. Plate Tectonics Theory - The lithosphere is divided into slabs, which are in gradual but constant motion.- None of these slabs directly corresponds to the margins of the continents.- Three types of plate boundaries: Convergent, Divergent, Transformo Convergent: plates move together- Results in the subduction (sinking) of more dense oceanic crust- Mountain building- Volcanoeso Divergent: plates pull apart- Results in oceanic ridges, rifs, islands- Volcanoes o Transform: plates move past each other- Results in faults and earthquakes- Not associated with volcanoes or mountain buildingVI. Continents and Ocean Basins- Major Features of Continents:o Mountain Belts: occur in clusters along margins of continents ex. circum-Pacific belt forms West Americas’ mountains and Japan, Aleutians, and Philippines’ volcanic islandso Stable Interior: self-explanatory—the stable inside-region of continents Shields: expansive, flat regions made of deformed crystalline rock Platforms: expansive, flat regions made of deformed sedimentary rock- Major Features of Ocean Basins:o Continental Margins: seafloor attached to major landmasses Contains continental shelf, slope, and riseo Deep-Ocean Basins: between continental margins and oceanic ridges Abyssal Plains: very flat plains in ocean Deep-ocean Trenches: extremely deep depressions max 11,000+ meters deep. Narrow, relatively rare Seamounts: submerged volcanic structureso Oceanic Ridges: Most prominent feature on ocean floor; broad, elevated belt of layers of igneous rock that winds around the