HAND-OUT-2ND-QUARTER.doc - EARTH SCIENCE \u2013 CHAPTER III Layers of the Earth Crust the thin outermost layer of the earth it makes up only one percent of

HAND-OUT-2ND-QUARTER.doc - EARTH SCIENCE u2013 CHAPTER III...

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EARTH SCIENCE – CHAPTER III Layers of the Earth Crust the thin, outermost layer of the earth it makes up only one percent of the earth's mass Continental Crust 35-70km thick Oceanic Crust 5-10km thick Crust Continental Crust Averages 35 to 70 km thick (70 in mountainous areas) It is composed primarily of granitic or granite rocks. Oceanic Crust Averages 5 to 10 km thick It is composed primarily of basaltic or basalt rocks. Crust Separating the crust and the Earth’s second layer is called the Mohorovicic Discontinuity or MOHO. Named after Andrija Mohorovicic Mantle More than 82% of the Earth’s volume is contained in the mantle. A solid rocky shell that extends to a depth of 2,900km. The dominant rock type in the uppermost mantle is the peridotite. Asthenosphere A stiff layer named asthenosphere lies beneath the lower crust and the upper mantle. The top portion of this layer has a temperature- pressure regime that results in a small amount of melting. Mantle A boundary called Gutenberg Discontinuity separates the Mantle and the Earth’s third layer. This is named after Beno Gutenberg, a German seismologist. Core It makes up nearly one third the mass of the earth Inner core 1,250km thick solid iron and nickel Outer core 2,200km thick liquid iron and nickel Core Primary Waves (P-waves) compressional waves longitudinal in nature Back-and-forth movement of rocks Secondary Waves S-waves shear waves transverse in nature sideways movement of the rocks. Why does Earth have a magnetic field? Earth’s core is iron, a magnetic material Earth’s outer core is liquid iron When this liquid iron circulates around the core, a magnetic field is developed Continental Drift Theory A glimpse of the past Development of the Continental Drift Theory As a young scientist, Wegener was curious about Earth’s continents. In 1910, Wegener formed a hypothesis which stated that 250 million years ago, all the continents were once joined together in a giant landmass. He named this landmass PANGAEA. This giant supercontinent was surrounded by a single giant sea known as the Panthalassa. According to Wegener, Pangaea split up into smaller continents. Laurasia and Gondwanaland Theory of Continental Drift, which states that parts of the Earth's crust slowly drift atop a liquid core. The giant landmass, Pangaea, drifted apart and formed the seven known continents today. Evidence to Support the CDT Sources of Evidences for the Continental Drift Theory Wegener used 3 types of evidence to prove his theory. Evidence from landforms Evidence from fossils Evidence from climate Evidence from Landforms or The Continental Jigsaw The shapes of the continents seemed to fit together. Mountain ranges and other features also lined up.

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