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Earth Science Earth Science • Earth Science – Earth science is the study of planet Earth, including its structure, components, and essential characteristics. – Earth science fields of study are further classified according to specific topics, such as: • geography: study of Earth’s landforms, features, climates, and environment. • geology: study of Earth’s crust, including its composition and development. • meteorology: study of Earth’s atmosphere, including its composition and weather patterns. • oceanography: study of Earth’s water, including fresh and salt water. Earth Science • The multidisciplinary Earth sciences are generally classified according to one of four general spheres, or domains, of Earth: – lithosphere: the outermost layer of rocky land. – hydrosphere: the combined water (solid, liquid, and gas) found on and under the surface. – atmosphere: the enveloping layer of protective gas around the surface. – biosphere: the region that supports and nurtures life (includes portions of lithosphere, hydrosphere, and atmosphere). Earth Science • Geologic Calendar – Represents scientific understanding of age and history of Earth. – Primarily divided into two eons: Precambrian and Phanerozoic. Earth Science • PRECAMBRIAN: – Lasted from formation of Earth (about 4.6 billion years ago) to 570 million years ago. – Abundant life forms: algae, bacteria, fungi, worms, and sponges. Earth Science • PHANEROZOIC: • Lasted from 570 million years ago until the present. • Divided into three eras: – Paleozoic – Mesozoic – Cenozoic. The Three Eras of the PHANEROZOIC: • Paleozoic: – 570—245 million years ago – Lack of fossil preservation – Diversity of life relatively unknown The Three Eras of the PHANEROZOIC: • Mesozoic: – 245 - 66 million years ago – First mammals and flowering plants appear – Dinosaurs flourish The Three Eras of the PHANEROZOIC: • Cenozoic: – 66 million years ago until the present – Mammals diversified and ruled the surface of Earth – Primates first appeared The Lithosphere • Elements – – – – – – – – Collection of atoms of the same type. Simplest form of matter that: Cannot be formed from simpler substances. Cannot decompose into simpler substances. Organized on the Periodic Table of the Elements: Periodic Table contains 115 elements: 92 elements found naturally. 23 elements created artificially in laboratories. The Lithosphere • Minerals – Naturally occurring, inorganic, solid substances. – Formed when groups of atoms bond together. – Characterized by composition and arrangement of atoms. – Classified by physical properties (composition): – Crystal habit, hardness, color, cleavage, luster – Classified by composition and crystal structure (arrangement of atoms): – Native elements, silicates, carbonates, halides, oxides, sulfides, sulfates The Lithosphere • Rocks – Collections of minerals. – Classified into three natural types • igneous, • metamorphic • sedimentary – Distinguished by rock structure and mineral composition. The Lithosphere • IGNEOUS ROCK: – Forms as minerals from magma (hot, liquid rock) crystallize. – Originates deep inside Earth. – Is pushed to surface by magma. – Has a texture that is determined by its rate of cooling. The Lithosphere • METAMORPHIC ROCK: – Forms as a result of extreme pressure and/or temperature. – Can alter and change pre-existing, older rocks. – Can begin as either igneous or sedimentary rock. The Lithosphere • SEDIMENTARY ROCK: – Originates as detritus (loose sediment) formed from wind and water erosion. – Forms as detritus accumulates and compacts to a solid mass. Layers of the Earth • Layers of the Earth – Earth is generally divided into three regions: crust, mantle, core. – These layers are separated by density. Layers of the Earth • CRUST: – Acts as Earth’s hard Outer shell. – Divided into two parts by density: continental and oceanic. – Continental: • Located beneath surface— not covered with water • Approximately 30—40 km thick o much older than oceanic crust • Consists mostly of igneous rocks o composed mostly of granite and basalt – Oceanic: • Located beneath the oceans o approximately 6—11km thick • Composed mostly of basalt Layers of the Earth • MANTLE: – – – – – located under crust—is almost 3,000 km thick. contains nearly 80 percent of Earth’s total volume. is divided into inner and outer mantle. has temperatures ranging from 2,500°F—5,400°F heat from core travels through the mantle to the crust in circles called convection currents. – Convection currents are responsible for plate tectonics. Layers of the Earth • CORE: – – – – – – located approximately 3,000 km beneath surface. divided into inner and outer core. outer core composed of molten nickel-iron. inner core is solid because of intense pressure. temperatures reach 6,700°F. Outer core spins around inner core with rotation of Earth. – Earth’s magnetic field is generated by rotation of ions in molten core. Plate Tectonics • Plate Tectonics – Lithosphere broken into large, rigid plates. – major plates: African, North American, South American, Eurasian, Australian, Antarctic, Pacific – minor plates: Arabian, Nazca, Philippines – Seismic energy from two plates interacting with each other causes earthquakes. Intensity of earthquakes measured on the – Richter scale: • categorizes earthquakes on a numeric scale. • each increase in number represents a 30x increase in energy release. – Plates interact by colliding into, moving away from, and rubbing against each other. These interactions create earthquakes, volcanoes, mountain ranges. Plate Tectonics • CONVERGENT PLATE BOUNDARIES: – Occur when plates collide or move into each other. – Results include earthquakes, Andes and Himalayan mountains. Plate Tectonics • DIVERGENT PLATE BOUNDARIES: – Occur when plates move away from each other. – Results include oceanic ridges, East African rift valley, Rio Grande rift. Plate Tectonics • TRANSFORM PLATE BOUNDARIES: – Occur when two plates rub against, or move parallel to, each other. – Results include earthquakes along the San Andreas Fault. Plate Tectonics • Distribution of Earth’s land developed through movement of lithospheric plates. 250 million years ago All land is connected t-one super continent (Pangaea) 200 million years ago 100 million years ago Pangaea divides into northern Laurasia and southern Gondwanaland Laurasia and Gondwanaland break apart 50 million years ago continents closely resemble current distribution Geologic Processes • SURFACE-MODIFYING PROCESSES: – – – – – leave behind evidence of activity on Earth’s surface. are dynamic processes that continually change Earth. can be slow and steady (e.g., erosion, sediment transport). can be sudden and disastrous (e.g., earthquake, volcanoes). human activity can speed up, cause, or otherwise affect natural geologic processes: • farming and mining can speed up wind and water erosion. • deforestation can increase the occurrence of landslides and mudflows. • global warming and climate change can both lead: – directly to rising temperatures, melting glaciers, and rising sea levels. – indirectly to floods, earthquakes, hurricanes, and increased volcanism. SURFACE-MODIFYING PROCESSES: • Tectonism – fracture and deformation of Earth’s crust • Volcanism – molten rock reaches surface – basaltic lava flows (fluid eruptions of molten rock) – pyroclastic flows (eruptions of solid debris such as rock and ash) • Water-modifying / fluvial force – water erosion – sediment transport – sandbar formation SURFACE-MODIFYING PROCESSES: • Aeolian process – – – – wind erosion rock carving and shaping sand dune formation sediment transport • Glacial process – landscape leveling – sediment and rock transport – creation of fjords, crevasses, cliffs, rock formations • Gravitational processes – landslides, mudflows, avalanches