EESA06H3 Study Guide - Midterm Guide: Continental Crust, Oceanic Crust, Sedimentary Rock
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Lecture 1(Earth Systems):Biosphere: the living and dead organisms.Hydrosphere: Earths liquid and solid water (cryosphere).
Atmosphere: Mixture of gasses (78% nitrogen and 21% oxygen).Lithosphere: The upper part of the solid earth.Ecosphere: when all the
spheres interact with the biosphere. Components of Earth:Compositional Layers: Crust, Mantle, Core.Physical Layers:Lithosphere (solid,
rigid), Asthenosphere (solid, weak), Mesosphere (solid), Liquid outer core, solid inner core.Seismic Waves: P-waves (travel through liquids
and solids) and S-waves (cannot travel through liquids). Crust:Oceanic (earthquakes are faster) and continental crust (thicker).Good and
Bad Science:Good Science:1. Scientific explanations are tentative and can and do change (Changes occur, example Pluto). 2. Scientific
explanations should be predictable and testable (example is weather). 3. Scientific explanations are based on observations or experiments and
are reproducible. (Glaciers going back to them)4. A valid scientific hypotheses offer a well-defined natural cause o mechanism to explain a
natural event. (Hypothesis is backed up like the ozone layer and atmosphere)Bad Science:1.An attack on scientist, not science (scientists
fabricating data to support their hypotheses). 2. People who argue from authority (being powerful does not make him or her right). 3. Confusion
over cause and effect (it happened after, so it was caused by, example lucky shirt). 4. The use of bad statistics (bad data collection or biased
survey or response).
Lecture 2(Plate Tectonics):False theories are the Contracting and Expanding earth.Isostasy:a general equilibrium of the forces tending to
elevate or depress the earth's crust. Alfred Wegener:1. he felt that continents drifted around the surface of the earth. 2. Displacement across
the Atlantic Ocean happened in geologic time (jigsaw puzzle). 3. Continents are still moving (Pacific closing ocean is old, deep, more mafic
and Atlantic is spreading, young and shallower). Supercontinent Pangea: made of Laurasia (North America and Europe) and Gondwana (The
rest south). Mid-ocean Ridges: upwelling or divergence and have high heat flow (only have shallow earthquakes). Trenches: down welling or
convergence.Sea floor spreading (Harold Hess): New crust forms in the middle of mid oceanic ridges and the old gets recycled in the
trenches which feed it back into the mantle where it is melted.Jack Tuzo Wilson:Hot Spots:volcanoes forming above hot mantle upwelling
(stationary mantle plumes that burn through the lithosphere, example is Hawaiian Islands).Plate Tectonics:Earth is divided into mechanical
layers; outer layer is rigid lithosphere which floats atop plastic asthenosphere.3 types of Boundaries:Convergent: Two plates move toward
one another. A typical result is that one plate slides under the other.(Ocean and continent produce dangerous volcanoes called volcanic arcs.
Ocean and Ocean have normal volcanoes like in Hawaii so volcanic islands. Continent and continent (obduction) produce huge mountain
ridges).Divergent:two plates move apart relative to one another, in most cases magma fill the space between the plates.Transform:two plates
move horizontally past one another (San Andreas Fault).
Lecture 3(Minerals and Igneous Rocks):Main Minerals: Quartz: Sillicates, Tectosillicates, common in all types of rocks.
Feldspars: Sillicates, Tectosillicates, common in all types of rocks. Mica’s: Sillicates, phyllosillicates, common in igneous and metamorphic
rocks. Calcite: Carbonates, common in sedimentary rocks. How to identify Minerals:Color, Streak (silicates do not streak), Hardness, and
Igneous Rocks:Source: Magma, Process: Freezes, Product: igneous rocks.2 Lava: A’a: is blocky lava, from cooler flows. Pahoehoe: is
ropy lava, from hotter flows.2 Cooling Processes: Intrusive (cool underground, cool slowly and form coarse crystals) andExtrusive (cool at
the earth’s surface, cools quickly and form fine crystals).Dyke: Cut across layers of rock. Sils: follow same way horizontally. Batholith: large
mass of intrusive igneous rock believed to have solidified deep within the earth. Volcanic Pipe: allows flow of magma up to the top of the
volcano. Igneous Rocks are classified by composition:Mafic (rich in magnesium and iron) or Felsic (rich in silica and light things). Igneous
Rock Examples:Felsic Rocks (continental crust):Ryholite(fine grain)and Granite (coarse grain). Intermediate Rocks: Andesite
(fine grain) and Diorite (coarse grain). Mafic Rocks (oceanic crust): Basalt (fine grain) and Gabbro (coarse grain).Shield
Volcanoes/Hot Spots:hill shape, made of mafic, basaltic rock and magma, not explosive or dangerous (example is Mauna Kea/Mauna Loa
or Hawaii islands). Composite/Stratovolcano/Subduction zones: Cone shape, made of lava and broken rocks, magma is felsic or
intermediate and highly dangerous (example is Mt Rainier/Mt St Helens).Composition Density:Oceanic crust is mafic and is denser than
continental crust which is felsic and light.Composition Viscosity: Felsic magma is sticky and has high viscosity, speed flow is slow and
covers small areas but is very explosive, and Mafic Magmahas low viscosity and is flows fast and covers a lot of ground but it is not
explosive.Ridge Push: where divergent boundaries are. Slab Pull: where trenches are at subduction zones.
Lecture 4(Sedimentary and Metamorphic Rocks):Sedimentary Rocks:Source: Sediments, Process: deposited, precipitated,
compacted and cemented with silica, Product: Sedimentary rocks. Lithification: sediments compact under pressure, lose fluids and gradually
turn into stone.Environments of deposition of sedimentary rocks:Marine environments: reefs, submarine fan/canyon, shelf, flood plain.
Continental environments: beach, sand dunes, glaciers, alluvial fans.Chemical/Biological Sedimentary Rocks:are precipitated from sea
water or made by coral reefs and animal shells.Clastic Sedimentary Rocks: broken bits of other rocks, Clastic sedimentary rocks made of
deposited particles of sand, slit and gravel. Clastic Sediments are moved by water, wind and glaciers.Named by size: Clay, silt, sand,
pebbles, cobbles, and boulders.Also named by Grainsize:mudstone/shale, sandstone, conglomerate.Sediment transportation:longer
sediments are transported, become more round and smooth because they rub against each other.Clastic Sedimentary Rock
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