Exam 1 cheat sheet

Week 1 Hydrosphere: Earth is the Blue Planet, it is covered by water (71%) to an average depth of 3800 meter Earthquakes, landslides, floods, volcanic eruptions, tornadoes, hurricane natural disasters cost the United States over $17 billion each year and the costs are still increasing yearly. • The World Bank reported that direct economic losses from natural disasters have totaled to 3.8 trillion since 1980 and multiplied five fold in the past two decades. – Physical geology • Materials and processes which compose and operate on the surface of, and within, Earth; Historical geology • Origin and evolution of Earth's continents, oceans, atmosphere, and life Greenhouse effect and climate change – Recycling of carbon dioxide between Earth’s crust and atmosphere – Degree which human activity contributes to greenhouse warming 4 layers physical property: • Lithosphere – Solid upper mantle and crust; broken into plates • Asthenosphere – Surrounds lower mantle; flows slowly • Lower Mantle next is core Three concentric layers based on chemical property Density differences – Core • Highest density • 16% of Earth’s volume • Iron and nickel – Mantle • 83% of Earth’s volume • Peridotite – Crust • Continental crust: silicon and aluminum • Oceanic crust: basalt, gabbro Igneous rocks – Result when magma or lava crystallizes • Intrusive or extrusive • Sedimentary rocks – Composed of sediment from: • Rock/mineral fragments • Precipitation of minerals from solution • Compaction of plant and animal remains : Metamorphic rocks – Form from alteration of other rocks, usually by: • Heat • Pressure • Chemically active fluids :::: Hydraulic system distributes water Week 2 12 inches in a foot, 3 feet in a yard, 5,280 feet in a mile, 16 ounces in a pound, 4 quarts to a gallon All landmasses were originally united into a supercontinent named Pangaea • Consisted of a northern landmass called Laurasia, and a southern landmass called Gondwanaland - Evidence The similarity of rock sequences and mountain ranges- Glacial evidence– Glacial striations (scratch marks) near the present-day equator indicate that continents Earth's Convection Cells : loop red and blue cycle each other have moved Fossil evidence Most compelling evidence, Permian-age coal deposits on all Gondwana continents, Mesosaurus found only in Brazil and South Africa Alfred Wegener was a German scientist who proposed the idea of continental drift in 1912. Earth’s present magnetic field is "normal” – North and south magnetic poles located approximately at the north and south geographic poles– At various times in the geologic past, Earth’s magnetic field has completely reversed • The magnetic south pole near the geographic north pole and the magnetic north pole near the geographic south pole Seafloor spreading – Continents and oceanic crust move together – Thermal convection cells in the mantle Oceanic crust youngest at the mid- ocean ridges Hot spot – Location on Earth’s surface where a stationary column of magma has formed a volcano – Hawaiian island chain Divergent boundaries occur where: – Plates are separating – New oceanic lithosphere is forming – Crust is extended, thinned, and fragmented as magma ::: Convergent boundaries: where two plates collide – Three types of convergent boundaries: • An oceanic-oceanic boundary: two oceanic plates collide; one ocean plate will subduct beneath the margin of the other plate • An oceanic-continental boundary: an oceanic plate and a continental plate collide; the oceanic plate will subduct (oceanic plate denser) • A continental-continental boundary: two continents collide; no subduction of continents (mountain) Transform boundaries – Plates slide laterally past each other along transform faults – Change one type of motion between plates into another type of motion – Example: San Andreas Fault •Paleomagnetism: The magnetic minerals in molten rock align with earths magnetic field Week 3 earthquakes Focus – point where an earthquake’s energy is first released – Epicenter – that point on the surface vertically above the focus , the Relationship between plate boundaries and earthquakes – Foci at divergent and transform boundaries typically shallow – Foci at convergent boundaries are deeper About 80% of all earthquakes occur in the circum-Pacific belt • 15% within the Mediterranean-Asiatic belt • 5% occur largely along oceanic spreading ridges or within plate interiors – More than 900,000 earthquakes occur per year – More than 31,000 are strong enough to be felt Seismic waves cause most of the shaking during an earthquake – P-waves , primary waves • Compressional • Can travel through solids, liquids, and gases • Fastest – S-waves , secondary waves • Shear waves • Travel only through solids. Surface waves – Rayleigh waves • Slower • Behave like water waves – move material vertically – Love waves • Similar to S-waves • Move material horizontally About 550 volcanoes have been active in historical times – 10 to 20 at a time •Not all volcanism involves volcanoes Magma is composed of molten rock and is stored in the Earth’s crust. Lava is magma that reaches the surface of our planet through a volcano vent. Factors affecting Viscosity – Temperature - hotter magma is less viscous (more fluid). Basaltic (mafic) magmas hotter than Granitic (felsics) – Composition (Silica content)• Felsic lava (e.g. rhyolite) is most viscous due to high silica content • Intermediate lavas (e.g. andesite) viscous. • mafic lava (basalt) has lower viscosity - more fluid-like due to lower silica content Gases constitute only a small portion of magmas • Primarily water vapor • Lesser amounts of carbon dioxide, nitrogen, sulfur dioxide, and hydrogen sulfide– Most volcanic gases dissipate without harm to humans Large amounts of gas and a high viscosity (sticky) magma will form an explosive eruption! Ash fall– Pyroclastic flow– Pyroclastic surge mall amounts of gas and (or) low viscosity (runny) magma will form an effusive eruption (erupt from the ground)