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| A theory to explain global distribution of volcanoes, earthquakes, faluts, mountain belts, features of seafloor, evolution of continents and oceans. sea floor spreading |
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| A U.S. Navy Ltnt., created a bathymetric map with a large conttinuous mountain chain in the middle of the Atlantic Ocean. |
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| How was Matthew Maury's findings confirmed? |
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| by Trans-Atlantic telegraph able and WWI echo soundings. |
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| (1831-1914) expert on the geography of Alps, theorized alps to the north were once at the bottom of an ocean, fern was found in fossils in s. america, africa and india. |
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| What did Eduard Suess propose? |
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| Super continent "Gondwanaland" .. a land bridge connecting all the continents. |
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| (1880-1930)- cataloged fossils as a graduate student, similarites intrigued him, developed ideas while recovering from wound received in WWI. |
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| Who proposed continental drift hypothesis? |
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| In what year did Wegener propose continental drift hypothesis? |
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| What was the supercontinent hypothesis? |
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| Supercontinent called pangea began breaking apart about 200 MYA. |
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| What was WEgener's Evidence? |
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| Fit of the continents, rock type of structural similarities and fossil evidence on different continents, paleoclimatic evidence (bones of same animals found on different continents of where they would connect. |
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| Was WEgener's hypothesis embraced? |
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| What was discovered on U.S.S. Atlantis? |
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| 1947 - Sediments of the AO are much thinner than originally thought. 1950s - use of magnetometers revealed odd magnetic variations on the ocean floor - led to magnetic polarity in rocks. |
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| Detects iron or magnetic objects, allows ships to find submarines before submarine finds them, strange readings reported (difference in height) of the floor of ocean. |
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| What is the earth's magnetic field? |
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Definition
| resembles that produced by a large bar magnet, magnetic field lines wrap around earth, magnetic north is not equal to true north (true north as on a compass). |
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| Is magnetic north, true north? |
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| Sudy of magnetic field properties of rocks. |
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| Describe paleomagnetism in earth/rocks |
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| Magnetic field of eart his imprinted upon iron-bearing rocks when they form. |
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| What does paleomagnetism help in studying |
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| Provides a record of magnetic reversals and original latitude. |
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| Drift of the magnetic field by the drift of the continent. |
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| Princeton professof geology and navy reservist |
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| What was Hess' contribution? |
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| He was called to serve in WW II, got command of his own ship, got echo sounder, magnetometer, kept instruments running 24/7. |
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| What did Hess and his crew do? |
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| Conducted echo sounding surveys in teh Pacific, measured the oceans to the deepest points (7 miles), discovered 100s of flat-topped mountains on the Pacific floor - GUYOTS) |
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| They are flat-topped mountains on the Pacific floor. |
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| What evidence do we have for sea floor spreading? |
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| Earthquakes at ridges and subduction zones. |
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| Where is heat flow highest in ocean floor? |
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| AT ridges, decreases away from ridges. |
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| How old is the oldest crust rock on sea floor |
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| Are sediments older or newer away from the ridges? |
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| Earths magnetic field reverses |
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| Yes.. this change is recorded by iron minerls in rocks. |
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| Where is new crust formed and old crust consumed |
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| Formed at ridges, consumed at trenches. |
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| Describe Hess' sea flor spreading hypothesis |
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Definition
| New crus forms at ridges, old crust consumed at trenches, theory of sea floor spreading driven by convection cells. Oldest crust at the trench, newest crust at the ridge. This being done by the activity of the convection cell (magma in the mantle). |
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| Based on radiometric dating, how old is the oldest crustal rock |
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| Are sediments older close to the ridge or away from the ridge? |
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| What three things make up the theory of plate tectonics? |
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| Continental Drift + Sea floor spreading + Paleomagnetism = plate tectonics. |
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| Is the earth's lithosphere, one solid plate? |
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| No. It is broken up into plates. |
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| What causes the plates to move? |
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| Hot, weak asthenosphere allows them to move. |
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| The outer layer of earth's structure including the crust and the upper mantle to a depth of about 200 km. |
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| What are the major components involved in plate tectonic movements? |
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| A plastic layer in the upper mantle 80-200 KM deep that may allow lateral movement of lithospheric plates and isostatic adjustments. |
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| What is the rate of movement of plates? |
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| What are the three layers of earth composition? |
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| What are the earths physical property layers |
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| Lithosphere, Asthenosphere, Mesosphere, Outer Core, Inner Core |
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| What is the average rock density of continental crust? |
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Definition
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| what is the composition of the crust? |
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| What is the density of the oceanic crust? |
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| What is the composition of the oceanic crust? |
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| Is the color of the rock produced by the earth's magnetic field dark or light color? |
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| 82% of earth's volume, solid rocky layer, upper portion has peridotite, TWO PARTS, mesosphere (lower mantle) and asthenosphere, upper mantle. |
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| What are the two parts of the mantle? |
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| Mesosphere (lower mantle), asthenosphere (upper mantle). |
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| Larger than the planet Mars, mostly iron and nickel, two parts, outer core, liquid, inner cole, solid. |
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| What is the average density of the core? |
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Definition
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| What are the two parts of the core? |
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| Outer core, liquid, inner core, solid |
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| What is responsible for the earth's magnetic field? |
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| the core, made of material that conducts electricity. Core is mobile. |
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| Is the core mobile or fixed? |
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| Yes. 3,950 Kelvin (6,650F/3,677C) |
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| In magnetic reversals, by what is the earths' magnetic field sustained |
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| Geodynamo generates new magnetic fields. |
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| What happens when the fields in the magnetic field do not line up? |
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| What happens if the unstable area grows large enough? |
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| Where is there an area now getting big enough to cause a filp? |
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| east-central atlantic ocean. |
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| How long do flips take to complete |
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| Wave that travels through liquids and solids. |
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| P-waves travel faster than S-waves |
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| What is the direction of a P-wave |
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| What is the direction of an S-wave |
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| S-wave travels through liquids |
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| Describe seismic waves as they pass from one material to another |
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| The balancing of pressures exerted by mass of continents and ocean crust on mantle (think of my mattress). |
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| Because of Isostacy, continents float on mantle like iceergs in water |
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| Continental crust is heavy |
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| Where to major interactions among individual plates occur? |
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| Describe the three type of plate boundaries |
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Definition
| Divergent, Convergent and Transform fault. |
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| What is the movement of divergant plate? |
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Definition
| They spread apart. (Mid-Atlantic Ridge). |
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| What is the movement of convergent plate? |
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Definition
| Come together. (Andes Mountains, Cascade Mts.) |
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| What is the transform fault movement? |
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Definition
| Pass along each other. (San Andreas Fault, Alpine Fault). |
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| A mid-ocean ridge is called a continental rift on land |
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Definition
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| Where are divergant plate boundaries mostly located? |
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Definition
| along the axis and midoceanic ridges and a few on land (continental rifts) |
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| A trench offests a fracture zone |
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Definition
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| Dead sea fault is transofrm fault |
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| What is extensional tectonics? |
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| Land is extending - rio grande valley rift is composed of basalt. |
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| Basin and Range, region is slowly pulling apart, no active spreading center. |
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| Trenches are surface expression of subduction zone |
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Definition
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| What are convergant plate boundaries? |
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Definition
| Where two plates collide. |
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| What three types of convergant plates are there? |
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| Oceanic-continental. Oceanic-oceanic and Continental-continental. |
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| Give an example of Ocean-Continent convergence |
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| Describe ocean-continent convergence |
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| Subduction zone, ocean crust is 3 gm dense, continental crust is 2.7 gm dens. Ocean crust gets subducted, melts, then melt rises up. Big explosive volcanos are ocean-continent convergence. (Andes Mts. and Cascade Mts.) |
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| Describe ocean-ocean convergence |
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| Two oceanic plates. The older and colder plate gets subducted beneath the younger plate, results in island arc, result in subduction. (Mariana and Aleutian Islands) |
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| Japan has five arcs colliding |
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| Describe continent-continent convergence |
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| Come together as huge collision. Himalays formed by india pushing into Asia. (HImalays and Alps). |
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| DEscribe transform fault boundaries |
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| Plates slide past each other, no new lithosphere is created or destroyed, most join two segments of midocean ridge as part of prominent linear breaks in the oceanic crust known as frzcture zone. |
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| California is on what plate? |
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| California is at plate boundary. |
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Definition
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| Describe the two types of transform faults |
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| Oceanic - wholly in ocean floor. and Cotinental -extends from mid ocean ridge across the continent. |
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| Areas of intense volcanic activity that remain in more or less the same location over long periods of time and are unrelated to plate boundaries. |
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| Hot spots are unrelated to plate boundaries |
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| The majority of world's hot spots are not related to plate boundaries, those that are are along divergant plate boundaires where the lithosphere is thin |
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| How are hot spots formed? |
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| Caused by rising plumes of mantle material. |
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| False. They are stationary |
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| The Hawaiian islands are a result of a hot spot? |
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| An island that is below water surface. |
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| An island that with erosion has had the top part flattened. |
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| Seamount and Tablemount are related to hot spot |
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| Coral reefs associated wtih subsiding seafloor |
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| Describe the three types of coral reef? |
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| What was the convergent boundary largest earthquake? |
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