EES 1030 1st Edition Lecture 14 Intro to Earth ScienceOceans and ContinentsMapping the Ocean floor:We know more about the surface of the Moon than we do about the ocean floor.Multibeam sonar: map bathymetry over the 10-20 km swath to 1 m. slow. Satellite pictures: 1990’s. seamounts > 1000 m high.Features of the ocean floor- about 50% were previously uncharted.Passive Continental Margin: area that transitions between oceanic and continental crust.Continental shelf and slope. Doesn’t have many earthquakes and is stable.Active continental margin: area where the oceanic crust is recycled under the continental crust. Has deep-ocean with trenchesContinental platform: stable interior of continent. Low elevation and relatively flat. Continental shield: areas covered by relatively horizontal undeformed rocks. Dome: anticlinal structure. Oldest rocks in center.Basin: synclinal structure. Youngest rocks in center.Mountain Belts:- Young- American Cordillera, Alps, Himalayas- Older- Appalachians, UralsMountain Building:- Occurs at mostly convergent plate boundaries.- Continent to continent- Continent to Ocean.Convergent Margins- most intense area of active magmatism above sea level at the present time. Most volcanic activity.Subduction zone: where the oceanic crust is subducted into the mantle under the continental crust. This occurs with continent to ocean boundaries.*Collisions occur with continent to continent boundaries.Isostasy: gravitational equilibrium between earth’s crust and mantle. Glacial Rebound: rise of land masses that were depressed by the huge weight of ice sheets. Terrance: crustal fragments whose geologic history is distinct from that of the adjoining
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