OceanFloor - No photosynthesis possible (too deep), so...

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Chapter 13 Divergent Boundaries: Origin and Evolution of the Ocean Floor Note: The “divergent boundary” part was largely covered in Chapter 2, so we won’t be spending much time on that here. The focus will be the Ocean Floor. Methods of ocean exploration Pre-1940s: drop anchor and measure rope! Sonar Multi-beam sonar Seismic surveys Air gun Radar (satellites) Edge of continent/beginning of ocean is not the shoreline. Is instead the edge of the continental shelf. Continental shelf Continental slope Continental rise – shallow slope at base of continental slope Abyssal plain – deep ocean basin Submarine canyon Turbidity current Submarine fan or deep sea fan Passive margin Active margin Trench
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Mid-ocean ridge – found in center of ocean, is divergent boundary. Axial valley – valley that runs down the center of the mid-ocean ridge Hydrothermal vents – discovered in 1970s Hydrothermal vent communities – also discovered in 1970s
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Unformatted text preview: No photosynthesis possible (too deep), so chemosynthesis provides food for the organisms there. Chemosynthesis –mechanism for making food using: CO 2 sulfur compounds energy from the heat Chemosynthetic bacteria basis of the food chain Other organisms Crabs Shrimp Tube worms Ophiolite – section of oceanic crust that has been accreted onto edge of a continent Structure: Sediment (Top) Pillow basalt Sheeted dikes Gabbro Mantle (Bottom) Atoll – Horseshoe- or ring-shaped coral island surrounding a submerged hot spot volcano Seen most often in the Pacific (south Pacific especially, like Bikini Atoll). Some in Indian Ocean as well (Maldives) In center of atoll is a lagoon Beneath lagoon is a submerged volcano Volcano is submerged because of a combination of: Erosion Subsidence after the volcano moves away from the hot spot...
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This note was uploaded on 01/17/2012 for the course GEOL 1054 taught by Professor Dr.bethrinard during the Fall '09 term at Tarleton.

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OceanFloor - No photosynthesis possible (too deep), so...

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