Planet Earth Exam 4 Study Guide Challenger Expedition 1862 1876 Charles Wyville Thomson Chief Scientist Continental shelves mid ocean ridges deep sea trenches and depth of ocean predicted I Marine Geology 4 700 new species discovered Deep Sea Drilling Projects 1968 Glomar Challenger 15 years sailing First research vessel designed for drilling and taking core samples from the bottom of the ocean 60 miles of core from over 600 sites Proved definite proof of Sea Floor Spreading Began Paleocenography how ocean basins had changed Dynamic Positioning able to change drill bit and re enter drill hole Ocean Drilling Projects replaced DSDP 1985 2003 JOIDES Resolution International effort 110 expeditions 2000 deep sea cores Explore study the composition structure and history of Earth s ocean basins 2004 IODP still have JOIDES Resolution U S Chikyu Japan Mission specific platforms Europe run Mission specific platform L Bkayd Self elevating vessel 40 50ft above sea level Riserless use sea water to flush out JR Riser Chikyu sealed can use heavy drilling mud cake off sands won t collapse hole Different types of Margins Passive Margin East Coast Continental Crust Ocean Crust Locked together Active Margin deep ocean trench Plate boundary ocean trench one plate is being sub ducted underneath another into the mantle Pacific Continental Shelf Broad flat from shoreline to continental slope 0 005 slope 200m deep may extend 100 s km offshore Underlain by continental crust On an active margin less continental shelf On NJ shoreline Continental shelf 135m 1 1000 Not much deposition on Continental Slope Dominant Sediments sand silt mud Shallow shelf affected by tidal wave currents Formed by weathering and erosion of the Appalachian Mtns Coastal Plain landward extension of continental shelf Has been flooded in recent past 20 50 mil yrs Epicontinental Sea western interior seaway Built a glacier move sea level down Features of a Continental Slope Shelf Submarine canyons Continental Shelf off of NJ not all canyons have rivers Exit too deep Movement of a turbidite 15 30 Quake Turbidity Currents Turbidity currents are underwater deep density and gravity driven sediment flows Turbidite formed when earthquake mixes sediment into water and then flows down 1929 Grand Banks 3 30pm 1st cable broke 4 30pm next cable 6 30pm getting further away from 13 hrs last cable broke 770 km away from epicenter Under sea current that moved down the hill and broke the cables Underwater slump Bottom of Slope Continental Rise Submarine Canyon Fan System a few km to over 2000 km across Sediment fines from apex to move distal parts Abyssal Plains beyond the continental rise deep sea Quiet ocean seafloor flattest places on earth Flat because it has covered over any irregularities Forms LARGEST part of ocean Seamounts submerged volcanoes in abyssal plains Abyssal plains are more common in the Atlantic than the Pacific Lithogenic Derived from land near continent Terriogenous derived from continents turbidites Pelagic Clays barren regions below the CCD with only eoilian volcanic and cosmic sources for mud Wind Derived atmosphere Biogenic Sediment derived from organisms Carbonate Ooze 48 percent of ocean floor accumulates Siliceous Ooze sediments are concentrated in regions of upwelling ocean currents Hydrogenic precipitated from water Maganese Nodules very slow growth a few cm per mil yrs Biogenic Sediments formanifers calcium carbonate bugs Siliceous Diatoms oxygen in atmosphere symmetrical skeletons Distribution of carbonate sediments CCD Calcium Carbonate Destruction dissolve destroy carbonate Deepest parts of the ocean cannot have carbonate Dilution by other particles Productivity reproduction of organisms Destruction calcium carbonate dissolves Carbonate Compensation Depth 1 Dilution and terrigenous 2 Destruction and carbonate 3 Productivity Nutrients Siliceous Silica Deposited II Groundwater Hydrologic Cycle Reservoir any environment where water is stored Distribution of Water Oceans 96 Glaciers 3 Groundwater 1 Surface Water 0 01 Atmosphere 0 001 Biospehere 0 0001 powered by the sun atmosphere provides the link water from oceans carried onto land On Earth s Surface Run off Hydrologic Cycle water being transformed from the oceans to the atmosphere by evaporation 434 units lifted from ocean to atmopshere thousands cubic km of water per year 398 units rain back into the ocean 71 units from land put into the atmosphere Evopotransporation Evaporation Transpiration Infiltration water that soaks into the ground source of ground water 2nd largest source of fresh water is groundwater Importance of Groundwater groundwater supplies 40 50 of US population Cheapest source of water NJ 36 of coastal plain drinking water is from groundwater Aquifer sediment rock through which water flows easily Porosity the percent of the total volume of a rock that consists of pore spaces A very porous rock contains a large proportion of pore space Sand 20 porosity Clay 50 porosity Gravel 25 Shale 5 Limestone 25 Sandstone 10 30 Lowest in igneous and metamorphic rocks 0 sometimes What makes a difference is sizes and shapes of particles compactness of the arrangement cement igneous and metamorphic rocks have low porosity except where they are fractured Permeability the capacity for transmitting fluids Sands have high permeability Permeability small holes and small connectors do not allow the water to pass through this is what happens in clay Sandstone Shale little no porosity Low porosity usually means low permeability but high porosity does not mean high permeability In gravel the openings are large but the stuff is usually many sizes and the pores get clogged Clay high porosity no permeability Fractured Shale has secondary permeability due to fractures How does it get down there if you dig deep enough there will be water may not be usable 50 of groundwater is 1 km not much below a few kms down most rain fall flows downhill runoff some soaks into the ground Water slowly sinks into the soil due to gravity Zone of aeration open spaces are normally filled with air Water Table top of saturated zone Zone of saturation spaces are filled with water Aquifers examples sand gravel weathered limestone fractured igneous rock Confining Beds sediment rock that restricts the flow of water Example clay Unconfined intersects the surface yellow sand aquifer 400 feet up Confined bracketed by confining beds white confining bed Geologic work of Ground water groundwater combines with