3 Mapping the ocean floor quiz 1)When the ocean is emptied, what does the sea floor look like?2)What device is used to take samples from the ocean floor?3)What device is used to map the ocean floor in detail?4) What was the significance of the electronic jellyfish on the ROV?5)Where did the Dumbo octopus get its name?6)What are underwater volcanoes called?7)Where do you find deep sea corals?8)How tall are the corals in the strait of Fl?9)What is the mid-oceanic ridge?10)Where is it exposed?11) What is the largest underwater landscape?
4 World oceanThough generally described as several 'separate' oceans, these waters comprise one global, interconnected body of salt water sometimes referred to as the World Ocean or global ocean.This concept of a continuous body of water with relatively free interchange among its parts is of fundamental importance to oceanography.
5 The major oceanic divisions (largest to smallest): Pacific OceanAtlantic OceanIndian Ocean(Southern Ocean)Arctic OceanSouthern Ocean, which, unlike other oceans, has no landmass separating it from other oceans and is therefore sometimes subsumed as the southern portions of the Pacific, Atlantic, and Indian Oceans, which encircles Antarctica and covers much of the AntarcticArctic Ocean, sometimes considered a sea of the Atlantic, which covers much of the Arctic and washes upon northern North America and Eurasia
7 Ocean floorFlat and Lifeless?Varied Landmarks and full of Life?
8 Sea Level Ocean’s average height relative to land. Throughout history sea level has changedShifts in climateGrowing or shrinking ice capsIce ages = more landMore water frozen in iceWarm periods = less landMore water is liquid
10 Ocean Average Depth is ~12,081 ft Deepest part of the ocean Mariana Trench(~36,200 ft)Same as on landHills, valleys, mountains, etcOcean is home to tallest mountains, widest plains and deepest valleys
11 bathymetry Characteristics of the ocean floor The surfaces of the Moon and Jupiter have been mapped more thoroughly than the floor of the sea.
12 Ocean floor Mt Everest vs. Mauna Kea Which one is which? Mauna kea in hawaii 4, 205 ft are above sea level
13 The Vast UnknownOn January 7, 2005, only 400 miles from its base on Guam, the navy submarine USS San Francisco was traveling about 35 mph when it slammed into an uncharted mountain about 6,000 feet beneath the surface.One crew member died and 23 others were injured.
14 Ocean floorThe familiar landscapes of continents are mirrored, and generally magnified, by similar features in the ocean basin.The largest underwater mountains, for example, are higher than those on the continents.Underwater plains are flatter and more extensive than those on the continents.All basins contain certain common features that include oceanic ridges, trenches, abyssal plains, and volcanic cones.
16 1) Continental MarginRegion closest to land that is made up of 3 parts.
17 1a) Continental shelfGently sloping land area along the edges of continents
18 1b) Continental slopeSteep slope leading from the edge of a continent down to the seafloor
19 1c) Continental RiseHill of sediment at the bottom of the steep slope near the edges of continents
20 2) Abyssal plainsFlat, featureless plain making up a large part of the seafloorThey tend to be found at depths of meters.Oceanographers believe that abyssal plains are so flat because they are covered with sediments (clay, sand, and gravel) that have been washed off the surface of the continents for hundreds of thousands of years.More extensive in Atlantic and Indian Ocean because of constant river input of sediments.
21 Seafloor sedimentsCovering the abyssal plains are seafloor sediments that have different origins.3 types:1) Terrigenous – Consists of mineral grains eroded from land.2) Biogenous – Consists of shells and skeletons of marine animals and algae.3) Hydrogenous – Consists of minerals that crystallize directly from ocean water.
22 3) mid-ocean ridgeUnderwater mountain range, where new seafloor is created.Atlantic Mid-Ocean Ridge is largest in the world.Enormous mountain ranges, or oceanic ridges, cover the ocean floor.The Mid-Atlantic Ridge starts at Greenland, runs down the center of the Atlantic Ocean and ends at the southern tip of the Africa.At that point, it stretches around the eastern edge of Africa, where it becomes the Mid-Indian Ridge.Some scientists say this is a single oceanic ridge that encircles Earth, one that stretches a total of more than 40,000 miles.
23 Ocean ridgesIn most locations, oceanic ridges are 2,000 meters or more below the surface of the oceans.In a few places, however, they actually extend above sea level and form islands. Iceland, the Azores (about mi. off coast of Portugal), and Tristan de Cunha are examples of such islands.
24 4) mid-ocean ridgeScientists believe ocean ridges are formed when magma emerges from Earth’s interior, a process known as seafloor spreading.Alfred Wegener developed continental drift theory, PangaeaWhich led to Harry Hess’s proposal of seafloor spreading
25 5) trenchesDeepest feature of the ocean, plunging deep below the seafloor.Trenches are long, narrow, canyon like structures, most often found next to a continental margin.They occur much more commonly in the Pacific than in any of the other oceans.The deepest trench on Earth is the Mariana Trench, which runs from the coast of Japan south and then west toward the Philippine Islands—a distance of about 1,580 miles.The British naval vessel, Challenger II surveyed the trench in 1951 and named the deepest part of the trench, the "Challenger Deep".Trenches are long, narrow, canyon like structures, most often found next to a continental margin.They occur much more commonly in the Pacific than in any of the other oceans.The deepest trench on Earth is the Mariana Trench, which runs from the coast of Japan south and then west toward the Philippine Islands—a distance of about 1,580 miles.The British naval vessel, Challenger II surveyed the trench in 1951 and named the deepest part of the trench, the "Challenger Deep".
27 5) TrenchesIts deepest spot is 11,033 meters below sea level called the Challenger Deep in the Marianas Trench.Earthquakes and volcanic activity are commonly associated with trenches.Mariana Trench Video – 45 min
29 6) Volcanic conesOcean basins are alive with volcanic activity. Magma flows upward from the mantle to the ocean bottom not only through rifts, but also through numerous volcanoes and other openings in the ocean floor.a) Seamounts are submarine volcanoes and can be either active or extinct.b) Guyots are a specific type of seamount with a flattened top.Extinct volcanoes that were once above sea level but have since receded below the surface. As they receded, wave or current action eroded the top of the volcano to a flat surface.
32 7) Submarine canyonSteep-sided underwater valley near the edge of a continent.
33 Ocean We know more about our moon and Mars than our Ocean Only Mapped 10% of the ocean floorWhy?
34 Ocean The moon and mars we can see Ocean we cannot…water impedes a lot Pressure visual, etcNeed to understand thisShipping routesNational securityAnimals migrationsEarth’s final frontier
35 Early Measurements Line with a weight on the end Knots tied at different pointsThrow overboard and see at what knot the line is at and recordKnots are called Plumb linesEarly maps of the ocean floor
36 Post World War I Measurements Sound WavesSonar – Sound Navigation and RangingUse echoesSounds “pings” bounce off the floor and time returnLike sound in an empty classroom versus a gymMust know how fast sound travels in waterEarly Mapping of Red Sea
38 Sound in waterSound in water travels much faster than sound in air travelsAvg speed is 1500 m/s (3000 miles per hour)Air = 340 m/sCan measure depth using:D= (1/2) T*VSea depth = ½ Time * Velocity½ because 1T = surface to floor and then floor to surface
39 Today’s Sonar Sophisticated Sonar technology Side Scan and Multibeam Locates shipwrecks, downed planes, schools of fishSide Scan and Multibeam
40 Side Scan Tow fish dragged behind a ship or attached to submersible Computer generates imageReceives INTENSITY rather than basic sonarHard objects = more intense beamsMetal ship and rocksSoft objects = less intenseMud and SandBlack areas are acoustic shadows…no soundPictures of Seafloor, but not depthGood at locating
41 Multibeam Depth Measurements Emit pulse of sound from ships hull Data are recorded at a wider angleDifferent Depths = Different Colors
43 Lab: A classroom model of the ocean floor Page 95-97
44 Echolocation Animals that are unable to see in the dark Determine distance and direction of objectsBats = find food or navigate trees or cavesToothed WhalesSend out clicksSound travels more efficiently in water than airMELON in their headLarge fatty organFocuses the soundSounds received from cavities in lower jaw
46 Slow Process Ocean is so immense Use data from space Very difficult and expensive to cover entire floorUse data from spaceHighs and lows of sea surface mirror seafloorUse satellites to measure underwater topography = BATHYMETRY
47 A few more detailsNeed to look at ocean topography to understand why and where animals migrate, how things are related and what is going on there with currents, weather etc
48 Sea Level ChangesSea Level changes throughout history have changed the geography of the land and the continental shelvesNorth America was once covered by a seaCoral Fossils in Boulder mountains
49 Seafloor Sediments Diverse and complex Variety of abiotic and biotic factorsDiffer depending on the type of material they come fromLand = TERRIGENOUS sedimentsLiving organisms = BIOGENOUS sedimentsSmaller portion from chemical reactions
50 SoilsTerrigenous sediments are primarily abiotic materials (rock & debris) that are broken downCarried by water, wind or ice (erosion) to the oceanAs they move, they bump against other objectsSmoothing the surfaceComposition depends on the parent materialWhite vs black beaches?
51 Sediment types Black Soil – Hawaii – Eroded volcanic rock White – Quartz based from granite rock or biogenous
52 SedimentBiogenous comes from broken parts of shells of marine organismsCommon source is from microscopic phytoplanktonWhere there are lots of planktonSea floor is typically biogenousSome white sand beaches made exclusively of theseSome biogenous sediments come from weathering of coral reefsOpen ocean, as quartz and terrestrial materials is limited the farther you go
53 Sediments tell us history Information about physical ocean science processes, biological health and past climate
54 Sediments HYDROGENOUS sediments COSMOGENOUS sediments Precipitate out of seawaterVery mineral-richCOSMOGENOUS sedimentsDust and large particles from spaceVery tiny fraction
55 Sediments and Migrations Sediments are important for animal travelsSome feed on resources in certain soils and others have to dive deeper
56 Ocean zones The ocean can be divided into two basic regions: A. Pelagic Zone (anywhere in the water column)B. Benthic Zone (the seafloor)
57 Pelagic Zone The Pelagic Zone is further divided horizontally into: Neritic Zones (Coastal oceans) – Nearshore.- large variety of conditions- Salinity can increases by evaporation, or decrease from river input- Temperature changes rapidly- Most biologically productive part of the seaOceanic Zones (Open Ocean) – Offshore.- Open ocean- 90% of the world’s ocean
59 Pelagic zone Epipelagic zone – (0-200 meters) Can also be divided vertically into:Epipelagic zone – (0-200 meters)Mesopelagic Zone (200–1000 meters)Bathypelagic Zone – ( meters)Abyssalpelagic Zone – ( meters)Hadalpelagic – (6000 – 10,000 meters)
62 splash ZoneSupralittoral (splash zone) – rarely if ever covered with waterIntertidal/littoral Zone – Regularly submerged and exposed with the fluctuating tide levelsSublittoral (sub – tidal) Zone – which extends to the edge of the continental shelf.