Download Earth Science Chapter 20 20.1 The Water Planet 20.1 The Water

Earth Science Chapter 20
20.1 The Water Planet
20.1 The Water Planet
•¾ of the earth’s surface lies submerged beneath salt water called global ocean.
•Earth alone is called the water planet.
•97 % of all the water on earth is contained by the global ocean.
•Mass of the ocean is 1/4000 of the mass of the earth as a whole.
•Volume is about 800 times greater than the volume of water in the global ocean.
Divisions of the Global Ocean
•3 major oceans-Atlantic, Pacific & Indian
•Water at the polar regions are called oceans.
•They are really part of one of the major 3
•Artic is really part of the Atlantic
•Sea is a smaller area of an ocean.
•Ex. Mediterranean, Caribbean, & Coral Sea
•Water in the Artic is less salty than the other oceans.
•Pacific is the largest and deepest
•The 2nd is the Atlantic which contains the Mediterranean, Caribbean, Gulf of Mexico
and Baltic Sea.
•Indian is the 3rd largest and contains the Arabian and Red Sea.
Exploration of the Ocean
•Oceanography is the study of the physical characteristics, chemical, composition & life
forms.
•American naval officer, Matthew Maury used records from navy ships to learn about
ocean currents, winds, depths, & weather conditions.
Challenger
•British Navy ship H.M.S. Challenger laid the foundation for modern science of
oceanography.
•Team crossed the big 3 oceans and collected the data of water temperatures, depth of
oceans, and samples of ocean water, sediments, and 1000’s forms of marine life.
Joides Resolution
•World’s largest and most sophisticated scientific drilling ship.
•Provided scientists with valuable data about plate tectonics and the ocean floor.
•Floor is made up of continental crust and oceanic crust that lies beneath the ocean
waters.
Submersibles
•Underwater research vessels, that enable oceanographers to study ocean depths.
•These are referred to as submarine robots.
•Jason Jr.
•Perform tasks ranging from photographing the ocean to collecting mineral samples.
Bathysphere
•Spherical diving vessel that was first used for deep-ocean exploration.
•Carried by an area of the ocean sphere, which carried scientists, but stayed connected to
the research ship & life support.
Bathyscaph
•Research ship self-propelled, free moving submarine equipped for deep ocean.
•Alvin is a craft that holds a pilot and two scientists.
•Alvin has made over 2000 dives.
•Found marine life in deep hydrothermal water (hot water).
Robot submersibles
•Study at great depths for long periods of time.
•Argo was a seeing-eye robot vessel, that located the luxury ship called the Titanic.
Sonar
•Research ships and submersibles are equipped with sonar to aid in mapping the ocean
floor.
•Sonar is an acronym for sound navigation and ranging.
•Consists of a transmitter an receiver.
•Bounces off the solid ocean floor and reflected back up to the receiver.
•Measures the amount of time it takes to bounce back
Bell Ringer
What is a continental slope and a continental shelf.
20.2 Features of the Ocean Floor
•Divide into 2 major areas: continental margins and deep ocean basin.
•Continental margins are shallower portions of the ocean floor. Consists of continental
crust and thick wedge sediment.
•Deep ocean basin is made up of oceanic crust and thin sediment.
Continental Margins
•Part of the continental shelf and continental slope.
•Real boundary lies offshore.
•Part of the continent that is covered by ocean water is called the continental shelf.
•Water above is shallow.
•Are affected by changes in sea level.
•Continental shelf along the east coast of the US has an average of 70 km in width.
•Shelf along the west coast has an average width of 170 km.
Continental Slope
•At the seaward edge of the continental shelf is a steeper slope called the continental
slope.
•Boundary between the continental crust and the oceanic crust is found at the base of the
continental slope.
•Continental shelf & continental slope may be cut by deep V-shaped valleys.
Submarine canyons
•These are deep valleys.
•Often associated with the mouths of major rivers.
•Other canyons may have been caused by turbidity currents.
•The turbidity currents are dense currents that carry large amounts of sediments down the
continental slope.
Continental Rise.
•Sediments that form a raised wedge at the base of the continental slope.
•These sediments are deposited as the turbidity currents slow down.
Deep Ocean Basins
•Distinctive features include:
broad, flat plains, submerged volcanic mountains, gigantic
volcanic mountain ranges, & deep trenches.
Trenches
•Located in the deep ocean basin and are the deepest features on the earth’s surface.
•Long, narrow places
•Deepest in the world is the Mariana Trench in the Pacific Ocean near the island of
Guam.
•Most are located along the Pacific Ring of Fire.
Trenches continued
•Trenches are associated with earthquakes, volcanic mountain ranges, and volcanic
island arcs.
•Deep trenches in the Pacific Ocean occur offshore from Japan.
•Also, there are trenches found in the Alaska’s Aleutian Islands, the Philippines, & the
west coast of South America.
Abyssal Plains
•Extremely vast flat areas that lie in the deep ocean basins.
•They are found in ocean depths greater than 4 km.
•Cover about half of the deep-ocean basin.
•Flattest regions on earth.
Facts about abyssal plains
•Sonar reveals that the abyssal plains are made of sediments deposited in the deep ocean
basin.
•The abyssal plains of the Atlantic Ocean are close to the continental margins.
Mid-Ocean Ridges
•Most prominent features of the ocean basin.
•Continuous series of underwater mountain ranges that run along the ocean floors.
•Only in Iceland, do mid-ocean ridges rise above sea level.
Facts of mid-ocean ridges
•Form when ridge plates pull away from each other.
•Have narrow depressions called rift.
•A new crust separates and breaks into a series of faults called fracture zones.
Seamounts
•Submerged volcanic mountains at least 1000 m high.
•Submerged volcanic mountains less than 1 km are called abyssal hills.
•Seamounts and abyssal hills are generally associated with hotspots.
•Those that rise above the surface of the ocean form islands such as Hawaii & the Canary
Islands.
Guyouts
•These
flat-topped, submerged seamounts.
20.3 Ocean-Floor Sediments
•Differ from one part of the ocean to another.
•Continental slope and shelves are covered with sediments.
•Samples in the deep-ocean basins are obtained by taking core samples.
(Scoops of
sediments)
Sources of Deep Ocean-Basin Sediments
•Materials may come from organic or inorganic sources.
Inorganic Sediments
•Most of these sediments are deposited along the shore & on the continental shelf.
•Great quantities come from slides.
•Some come from volcanic dust.
•Icebergs provide some sediments.
•Even meteorites contribute
Organic Sediments
•Remains of marine plants and animals.
•2 most common substances are silica and calcium carbonate.
•Silica comes primarily from microscopic organisms (diatoms & radiolaria).
•Calcium carbonate comes from skeletons of tiny organisms called foraminifera.
•Animals like coral and clams also add calcium carbonate to ocean-basin sediments.
Chemical Deposits
•Make up part of the ocean floor sediments.
•Potato-shaped lumps of minerals, or nodules, form on the abyssal plains.
•Composed mainly of oxides of manganese, nickel, & iron.
others
•Phosphorite are also formed directly in the ocean water.
Physical Classification of Sediments
•Two types: Muds and ooze
•1st type is 40 % of ocean floor is covered with a soft, organic sediment called Muds.
•2nd type is ooze.
•30 % of the ooze is made up of organic materials.
Two types of ooze
•1st type is Calcareous ooze and is mostly calcium carbonate.
•Never found in deep ocean water.
•2nd type of ooze is siliceous ooze.
•Siliceous ooze is mostly silicon dioxide.
•Most found in cool, nutrient-rich ocean waters near Antarctica.
Test
•Will come from power point notes, worksheets, section questions, and chapter review
questions.
•Test will be Thursday