Download Earth Science Chapter 20

Bell Ringer
What is a continental slope and
a continental shelf.
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 OceanBasin 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