The oceans are a
connected system.
Section 3.1C
Ocean water covers most of
Earth.
• Different sections of the ocean have different
names; however, all the sections are connected.
• http://www.polarhusky.com/ocean/geography/5-oceans/
How did Earth become covered
by an ocean?
• Earth formed about 4.6 billion years ago as a ball of
molten rock.
• Heavier material sank to the core, and lighter
materials floated toward the surface.
• Water vapor rose to the cooler surface.
• About 4 billion years ago, Earth had cooled enough
for the water vapor to become liquid.
• http://www.history.com/shows/how-the-earth-wasmade/videos/oceans#the-age-of-earth
Ocean water contains salts and
gases.
• The ocean contains all 92 elements that occur in
nature, although most are in very tiny amounts.
Salts
• Salinity is a measure of the amount of dissolved salt
contained in water.
• The ocean contains many different kinds of salts, but
sodium chloride accounts for most of the ocean’s
salinity.
• Over time, rain and rivers wash some of the elements
that make up salts into the sea.
• They also enter ocean water when underwater
volcanoes erupt.
Density
• Water that contains dissolved solids, such as salts, is
heavier than the same amount of water with no
dissolved solids.
• Salt water has a greater density than fresh water.
• The higher the water’s salt content, the greater its
density.
• The denser the water, the more easily things float in
it.
The Dead Sea
• The Dead Sea is the lowest place on Earth, roughly
1,300 feet below sea level.
• It is fed by the Jordan river, with no outflow.
• The quantity of water that evaporates from it is
greater than that which flows into it, and this body
of water has the highest concentration of salt in the
world.
The Dead Sea (continued)
• http://maps.google.com/maps?q=the%20dead%
20sea%2C%20map&hl=en&safe=active&rls=co
m.microsoft:enus&prmd=ivns&gs_sm=e&gs_upl=32485l33266l
0l33579l5l3l0l0l0l0l312l765l22.1l3l0&um=1&ie=UTF-8&sa=N&tab=il
• https://www.youtube.com/watch?v=aTcyACmiah
o&feature=related
Some parts of the ocean are
saltier than others.
• When water evaporates, salt is left behind, and water
is saltier.
• It is especially salty in shallow areas and warm
climates.
• Salinity is also higher in areas where ocean water
freezes. Ice forms on the ocean, and the salt is left
in the water below.
Some parts of the ocean are
saltier than others (cont.).
• Salinity is lower in areas where the ocean is diluted
by fresh water.
• where rivers empty into the ocean
• in areas where a lot of rain falls
Oxygen and Other Gases
• Oxygen and other gases dissolve in water and are
essential to ocean life.
• Ocean animals take in oxygen and give off carbon
dioxide.
• Oxygen and carbon dioxide get mixed into the ocean
from the air above the ocean’s surface.
• Oxygen is also added by plants and algae that live
near the surface.
Oxygen and Other Gases (cont.)
• Carbon dioxide is a building block of ocean animals’
shells.
Ocean temperatures vary.
The Surface Layer:
• Heated by the sun and mixed by winds and waves
• Warmest layer = less dense = stays at the surface
The Thermocline:
• Lies below the surface layer
• Temp. drops fast with depth
The deep water
• Cold all year
• Temp. of the water at the ocean’s bottom is around
0°C-3°C (32°F-37°F), at or barely above freezing
Ocean Layers
Ocean temperatures vary (cont.).
• Surface temp. varies by location and season.
• Surface temp is warmer near the equator than near
the poles.
• Warmer in the summer and cooler in the winter
The ocean floor has many
features.
Continental Shelf
• The flat or gradually sloping land that extends
underwater from the edge of a continent to a
continental slope
Continental Slope
• Land that drops down steeply a the edge of a
continental shelf
Submarine Canyons
• Cut through the continental shelf and slope
Ocean Trenches
• Narrow, steep-sided clefts in the ocean floor
Abyssal Plain
• A wide, flat area of ocean floor that is covered with a
thick layer of sediment
Seamounts
• Undersea mountains
Volcanic Islands
• Underwater volcanoes tall enough to reach above the
surface
Mid-ocean Ridge
• A chain of mountains that run through an ocean basin
Ocean Exploration
• Obstacles – pressure, darkness, lack of air, chilling
cold
• Scuba equipment: can spend about an hour under
water; can safely reach depths as great as 40 meters
(130 feet)
• Deeper: small submarines or robots equipped with
cameras
Mapping the Ocean Floor
• Sonar – a system that uses sound waves to measure
distances and locate objects
• Ships aim sound waves at the ocean’s bottom and
measure the time it takes to receive the echo
• Fast echo = bottom is shallow
• Slow echo = bottom is deep
• Sonar is good to use for detailed images of small
areas of the ocean floor.
• Satellite imaging is used for large areas.
• It can detect tiny bumps and dips in the ocean’s
height. Small surface differences reveal the shape of
the ocean floor.
Mapping the Ocean Floor (cont.)
Mapping the Ocean Floor (cont.)
•
http://player.discoveryeducation.com/index.cfm?guidAssetId=D8F853D5-9378-46B8-AB13-0000AB382818&blnFromSearch=1&productcode=US