Download Ocean Waters and the Ocean Floor

"Ocean Waters and the Ocean
Floor"
The Vast World Ocean
• 71% of Earth is covered with water (about 140/197
million square miles)
The Northern Hemisphere is 61% water 39%
land, while the Southern Hemisphere is 81%
water, 19% land.
The total volume of all the land on the Earth
is only 1/18 of the total volume of water.
• The average depth of any of the oceans is 12,500
feet.
• The Pacific Ocean is the largest, and contains
that Marianas Trench - the deepest place
anywhere on Earth.
Composition of Sea Water
• For every thousand parts of sea water, 35 parts are
salt. This can be expressed as 35 ppt (parts per
thousand). This is also called salinity, or the ratio of
salts to pure water.
• Salt is mainly sodium chloride, or common table
salt.
• 8 different elements make up the 5 types of salt.
• In areas of heavy precipitation, the salt
concentration is less.
• In areas of high evaporation, there is more parts of
salt per thousand parts of sea water.
• Extremes in salinity: The Red Sea has about 42 ppt,
while the Baltic Sea has only 10 ppt.
Where does salt come from?
• Chemical weathering on land and runoff into the
ocean brings about 2.5 billion tons of salt per year.
-Volcanic eruptions, and the process of outgasing
emits water and dissolved gases into the ocean and
atmosphere.
-The amount of salt in the oceans hasn't changed, as
various ocean-dwelling plants and animals use salt
in different ways.
Resources from Sea Water
• -Salt, magnesium, and bromine are valuable
resources. Salt is extracted by a process called Solar
Salt Production
-In the 1960's, a lot of these products were taken out
of the ocean. Now, the USA uses the Great Salt Lake
as a resource rather than the ocean.
-Freshwater - desalination can be a costly process,
and it is a small production.
-Even gold can be taken of the ocean, but the
concentration is extremely low. Click on the picture
to read about the Meteor expedition lead by
Germany after WWI.
Meteor Expedition
The Ocean' Layered Structure
• -Temperature and salinity vary with depth.
-The surface mixed zone is the warmest and
makes up 2% of all the oceans.
-The transition zone is the next warmest and
makes up 18% of the oceans.
-The deep zone is the coldest and makes up 80%
of all the oceans.
-A thermocline is a change in temperature
-A halocline is a change in salinity.
Earth Beneath the Sea
• -The H.M.S. Challenger was one of the first ships to do
extensive oceanic studies.
-The echo sounder was an innovation that allowed for a
lot of research to be able to be conducted about the
ocean's floor.
-Here is a problem: Sound travels 5000 ft. per second
through water. It takes one second for the echo to go
from the ship and then be bounced off the bottom and
return to the ship. The total distance is 5000 feet, so you
know from the ship to the ocean floor it is half of that, or
2500 feet. The formula
1/2(5000)(time traveled) can be used anytime.
H.M.S. Challenger
Continental Margins
• Click here to learn more about continental
margins, continental slope & rise.
Submarine Canyons and Turbidity Currents
• -Submarine canyons, steep walled underwater
vallies, are created by turbidity currents. Click on
the links to learn more about them.
The Ocean Basin Floor
• -30% of the Earth's surface are made up by these
landforms:
-Deep ocean trenches, where 2 converging plates meet,
are the deepest regions of Earth. The Marianas trench
can reach up to 36,000 ft. deep.
-Abyssal plains are very flat regions made of the
sediment carried by turbidity currents.
-Seamounts are isolated volcanic peaks made by
hotspots, like Hawaii. Others are near ocean ridges.
Others emerge as land, like St. Helena.
Below From left: A deep ocean trench, the topography of
an abyssal plain, and the location of some seamounts
across the globe.
Trench
Abyssal Plain
Seamounts
Mid Ocean Ridges
• This is where sea floor
spreading occurs, and new
crust is formed.
-These regions make up to
20% of the Earth's surface
-They run a course of
40,000 miles around the
Earth that looks like a
baseball seam.
-Click here to learn about
the Mid-Atlantic Ridge
(below, the MAR is on land
in Iceland)
Coral Reefs and Atolls
• Coral reefs are made of skeletal remains from coral
polyps and algaes.
• They live in warm waters, above 75 degrees F
anually.
• The H.M.S. Beagle expedition
did research atolls and their
locations.
• Atolls are islands made out
coral.
of
Seafloor Sediments
• -Seafloor sediments can be up to 6 miles deep in some
places
-It is mainly mud
-There are 3 broad categories of sediment:
-Terrigenous, which are minerals that were weathered
from continental rocks and then brought to the ocean.
-Biogenous, which is made of shells and skeletons of
marine life.
-Hydrogenous, which are minerals that crystallize from
seawater. Manganese nodules are a type of this kind of
sediment. They are one of the slowest chemical reactions
known.
Seafloor Sediments and Climate
Change
• -Scientists use sediment from the ocean floor to
examine past climates, using shells from old
animals that died and became incorporated into
the sediment.
-Deep ocean drillings also help to determine
climates from periods of time lke te ice age. Click
to learn about the JOIDES Resolution ship from
the Ocean Drilling Program
Joides Resolution
• Plate Tectonics