Download The Ocean Floor - isd194 cms .demo. ties .k12. mn .us

Exploring the Oceans
Chapter 13
Oceans of the Earth
• 71% of Earth’s surface is water
• 98% of water on Earth is ocean water
What/where is the rest of Earth’s water?
• Oceans are gradually changing shape due
to plate tectonics
Which ocean is growing larger?
Composition of Ocean Water
• The salinity of ocean water is 3.5% (for every
100mL of water 3.5 grams is salt)
• Salt = dissolved elements in water, sodium and
chlorine, most abundant-but there are many
other salts, among them Mg, K, S, and Ca
What do Sodium (Na) and Chlorine (Cl) combine to
form?
Ocean Water
Ions
Composition of Ocean Water
Sources of Salt:
1. Minerals in ocean crust
2. Erosion of land minerals carried to oceans by
rivers
• Minerals are continually added to water by
above
Why aren’t oceans getting saltier?
Or are they? Lets talk about this.
The Answer
Composition of Ocean Water
How salts are removed:
1. By winds
2. Sea spray = waves breaking on shore
3. Used by organism for shells and for nutrients
4. Become part of new ocean crust
Ocean Temperature and Pressure
• Oceans surface warmed by the sun
• Suns rays only go so deep, which leads to a
top, fairly uniform layer = surface zone
• Beneath surface zone is thermocline = layer
in which water temp. decreases rapidly with
depth
• Below thermocline is deep zone: temps
decrease slowly
Ocean Temperature and Pressure
• Pressure increases with depth, more water
present to push down, and in all directions
• Pressure affects freezing temp. along with salt
in the water causing deep ocean water to
actually be below freezing as a liquid
Effects of salt on freezing point
Ocean Chemistry
Depth
Surface zone
Transition zone
0.5
km
1.0
km
1.5
km
2.0
km
2.5
km
3.0
km
3.5
km
3.8 km
Average ocean depth
4.0
km
Deep zone
The Ocean Floor
Measuring the Water’s Depth
• Done w/an echo sounder by bouncing sound
waves off the bottom and measuring how long
it takes waves to come back
• This creates a side view or profile of the ocean
floor
The Ocean Floor
Features of Ocean Floor:
Continental Shelf = broad flat extensions of
continent submerged by water
Continental Slope = steep slope that marks the
end of continental shelf, extends down to
ocean floor
The Ocean Floor
Features of Ocean Floor:
Continental Rise: sand and mud washed down
the continental slope forming small hill of
deposits
Abyssal Hills: hills on the ocean floor
Abyssal Plains: flat surfaces of the ocean floor
The Ocean Floor
Features of Ocean Floor:
Seamount: extend at least 900 meters off ocean
floor, usually either exticnt or forming
volcanoes
Guyots: seamounts that have had their tops
eroded flat
The Ocean Floor
Features of Ocean Floor:
Mid Ocean Ridges: form where two ocean plates
are splitting apart, magma erupts creating new
ocean crust
Trenches: form when an ocean plate sinks under
a different plate
The Ocean Floor
Continental slope
Continental shelf
Volcanic island
Seamount
Abyssal plain
Continental
slope
Mid-ocean ridge
Continental shelf
Trench
Ocean Zones
Beach
Intertidal
zone
High-tide
line
Low-tide
line
Neritic zone
Open-ocean zone
Surface zone
Continental shelf
Continental
slope
Deep zone
The Ocean Floor
Seamounts and
trenches
Ocean floor
features
include
Abyssal plains
Mid-ocean ridges
Sea-Floor Spreading
Sea-Floor Spreading
Sea-Floor Spreading
Sea-Floor Spreading
Mid-ocean ridge
Oceanic crust
Mantle
Sea-Floor Spreading
Mid-ocean ridge
Oceanic crust
Mantle
Magma
Sea-Floor Spreading
Mid-ocean ridge
Sea-floor spreading
Oceanic crust
Mantle
Magma
Sea-Floor Spreading
Newly formed
oceanic crust
Sea-floor spreading
Oceanic crust
Mantle
Magma
Mid-ocean ridge
Sea-Floor Spreading
Old oceanic crust
Newly formed
oceanic crust
Sea-floor spreading
Oceanic crust
Mantle
Magma
Mid-ocean ridge
Sea-Floor Spreading
Old oceanic crust
Continental
crust
Newly formed
oceanic crust
Sea-floor spreading
Oceanic crust
Mantle
Magma
Mid-ocean ridge
Sea-Floor Spreading
Old oceanic crust
Continental
crust
Newly formed
oceanic crust
Sea-floor spreading
Oceanic crust
Mantle
Old oceanic
crust melts
Magma
Mid-ocean ridge
Plate Tectonics
Sea-Floor Spreading
forms
Oceanic
crust
Mid-ocean
ridge
erupts
through
subducted
through
Deep-ocean
trenches
Molten
material
forms
Sea-Floor Spreading
forms
Oceanic
crust
Mid-ocean
ridge
erupts
through
subducted
through
Deep-ocean
trenches
Molten
material
forms
Sea-Floor Spreading
forms
Oceanic
crust
Mid-ocean
ridge
erupts
through
subducted
through
Deep-ocean
trenches
Molten
material
forms
Sea-Floor Spreading
forms
Oceanic
crust
Mid-ocean
ridge
erupts
through
subducted
through
Deep-ocean
trenches
Molten
material
forms
Ocean Resources
Seawater can be used as a resource for drinking
and irrigation if the salt is removed = desalting
One method of desalting = distillation
Distillation = water is evaporated to vapor leaving
the salts behind, the water then condenses and
this fresh water is then collected