exploring the oceans chapter 13. oceans of the earth 71% of earth’s surface is water 98% of water...
TRANSCRIPT
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 WaterSources of Salt:1. Minerals in ocean crust2. 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 WaterHow salts are removed:1. By winds2. Sea spray = waves breaking on shore3. Used by organism for shells and for nutrients4. 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
0.5km
4.0km
3.5km
3.0km
2.5km
2.0km
1.5km
1.0km
DepthSurface zone
Transition zone
Deep zone
3.8 kmAverage ocean depth
The Ocean FloorMeasuring 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 FloorFeatures 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 FloorFeatures 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 FloorFeatures 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 FloorFeatures 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 shelf SeamountVolcanic island
Continental slope
Continental shelf
Continental slope
Abyssal plain Mid-ocean ridge Trench
Ocean Zones
Beach
High-tide line
Low-tide line
Continental shelf
Continentalslope
Deep zone
Surface zone
Open-ocean zoneNeritic zoneIntertidal
zone
The Ocean Floor
Ocean floorfeatures include
Seamounts andtrenches
Abyssal plains
Mid-ocean ridges
Sea-Floor Spreading
Sea-Floor Spreading
Sea-Floor Spreading
Sea-Floor Spreading
Mantle
Oceanic crust
Mid-ocean ridge
Sea-Floor Spreading
Magma
Mantle
Oceanic crust
Mid-ocean ridge
Sea-Floor Spreading
Magma
Mantle
Oceanic crust
Sea-floor spreading
Mid-ocean ridge
Sea-Floor Spreading
Magma
Mantle
Oceanic crust
Sea-floor spreading
Mid-ocean ridge
Newly formedoceanic crust
Sea-Floor Spreading
Magma
Mantle
Oceanic crust
Sea-floor spreading
Mid-ocean ridge
Newly formedoceanic crust
Old oceanic crust
Sea-Floor Spreading
Magma
Mantle
Oceanic crust
Sea-floor spreading
Mid-ocean ridge
Newly formedoceanic crust
Old oceanic crust
Tren
ch
Continentalcrust
Sea-Floor Spreading
Magma
Mantle
Oceanic crust
Sea-floor spreading
Mid-ocean ridge
Newly formedoceanic crust
Old oceanic crust
Tren
ch
Continentalcrust
Old oceaniccrust melts
Plate Tectonics
Sea-Floor Spreading
Mid-ocean ridge
Molten material
Oceanic crust
Deep-ocean trenches
eruptsthrough
forms
subductedthroughforms
Sea-Floor Spreading
Mid-ocean ridge
Molten material
Oceanic crust
Deep-ocean trenches
eruptsthrough
forms
subductedthroughforms
Sea-Floor Spreading
Mid-ocean ridge
Molten material
Oceanic crust
Deep-ocean trenches
eruptsthrough
forms
subductedthroughforms
Sea-Floor Spreading
Mid-ocean ridge
Molten material
Oceanic crust
Deep-ocean trenches
eruptsthrough
forms
subductedthroughforms
Ocean ResourcesSeawater 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