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Under the Sea!! Under the Sea!!
The creation and destruction of the sea floor
The creation and destruction of the sea floor
Constant state of changeConstant state of change
Constant creation and destruction through SEAFLOOR SPREADING
New crust emerges from rift valley in MID OCEAN RIDGE
Old floor sinks in the TRENCHES
Whole cycle takes 185 to 200 million years Same rate at which your
fingernails grow!
Constant creation and destruction through SEAFLOOR SPREADING
New crust emerges from rift valley in MID OCEAN RIDGE
Old floor sinks in the TRENCHES
Whole cycle takes 185 to 200 million years Same rate at which your
fingernails grow!
Seafloor spreadingSeafloor spreading
Four types of evidence for sea floor spreading
Four types of evidence for sea floor spreading
Radiometric dating
Sediment samples Rheology Magnetometer
Data
Radiometric dating
Sediment samples Rheology Magnetometer
Data
Radiometric Dating Radiometric Dating Radiometric dating
Determine age of rocks by looking at half life What is half life?
Found that seafloor rock is significantly younger than rock in the center of the continents Seafloor: 200 million years old Continent: 3.9 billion years old
Why is that?
Where would the oldest crust be located on the sea floor?
Radiometric dating Determine age of rocks by looking at half life
What is half life?
Found that seafloor rock is significantly younger than rock in the center of the continents Seafloor: 200 million years old Continent: 3.9 billion years old
Why is that?
Where would the oldest crust be located on the sea floor?
Sediment Samples Sediment Samples
Coring: drilling holes in the ocean floor for samples Level of sediment
buildup on top of the hard ridge
Question: If you know that the youngest ocean floor is near the mid ridge and older floor is near the trenches (continents) which section of the ocean would you expect to have the most sediment?
Alvin
Coring: drilling holes in the ocean floor for samples Level of sediment
buildup on top of the hard ridge
Question: If you know that the youngest ocean floor is near the mid ridge and older floor is near the trenches (continents) which section of the ocean would you expect to have the most sediment?
Alvin
RheologyRheology
Rheology: Study of how matter flows Measure the
temperature of the ocean water
Where do you expect the temperature to be higher? Near the trenches or ridge?
Temperature of water decreases as you move away from the ridge.
Rheology: Study of how matter flows Measure the
temperature of the ocean water
Where do you expect the temperature to be higher? Near the trenches or ridge?
Temperature of water decreases as you move away from the ridge.
Magnetometer Data Magnetometer Data Magnetometer: measures
the polar orientation and intensity of magnetism of minerals 1961 studied the polar
orientation magnetism of seafloor basalt
Minerals are often magnetic and align themselves to the poles as they settle.
Found a pattern Earth reverses its magnetic
poles and the minerals reflected the switch!
Switched about 10 times over 4 million years.
Magnetometer: measures the polar orientation and intensity of magnetism of minerals 1961 studied the polar
orientation magnetism of seafloor basalt
Minerals are often magnetic and align themselves to the poles as they settle.
Found a pattern Earth reverses its magnetic
poles and the minerals reflected the switch!
Switched about 10 times over 4 million years.
Hydrothermal Vents Hydrothermal Vents
Found on the ocean floor well below the photic zone No sunlight
Many unique life forms: clams, giant tubeworms, crustaceans
How can life survive down there? Heated vent provides
adequate temp for productive ecosystems
High levels of dissolved hydrogen sulfide
Chemosynthesizers
Found on the ocean floor well below the photic zone No sunlight
Many unique life forms: clams, giant tubeworms, crustaceans
How can life survive down there? Heated vent provides
adequate temp for productive ecosystems
High levels of dissolved hydrogen sulfide
Chemosynthesizers
Plate Tectonics Plate Tectonics
Seafloor spreading: explanation of how continents spread
Explanation for Island formations away from plate boundaries!
Seafloor spreading: explanation of how continents spread
Explanation for Island formations away from plate boundaries!
Hot Spots = Island ChainsHot Spots = Island Chains
Hot Spots: areas within mantle where thermal plumes cause magma columns to push up intensely, breaking through crust Hot spots do not move
because they are located within mantle
The plate moves over the hot spot over millions of years forming islands in chains
Hot Spots: areas within mantle where thermal plumes cause magma columns to push up intensely, breaking through crust Hot spots do not move
because they are located within mantle
The plate moves over the hot spot over millions of years forming islands in chains
Types of BoundariesTypes of Boundaries
Divergent BoundaryDivergent Boundary
Divergent Boundary: two plates are moving apart Creation of new
sea floor
Divergent Boundary: two plates are moving apart Creation of new
sea floor
Convergent BoundaryConvergent Boundary
Convergent Boundary: two plates are pushed together Oceanic - oceanic convergence Continental-continental convergence Oceanic - continental convergence
Convergent Boundary: two plates are pushed together Oceanic - oceanic convergence Continental-continental convergence Oceanic - continental convergence
Types of Boundaries Diagrams
Types of Boundaries Diagrams
Convection Convection Convection in the mantel drives seafloor
spreading and continental drift Vertical circulation pattern in a gas or liquid
cause by hot material rising and cold material sinking
Convection in the mantel drives seafloor spreading and continental drift Vertical circulation pattern in a gas or liquid
cause by hot material rising and cold material sinking
Pangea Pangea
Pangea In Action Pangea In Action
Changes are still happening today! Changes are still
happening today!
Florida and the Gulf of Mexico Changes in land mass due to
Continental spreading Rising ocean levels
Formed about 300 million years ago and still forming!
Andes are still forming Pacific Ocean is getting smaller
Florida and the Gulf of Mexico Changes in land mass due to
Continental spreading Rising ocean levels
Formed about 300 million years ago and still forming!
Andes are still forming Pacific Ocean is getting smaller
Florida then and nowFlorida then and now
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