UNIT 3 Guided Notes Marine Geology
Marine Geology
• Study of the _________________and ___________________ of our
planet’s seafloor and continents and the _______________________
• How did the oceans and continents form?
•
Big Bang
• 20 billion years ago
• Matter (all elements in periodic table) expanded into space
• Matter clumped and planets formed 5 bya
• Early on our planet is a hard rock being _________________________
______________bodies and experiencing _______________________
Formation of the Earth’s Layers
1. Heating (leftover radioactive heating)
_____________ (Fe and Ni) material _____________to the center
_____________(Si and O) material ____________ to surface
Some materials __________ to form early _________ and __________
2. Layers formed
3. Planet cools
Our “usual” image of Earth
Evidence for layers from _____________________
Early Atmosphere
• 3.5 bya
• Water vapor, carbon monoxide, hydrogen sulfide, nitrogen and cyanide
Early Oceans
• 4 bya water vapor from mantle is cooled and collects on surface.
• 1000’s of years of thunderstorms and rain
• Low lying spots fill to become our early oceans
• Water also from _______________________________________
____________________________________________________
Origin of the Continents
• _____________________suggested the continents were not always on
their present positions
• _________________________
• 200mys a single landmass called Pangea broke up
• Evidence
– Coastlines fit like a __________________________
– Similar ___________________________ on different continents
Problems with Continental Drift
• ______________________ for how the continents “drift”
• Wegener was a meteorologist…what did he know anyway!!!
Crust
–
–
____________________
• less dense, rocks that floated to the surface when the Earth
was formed
• between 35km and 70km thick.
not a _____________________
• Split into plates, which are free to drift slowly across the
surface of the planet.
Moving Plates
• Continents move 1 cm/yr
• Boundary between plates is a _____________________
– Seismic activity occurs at faults ( ___________, ___________)
• The lower mantle is heated by the core which creates ________________
• Rising magma may break thru the crust at ridges like the
_____________________________________
•
•
___________________- plates move apart from rising magma at a ridge
___________________- two plates collide and the denser plate sinks into
the mantle
– Forms ________________ (ex
)
– Trenches are the deepest parts of the ocean
Ocean Floor Formation
• Sea floor spreading is source of ______________________
• Subduction ______________ ocean flow back into the mantle
• Atlantic is _______________
• Pacific is ________________
Sea Floor Spreading Evidence
• Younger rocks are found __________- to the ridge
• _______________ sediment closer to the ridge
• Polarity of magnetic minerals is mirror image on either side of the ridge
– N and S pole flip periodically
– _______________________ as magma cools with the N pole
Plate Tectonics
• Unifying theory that combines ______________________________
• Explains the origin of, connections between earthquakes, volcanoes,
faults, continental drift and sea floor spreading
• Explains how oceans and its features are formed
Billl Nye Movie Notes
Which of the Earth’s layers produces the Earth’s magnetic field?
Where did the Earth’s original heat come from?
Where does the Earth’s current heat come from?
How did the Earth’s layers form?
Why We Have Oceans & Why The Ocean Floor Is Not Flat
Ocean Floor Topography
• Average ocean depth is 3636 m
• ______________-is used to map features of the ocean floor
• The _______________________________________topography
Oceanic crust is _____________than continental crust sinks _____________into
the mantle
This is why it is ______________________and has become an ocean basin.
Two types of crust
• Continental crust
•
•
•
•
•
• Oceanic Crust
•
•
•
less dense ( lighter)
much older and thicker than oceanic crust.
floats on the mantle (like an iceberg floats in water)
_____________km thick
_________million years old
___________ thick
Younger than __________
Sinks into mantle
Typical Ocean Floor Features
• Continental ___________-extension of the continent
• Continental ____________- steep drop off from shelf and end of the
continent and it’s crust
• Submarine ________________- deep valleys in the slope created by
underwater landslides or old rivers
• Continental __________- a pile of sediment that has slid down the slope
• __________________- Islands created by underwater volcanoes
Plate Tectonics and Continental Coastlines
•
•
Active margins (example-California) sites of ___________________earthquakes, volcanoes, mountains,
– ____________ continental shelf and _________continental slope
ending in trench
Passive (example- NJ)
– Little to no tectonic activity
– ______________ shelf, pile of sediment at the bottom of the slope
Plate Margins
• Converging plates
• Oceanic crust meets Continental crust- oceanic __________ under
continental: trench, and volcanic islands and earthquakes
• Oceanic crust meets oceanic crust- one plate _________under the
other results in trench, islands and earthquakes
• Continental meets continental- _____________
Features of Ocean Ridges
• Water is ________________(371 C) by hot magma and ______________
___________________ from nearby rock
• As water comes out from the rock it looks like smoke
• Area with these hot springs is called a ____________________________
Animals From Hydrothermal Vents
• Bacteria are the base of the food chain
• ___________________- make sugars using energy from compounds like
H2S
• Other vent animals include giant tubeworms, crabs, octopus, shrimp and
mussels
Why are we learning about it?
•
________________________________________________________
•
Impact on human life
•
Better understanding can help us predict future natural disasters
Distribution of the World’s Oceans
•
Cover ______________ of planet
•
Southern hemisphere is ________ocean while Northern hemisphere is only
__________________ocean
•
Separate but connected basins
•
Include features like ______________________________________
•
Most of the ocean bottom is the ______________________(flat and featureless)
The Ocean Bottom
•
Vertical cross section of ocean reveals many features
–
___________________________- closest to beach, gentle slope
–
___________________________- depth increases rapidly
–
___________________________- narrow zone transitioning between slope and flat
ocean bottom
–
All three zones are a part of the_______________________
Continental Margins
•
Includes the ____________________________________________
•
Tectonically active margins have a __________________________
•
Tectonically passive margins have a _________________________
Active Continental Margins
•
Continental slope goes directly into a ______________________
•
Sediments washed from the land spill into the trenches and are “lost”
Passive Continental Margins
•
Continental rise meets with a _______________________________
•
Sediment from the land spreads out over the plain
Plate Tectonics
•
Explains the _____________________________________________
_______________________________________________________
•
The place where the two plates meet is called a plate______________. Boundaries have
different names depending on how the two plates are moving in relationship to each other
–
crashing: ______________________________
–
pulling apart: ___________________________
–
or sideswiping: _________________________
Plate Tectonics Explains
Location of Continents
Mid-ocean Ridges
Mountains
Trenches
Volcanism
Earthquakes
Evidence for Plate Tectonics
1. __________________________________________
•
Frank Taylor (1910)
•
Alfred Wegener (1912) Die Entstehung Der Kontinente Und Ozeane
–
Continents move over the surface of the planet
–
Based on the close fit of continent outlines
–
Couldn’t explain why the plates move
2. _________________________________________________
•
Harry Hess and Robert Dietz (1950’s)
–
Convection currents move the lithospheric plates
–
Sea floor spreading: Two plates ______________(move apart) on the ocean floor
….____________________________________________
–
Subduction: Denser plates ___________________(crashing) sink into the
mantle….___________________
Sea Floor Spreading Evidence
•
Sea floor age __________________ on either side of mid ocean ridges
•
Sediment is ______________________away from mid ocean ridges
•
The magnetic field reversal on one side of the ocean ridge is a mirror image on the other
side