Ch 2.1-2.2 Test Flashcards
density
mass of a given volume of substance
Do higher temperatures increase or decrease density?
decrease
Earth is ___% water and ____% land
70, 30
The largest deepest ocean
Pacific Ocean
Half the size of the largest ocean, relatively small
Atlantic Ocean
mostly in the Southern Hemisphere
Indian ocean
Permanent layer of sea ice, very small compared to the other oceans
Artic Ocean
Defined as a meeting of currents
Southern/Antarctic Ocean
What are major differences between a sea and a ocean?
- the sea is smaller and shallower than the ocean
- sea is composed of saltwater
- sea is somewhat enclosed by water
- sea is directly connected to world oceans
The deepest depth in the world and oceans?
Mariana Trench
How many feet below sea level is the Mariana trench?
11,022 meters; 36,161 feet
Who were the first two people to dive to the Mariana Trench? What was the name of the submarine they used?
Lt. Don Walsh and Jacques Piccard; Trieste
What year did the first two people dive to the Mariana Trench?
1960
What year did the famous filmmaker James Cameron make his solo dive to the Mariana Trench? What was the name of his submarine
2012; Deepsea Challenger
What is the tallest mountain on Earth from base to top? How many total feet?
Maunakea; 9,632 meters
Where is he Maunakea mountain located?
Hawaii
Which is greater the deepest depth or the tallest mountain?
the deepest depth
marine habit
the natural habitat where marine organisms live.
Why do geological processes have an influence on marine habitats?
geological processes sculpt the shoreline, determine water depth, and create new islands and underwater mountains.
When the young Earth was molten, where did the densest material flow? Where did the lighter materials flow
The densest material flowed toward the center of the planet. Lighter materials flowed to the surface.
Inner core
center of the earth, solid, iron
Outer Core
center of the earth, outer layer of the core, liquid, iron and nickel
mantle
very hot, flows like a liquid, middle of the earth between the core and the crust
crust
outermost layer, thin, ridgid skin
Why do the continents float on the mantle?
Continents float on the mantle because continental crusts are composed of the same low density material
The oceanic crust is composed of
basalt
the continental crust is composed of
granite
Density of oceanic crust
3.0 g/cm^3
Density of continental crust
2.7 g/cm^3
Thickness of oceanic crust
5 km
Thickness of continental crust
20 to 50 km
Geological age of oceanic crust
young
Geological age of continental crust
old
color of oceanic crust
dark
color of continental crust
light
Main materials in Oceanic Crust
iron and magnesium
Main materials in Continental Crust
sodium, potassium, calcium, and aluminim
lithosphere
the rigid outer part of the earth, consisting of the crust and upper mantle.
the lithosphere is found in ___ major plates. These plates are mobile and move.
7
mid ocean ridges
- Mountain ranges of the
deep. Volcanic in origin, only rises above sea
level in a few places (Iceland).
faults
Displacement of a ridge to one side or the other. Earthquakes are common here.
trenches
narrow, steep sided, and
deep. Common in the Pacific basin
What are earthquakes
associated with?
Plate boundaries.
What are volcanoes associated with?
trenches
Age of Ocean Floor(seafloor rock) Core samples:
sediment by the ridge/rises are
younger and thin. By the trenches, the
sediment is older and thick.
Radiometric dating:
land rocks old and ocean
rocks relatively new.
The age of seafloor rock and the layer of sediment, both ___ (increase, decrease) the farther distance from the ridge
increase
Lava and magma are high in ______
magnetite
What is thought to be the cause of
the magnetic reversals?
Changes in the motion of material in the ironrich outer core of the Earth
How are the magnetic striped
formed?
These magnetic particles will align in a direction parallel to the existing magnetic field at the time since they are fluid and have movement. Then at a certain temperature(~580 °C) they become “frozen” in that particular position; not changing their
direction.
Basalt
the rock type of oceanic crust
has very high concentrations of magnetite.
Each time the earth reversed its magnetic field, it was recorded in the _____ (0ceanic, continental) crust.
oceanic
- Rifts –
– large cracks in the seafloor caused by
the separation of ocean crust. Occurs at midoceans ridges
- What is sea-floor spreading?
Lateral movement of oceanic lithosphere. New seafloor is created here.
How does sea-floor spreading work?
Magma reaches the surface at a spreading center (rift valley, center of the ridge/rise), cools and solidifies to become new crust.
* Crust moves laterally as the lithosphere is carried on the low-density molten material of
the asthenosphere.
* Eventually this crust is recycled back into the mantle at a trench location.
Spreading center
ridges are also called
spreading centers.
What are the “plates” of plate tectonics composed of?
Lithosphere
What is the asthenosphere?
The “plastic”
layer of the mantle. Denser and has a fluid-like
behavior.
How does plate separation
occur?
Through convection cells
Convection Cells:
Currents of low-density
molten material (magma) in
the asthenosphere rising up
to the lithosphere, running
along underneath it, then
cooling and sinking back
down.
How fast do plates separate?
2 to 18 cm per year, depending on location.
Where is old lithosphere destroyed, or “recycled”
back to the mantel?
At deep-ocean trenches
Why do earthquakes and volcanoes form at these
locations?
Large slabs of lithosphere are colliding, with one sinking
below another. This movement causes earthquakes and as the
sinking plate begins to melt in the much hotter mantle, the
molten material, which is less dense, rises to form volcanoes on
the Earth’s surface.
What two types of plate collisions can produce a trench?
Oceanic to oceanic & oceanic to continental
Why does an oceanic plate always subduct beneath a continental
plate?
It is more dense; basalt(oceanic) is denser that granite(continental).
Why is continental rock so much older than oceanic?
Due to it being less dense than oceanic, it does not get recycled back
into the mantel.
What forms when an oceanic plate subducts beneath a continental
plate?
Trenches and volcanic continental arcs(volcanic mountain ranges that
form on the continental plate).
What forms when an oceanic
plate subducts beneath another
oceanic plate?
Trenches and volcanic island
arcs(a system of volcanic island
that forms above the nonsubducting plate).
* Ex. Islands arcs systems such as
the Aleutian Islands or the
Philippines.
Which plate subducts in oceanic
to oceanic?
The older plate. Higher density
due to a longer accumulation of
sediment.
Why is a trench NOT formed when two
continental plates collide?
Neither plate subducts due to
similar densities.
What geological feature is formed when two continetal plates collide?
Uplifting of a mountain range is
created. Crust rises.
Can two continental plates collision form a volcano?
No, no subduction
Describe a shear/transform boundary
Transform boundaries occur
when there is a horizontal
sliding along two plate
boundaries.
How do shear/transform boundary differ from separating and
colliding boundaries?
Material is neither created(as at
divergent, separating boundaries)
or destroyed(as at colliding
boundaries)
Are transform/shear boundaries found in oceans?
Transform plate boundaries are
also found in the oceans. They
divide mid-ocean ridges into
segments.
Why do earthquakes occur at shear
boundaries?
Earthquakes caused by the
plates sliding past each other.
What type of boundary is the least intense earthquake?
divergent
What type of boundary is the most intense earthquake?
– convergent boundaries where subduction occurs and sometimes transform/shear
Slab Pull Theory
Plates separate at mid-ocean ridges. Magma rises at these ridges,
cools becoming denser. Eventually this cold, dense lithosphere sinks
back into the mantle, pulling the slab of lithosphere
The western coast of North America is a classic example of ______.
transform/shear boundary
Which distinctive feature is found at a subduction zone?
ocean trenches, volcanos, and mountains
The transform plate boundary divides two plates that are moving in the ______ direction
opposite
oceanic to continental creates
trenches, volcanic mountain ranges
oceanic to oceanic creates
trenches and volcanic islands
continental to continental creates
mountain ranges
