midterm part 1 Flashcards
list the different stages of wilson’s cycle with examples
Stage 1: Embryonic - East African Rift Valley
Stage 2: Juvenile - Red Sea
Stage 3: Mature - Atlantic & Arctic Ocean
Stage 4: Declining - Pacific Ocean
Stage 5: Terminal - Mediterranean Sea
Stage 6: Suturing - Himalayas
What is a rift valley?
formed by the interaction of earth’s tectonic plates
Magma rises into the crustal fractures forming rift valley
What are the types of convergent boundaries between crusts?
- Ocean / continent convergence: the oceanic plate subducts
- Ocean / ocean convergence: the older cooler denser plate subducts
- Continent / continent convergence: Both uplift
What are the differences between continental and oceanic crust?
- The continental crust is made mostly of rocks with a composition similar to granite
- The oceanic crust is made mostly of rocks with a composition of basalt
What is earth’s chemical layer made up of?
crust -> upper mantle -> transition zone -> lower mantle -> outer core -> inner core.
- Oceanic crust: (Basalt: Oxygen, silicon, magnesium and iron) - Continental crust: (Granite: Oxygen, silicon and aluminium) - Mantle (Oxygen, iron, magnesium and silicon) 68% Earth´s mass – 83 % Earth´s volume - Core (Iron and nickel)
What is earth’s physical layer made up of?
Lithosphere -> Asthenosphere -> Mesosphere -> Fluid -> Solid
- lithosphere (rigid),
- asthenosphere (melted, flowing),
- lower mantle (not melted, slow flow),
- outercore (viscous liquid)
- inner core (solid).
In which direction does the core of the Earth rotates?
inner: eastward
outer: westward
What are mantle plumes?
Continent-sized columns of superheated mantle
What is currently lifting all of Africa, fracturing the center of the continent?
A superplume
How is a line of islands formed?
Hot spots form straight chains of volcanoes and volcanic islands (Hawaii)
Explain the tectonic plates theory
suggests that Earth´s
surface is not static.
The theory states that the Earth’s solid outer crust, the lithosphere, is separated into plates that move over the asthenosphere, the molten upper portion of the mantle. Oceanic and continental plates come together, spread apart, and interact at boundaries all over the planet
Explain the seafloor spreading theory
a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge
Explain the continental drift theory
Was proposed by Alfred Wegener (1912)
• States that originally there was a single
supercontinent: Pangaea, surrounded by an
ocean called Panthalassa
• And that Pangea was broken into pieces 200 million years ago and pieces are still moving
Which one is denser the continental or the oceanic crust?
oceanic
What is paleomagnetism?
When magma forms oceanic plates, magnetite aligns with Earth´s magnetic
field and “freezes”
when rocks solidify “capturing” the magnetic field orientation of Earth in
that moment
What protects the earth from radiation? and how does the Earth have a magnetic field?
Rotation of the metallic core produces a magnetic field.
The magnetic field of the Earth protect us from radiation
caused by the movement of molten
metal in outer core
what are Terranes?
buoyant plateaus,
isolated segments of seafloor,
ocean ridges,
ancient island arcs,
and parts of continental crust squeezed into continent face when the plate is subducted
What are the types of plumes?
Mantle plumes = Continent-sized columns of superheated mantle
• A Superplume is now lifting all of Africa, fracturing the center of the
continent (i.e. East African Rift)
• Hot spots = Surface expressions of plumes rising from stationary sources of
heat in the mantle
What are the different steps of the scientific method?
observation, question, hypothesis, test, analysis, conclusion
What percentage of Earth´s surface water is salty?
97.5
How old is the Earth?
4.5 billion yrs
What protects the earth from radiation?
Rotation of the metallic core produces a magnetic field. The magnetic
field of the Earth protect us from radiation
Why are stars relevant to the formation of the ocean?
Most of Earth’s, sea and human beings atoms were formed within stars billions of years
ago
What percent of the earth’s surface is covered by water?
71% of Earth’s surface is covered by water
How did the oceans become salty?
Water vapor formed clouds and rain dissolved minerals, accumulating salty water
What is the name of the oldest Fossils and where can they be found?
Stromatolites, Australia
What is a supernova?
A supernova is a powerful and luminous stellar explosion. a dying star.
What is the big bang theory? How do we explain the origin of the universe?
Galaxies and stars formed in nebulae
Sun and planets condensed from dust and gas from supernova
What is outgassing?
Second atmosphere formed by outgassing: water vapor and other gases from volcanic venting
What are guyots?
flat-topped seamounts
What is the depth of the mariana trench?
11 km deep, 70 km wide, 2550 km long
What are sea mounts?
conical projections higher than 1 km
How are oceanic trenches formed?
by subduction of lithosphere at converging plate boundaries
True or False? the further away you are from the origin center the
colder and denser the crust is
true
How many people travel to the bottom of the ocean (Mariana´s
Trench)?
10
what is the ocean basin
deep seafloor beyond the continental margin
Ocean basins form at divergent
plate boundaries
how is the ocean floor mapped?
by bathymetry: weighted line, echo sounder, multibeam echo sounder systems and
satellite altimetry
What is a continental margin?
submerged outer edge of a continent. 3 main divisions:
- Continental shelf: nearly flat, close to shore
- Continental slope: more steeply sloped, seaward
- Continental rise blends continental margins into deep ocean basin
What are passive and active cont. margins?
- Passive continental margins: face the edges of diverging plates, little volcanic or earthquake activity
- Active continental margins: near the edges of converging plates, ongoing earthquake and volcanic activity
What are continental shelves?
7.4 % Earth´s ocean area. Part of granitic continental crust.
Influenced by changes in sea level
what is the deep ocean floor?
oceanic ridges + adjacent sediment plains (50 % Earth´s surface)
ocean ridges
In average 2 km high.
Projected above: Iceland, Azores or Easter island.
Not straight - transform faults
abyssal planes
featureless expanses of sediments - hide irregularities in underlying oceanic crust
abyssal hills
Less than 200 m high, hills bordering oceanic ridges
Trench
arc-shaped depression in the deep-ocean floor.
Island arcs
Curving chains of volcanic islands and seamounts, parallel to concave edges of trenches
submarine slopes
Submarine canyons cut into the Continental shelf and slope
• Sometimes deeper than 3000 m
• Caused by landslides or sediments liquefaction (triggered by earthquakes)
Turbidity currents
Underwater abrasive “avalanches” of
sediments.
hypothermal vents
hot springs in oceanic ridges, Water 350 ºC water descends through fissures, superheated water dissolve minerals and gases and escape through the vents
How does the process of studying sediment layers work?
through the study of the ocean’s past
What are neritic sediments?
On continental margins. Can form sedimentary rocks by Lithification
Examples of Oozes?
Ooze is deep ocean sediment with at least 30% biogenous material.
Can be siliceous or
calcareous -
What does paleoceanography study?
study of the ocean’s past
What percent of the seabed is covered by calcareous ooze? What
percent is covered by siliceous ooze?
cal 48
sil 14
Define pelagic sediments
Slope, rise, and deep-ocean floors
What is the process of lithification?
It refers to the process that loose and underconsolidated Sediment particles transform into hard and solid rocks.
Define marine sediments
usually combinations of terrigenous
and biogenous deposits
How are sediments usually classified?
sediments are classified by source, they are Particles of organic or inorganic matter that accumulate in a loose, unconsolidated form
Originate from the weathering and erosion of rocks, living organisms,
volcanos, water chemical precipitation or from space
types of sediments
Terrigenous sediments
• Biogenous sediments
• Hydrogenous sediments
• Cosmogenous sediments come from space
what is a subduction zone?
(Earth is not growing up)
• Creation of new crust balanced by destruction of crust
types of plate boundaries?
-Divergent boundary: two plates move apart from each other
• Convergent boundary: two plates move toward each other and interact
• Transform or transverse boundary: two plates slide laterally past each other
what is the main heat source inside earth?
Radioactive decay
How does heat move towards surface
conduction and convection
what is buoyancy
Ability of an object to float in a fluid by displacing a fluid volume equal in weight to the floating object’s weight
what is isostatic equilibrium?
the state of gravitational equilibrium between the earth’s lithosphere and asthenosphere
such that tectonic plates float at an elevation which depends on their thickness and density
conduction
the process by which heat is transferred through objects by contact, heat energy passes from warmer to cooler object.
convection
heat moves within fluid - heat transferred from warmer to cooler areas through fluid
