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1) What does the Nebula Hypothesis explain?
- Most of the Earth's substances and
- that of the ocean were formed by stars. Stars form in nebulae-large, diffuse
- clouds of dust and gas within galaxies. The condensation theory is based on
- this inference and explains how stars and planets are believed to be formed.
- A model of star and planet formation in which a nebula
- contracts under the force of gravity, eventually flattening into a spinning
- disk with a central bulge. A protostar forms at the nebula's center. As matter
- condenses around the protostar in the bulge, planets are formed from the
- spinning matter in the disk. This theory is widely accepted to account for the
- formation of stars and planetary systems such as ours. The first version of the
- nebular hypothesis was proposed in 1755 by the German philosopher Immanuel Kant
- and modified in 1796 by Pierre Laplace. The nebula that
- according to this hypothesis condensed to form the solar system is called
- thesolar nebula
How does differentiation relate to the formation of our solar system?
Differentiation relates to the formation of our solar system because denser objects were pulled closer to the center of the protostar, creating planets.
How does differentiation relate to the formation of the layers of our Earth?
Denser parts of the Earth are at the center of the planet, where the less dense parts are at the surface.
When do we see the first evidence for water on Earth?
3.9*109 yrs ago
What is the evidence of water on Earth?
Evidence = Sedimentary rocks that formed by processes requiring water are about 3.9 billion years old
What are the two possible sources of water on Earth?
Water is released through volcanic activity, water vapor (from the hydrogen and oxygen).
Is the Earth a perfect sphere?
No, it is an Oblate Spheroid.
What is latitude?
Latitude, how tall the earth is, the reference is the equator.
What is longitude?
How wide the earth is, the reference is the prime meridian.
Where is most of the water on Earth and what is its distribution?
The most water is in the oceans and sea ice and it is approximately 97.26% of the water.
What was some of the early evidence provided
that suggested that all of the continents once formed one large landmass?
Geological and paleontologic and climatologic evidence: shorelines of continents fit togehter, mountain ranges fit, marine and plant fossils matched
Why is plate tectonics call a unifying theory?
It helps explain: earthquakes, volcanic eruptions, formation of mountains, location of continents, location of ocean basins
It influences: atmospheric and oceanic circulation, and climate, geographic distribution, evolution and extinction of organisms
How do the reversals of Earths’ magnetic field help prove the sea-floor spreading
The magnetic anomalies were discovered to be striped, parallel to the oceanic ridges. Measuring paleomagnetism and dating continental lava flows lead to the realization that magnetic reversals existed and the establishment of a magnetic reversal time scale.
How do radiometric dates of the seafloor help prove the sea-floor spreading
Seafloor spreading theory indicates that oceanic crust is geologically young and is destroyed during subduction. Radiometric dating confirms the youth of the oceanic crust, youngest occurs at mid-ocean ridges, and the oldest is 180 million – up against continent, oldest continental crust is 4.28 billion yeas old
Where is the longest mountain system on Earth located?
The Mid-Atlantic Ocean Ridge
Know the three main types of plate boundaries.
- Transform-Fault: they scrape
- against one another
- Convergent: they collide,
- subvergent happens here
Divergent: they move apart
Know the three types of convergent plate
- Oceanic-Continental: Oceanic Plate
- gets submerged under continent and mountain ranges form
- Oceanic-Oceanic: One side usually
- subducts and creates a trench
- Continental-Continental: The two
- collide and move upward because they are so light, creating a mountain range
Where is continental rifting occurring today?
The mid-Atlantic ridge
What is Japan? Why is it there?
Japan is there as a result of convergent boundaries coming together and rising above the water.
How did the Himalayas and the Tibetan Plateau form?
They formed because they are on the boarder of converging plates that came together.
If you found an ophiolite sequence is Rhode
Island what would you conclude?
I would conclude that Rhode Island was at one point a subduction zone.
How did the Hawaiian Islands form?
On convergent boundaries, sometimes there are hotspots that create volcanoes, Hawaii is the result of volcanic eruptions.
What are the main mechanisms for plate tectonics?
Convection cell movement, where the layers of the earth move around due to the heat.
How do the Atlantic and Pacific coasts of North America differ?
The Atlantic is near a diverging convergent plate, where the Pacific coast is on a transform boundary.
Continental Shelf definition:
The area of seabed around a large landmass where the sea is relatively shallow compared with the open ocean.
Shelf Break definition:
The slope where the continental shelf ends and it becomes deep ocean (where the continental slope begins).
Continental Slope definition:
The slope between the outer edge of the continental shelf and the deep ocean floor
Continental Rise definition:
A wide, gentle incline from an ocean bottom to a continental slope. A continental rise consists mainly of silts, muds, and sand, and can be several hundreds of miles wide. Although it usually has a smooth surface, it is sometimes crosscut by submarine canyons.
Are wide continental shelves most often found on active or passive continental
Passive, because there is no plate boundary there to make it so deep.
What forms the continental rise?
Turbidity currents and underwater landslides.
What are turbidity currents?
An underwater current flowing swiftly ownslope owing to the weight of sediment it carries.
How does a drowned river valley form?
Coastel inlet formed by partial submergence of a glacier.
Ocean basins are separated by what?
Mid ocean ridges and rises.
What are abyssal hills and guyots?
- Abyssal hills are small sediment covered extinct volcanoes. They are the most abundant geomorphic feature on the surface of the Earth.
- A guyot is an isolated underwater volcanic mountain (seamount), with a flat top and is below the surface of the sea.
How does a coral atoll form?
An atoll is formed first as a reef that fringes a volcanic island. As the island sinks (after the volcanic activity has ceased and the crust has cooled, becoming denser), the reef continues to build upward, eventually ending up as a ring-shaped structure.
Where do the slowest rates of sedimentation in the oceans occur? Why?
The ocean basins, because they are older.
Where do the fastest rates of sedimentation in
the oceans occur? Why?
The continental margin, because it is less dense.
pre-existing rock; forms coral
all land derived material; sand, mud, and silt
living organisms; cocolithophorids, pteropods, foraminifera dominant pelagic sediment
precipitation from sea water
Why are carbonate sediments rare beyond a depth of 4500m in the ocean?
CCD: dissolution equals accumulation 4500m