Exam 1 part 2 Flashcards
Study for the first exam
How did the planet form?
The accept hypothesis is the nebula hypothesis, where a cloud called the solar nebula began to contract due to gravity about 5 billion years ago.
How old is the universe?
14 billion years ago
How old is our solar system?
Only 5 billion years old.
What was the nebula like?
It’s believed that it was a flat disk with a protosun/presun in the middle of it, the larger planets formed from rocky substances and the outer planets came from fragments of ice.
How did the structure of the earth form?
The metals sank down to the earth, the molten rock made the three sections of the earth’s interior, the atmosphere evolved from gases that were released from volcanoes.
The the earth a very hot or cool planet in the beginning?
Very hot
Who proposed the first hypothesis on continental drift and when?
Alfred Wegener, 1915
What was the continental drift hypothesis?
That the continents drifted apart to present day positions 200 million years ago
What 4 pieces of evidence was used to support wegner’s hypothesis?
1) Fit of the continents
2) Fossil evidence
3) Rock type and structural similarities
4) Paleocimatic evidence
What were the 3 objections to the continental drift hypothesis?
1) Lack of mechanism for moving continents
2) Wrong suggestion that continents break through ocean crust
3) strong opposition from all areas of the scientific community.
When was the seafloor spreading hypothesis proposed and by who?
1960s, by Harry Hess
How was the seafloor spreading discovered?
Through sonar waves, sound goes down and comes back up to the ship, the longer it takes the deeper the floor.
Where is seafloor generated and where is it destroyed?
Created at the ridges and destroyed by the trenches.
What does the lithosphere consist of?
The crust and the upper mantle
What are the 7 major lithosphere plates?
They are the 7 tectonic plates
In what ways are the tectonic plates always moving?
They are constantly moving and changing in both size and shape.
About how far does a tectonic plate move a year?
About 5 centimeters/2 inches.
What are the three types of plate boundaries?
1) Divergent (Separating, constructive, new material.)
2) Convergent (Smash together, destructive)
3) Transform (Sliding, neither creates or destroys)
Each plate is bounded by?
A combination of the three types of plate boundaries
Is it possible to have new plate boundaries?
Yes, new boundaries can be created in response to changing forces.
When was Pangaea?
200 million years ago.
Where can you find divergent plate boundaries?
Most are located along the crests of ocean ridges.
Where does seafloor spreading occur?
Along the oceanic ridge system.
is there a difference in ridge topography?
There is a difference due to spreading rates.
What controls spreading rates?
Convection
What does ridge do?
Ridge has a sharp rise but a slow convection rate
What does rise do?
Rise has a gradual rise but a fast convection rate
What does a continental rift do?
It splits landmasses into two or more smaller segments along the rift.
What are two examples of continental rifts?
East African rift valleys and the Rhine valley in Northern Europe.
What are convergent plate boundaries?
They are older portions of oceanic plates that are returned to the mantle in destructive plate boundaries
What are the plate boundaries of convergent plate boundaries called?
They are referred to as subduction zones/ocean trenches.
What is the average angle of a subduction zone?
45 degrees
What are the 3 different types of convergent plate boundaries?
1) Oceanic-Continental
2) Oceanic-oceanic
3) Continental-continental
What do the oceanic-continental convergent plate boundaries do?
This is where the denser oceanic plate sinks underneath the continental plate. Along the descending plate magma is generated creating volcanic mountain chains.
What are two examples of volcanic mountain chains?
Andes and Cascades
What do the oceanic-oceanic convergent plate boundaries do?
When one denser/colder oceanic plate sinks underneath another oceanic plate.
Why would once oceanic plate be denser than another oceanic plate?
Because the plate is colder, cold sinks under hot, it’s cold because it’s farther away from it’s ridge/divergent plate boundary
What happens at continental-continental convergent plate boundaries?
Since the less dense continental plate does not subduct underneath the opposing continental plate, they converge and form mountain ranges.
What is an example of a convergent continental-continental plate boundary mountain/mountains?
Mt. Everest. It’s still growing actually.
What do transform boundary plates do?
They slide past each other, neither creating nor destroying, they are usually in breaks of the oceanic crust called fracture zones.
How are hot spots created?
Through mantle plumes that originate deep in the mantle core
Do tectonic plates move in the same direction?
No
How do we measure tectonic plate motion?
Through a global positioning system, GPS. It’s in space.
Do convection cells move at the same rate?
No
Do tectonic plates move at the same rate?
No.
What is the main force that moves the tectonic plates?
Convection cells within the mantle
What are the names of the three forces that drive plate tectonics?
1) Slab pull
2) Ridge push
3) Slab suction
What are the 4 definitions that make up a mineral?
1) Naturally occuring
2) Inorganic solid
3) ordered internal molecular structure
4) Definite chemical structure
What is a rock?
A solid aggregate of minerals
Is water a mineral?
Yes and no. When liquid or gas, it is not a mineral. When solid, yes.
