Physical Geography Flashcards
Physical geography is the study of what?
Processes and patterns in the natural environment.
How far do the continents move each year?
A few centimeters.
Who first suggested that the continents were moving?
German climatologist and geophysicist Alfred Wegener
What was his theory?
Once all the continents were part of a super continent, caused by continental drift.
What is the super continent called?
Pangaea
How long ago did the super continent exist?
300 million years ago before breaking up.
What proof is there of continental drift?
- Fossils of the same creatures are found on different continents, separated by oceans.
- South America and Africa fit together like a puzzle.
- Similar mountains are found on both sides of the Atlantic.
- Ice sheets once covered now tropical places.
What is the difference between continental drift and plate tectonics?
Wegener said only the continents were moving. Plate tectonics says that plates consist of both Oceanic and Continental crust.
What is earth’s crust called?
The lithosphere.
What is the lithosphere?
Earth’s crust.
What is the lithosphere moving over?
The asthenosphere.
What is the asthenosphere?
A layer of hot rock within the mantle.
The earth can be divided into 4 layers. Name them.
- Crust
- Mantle
- Outer core
- Inner core
How many tectonic plates are there?
Around 20.
What causes the lithosphere to move?
Convection currents.
What are convection currents?
Heated fluid (hot rock within the earth) rises, carrying heat to the surface, only to cool, sink, and be reheated.
What is a divergent plate boundary?
Where two plates are moving away from each other.
What is a convergent plate boundary?
When plates are moving toward each other.
What is a transform plate boundary?
When plates are sliding against each other in opposite directions.
Which are heavier: Oceanic or continental plates?
Oceanic plates.
What is a subduction zone?
When a heavier plate dives under a lighter one.
Where do most volcanoes occur?
Parallel and inland to subduction zones.
Where do most earthquakes occur?
Along transversal plate boundaries and subduction zones.
Why do earthquakes occur?
When plates move along each other, they build up friction. When the are jammed, eventually something will give. The friction will be released, causing an earthquake.
What is it called when two plates are moving away from each other?
Divergent plate boundary.
What is it called when plates are moving towards each other?
Convergent plate boundary.
What is it called when plates move in opposite directions to one another?
Transform plate boundary.
What is it called when one plate goes under another?
Subduction zone.
What is folding?
The bending of earth’s crust.
What is faulting?
The cracking of earth’s crust.
How are mountains built?
Folding, faulting, and volcanic activity.
What are rifts and how are they caused?
The earth’s crust is pulled apart.
What is extension?
The pulling apart of earth’s crust.
Name a famous rift.
The Great Rift Valley in Africa.
What are convection currents?
Heated fluid (hot rock within the earth) rises, carrying heat to the surface, only to cool, sink, and be reheated.
Why can’t we travel to the center of the earth?
- Pressure
2. Heat
Is there more water above earth’s crust or below it?
Below.
As you get closer to earth’s core, what happens to gravity?
It becomes stronger.
What does gravity do?
Prevents earth’s atmosphere from floating away.
What happens to air as you get closer to the earth’s surface?
It becomes more dense.
How thick is the lithosphere?
30 miles.
How far can rivers flow in caves?
Hundred of miles.
What are the remnants of ancient underground lakes, found in caves?
Giant crystals.
The Alps are made of what?
A piece of Africa sitting on Europe.
What is the Midatlantic Ridge?
A divergent plate boundary causes magma to seep up, creating a ridge.
How far does the Midatlantic Ridge stretch?
From the middle of the Atlantic onto Iceland.
What is magma?
Molten rock beneath earth’s crust.
What is lava?
Molten rock that has reached the surface.
Describe the conditions of Pangaea.
Vast swamps and rainforests, flat, well watered.
How much oxygen was is the atmosphere around the time of Pangaea?
There was 60% more oxygen.
An increase in oxygen leads to what?
Super sized animals.
How far down is the deepest mine?
2.5 miles
How long does it take to go down the longest mine elevators?
2 hours
What is the deepest hole ever dug?
7.5 miles
What kind of life is found below earth’s crust?
Bacteria.
What is needed for extremifiles to survive?
Rock, water, and heat.
How far down can life be found?
10 km.
What started a biological revolution, and what did it allow?
Oxygen allowed complex life to exist.
What makes the oceans blue?
Iron oxide.
What changes solid mantle rock into lava?
A change in pressure.
What is the land between the crust and the mantle called?
The moho.
How heavy is mantle rock compared to granite?
Twice the weight of granite.
Mantle is rich in what?
Heavy elements and gemstones.
Why are gemstones found in the mantle?
They form under extreme pressures.
Why is the mantle crucial for life?
It causes the continents on top of it to move.
What are diamonds and how are they made?
Crushed carbon formed by volcanic eruptions billions of years ago.
What are flaws in diamonds?
Primitive pieces of mantle.
How do geologists measure earthquakes?
With seismometers..
What do seismometers do?
They determine the difference between layers of the earth.
If all earth’s water was above the crust, what would the land look like?
There would be no land.
Where is the Ring of Fire?
It circles the Pacific Ocean.
How large are plumes within the mantle in diameter?
100 miles.
What can mantle plumes create?
Islands.
What does the earth’s magnetic field do?
Protects life from radiation.
What would happen to the magnetic field if the earth stopped spinning?
It would disappear.
Is earth’s magnetic field getting weaker of stronger?
Weaker.
Where is the earth’s magnetic field the weakest?
The South Atlantic Anomaly.
What would happen if the earth’s magnetic field reversed?
We would lose our shield for several months.
What is the inner core made of?
Solid metal.
By how much does the inner core expand every year?
1 m
How hot is the earth’s core compared to the surface of the sun?
It is hotter than the sun.
How was the core created?
Heavy iron sunk down.
Meteorites can tell us what? Why?
They can give a glimpse of earth’s core as they are rich in iron.
