Geoscience Time Scales
Which event usually happens in seconds to minutes: a meteorite impact or the formation of a mountain range?
A meteorite impact.
What is a divergent plate boundary?
A boundary where two tectonic plates move apart.
What was the name of the ancient supercontinent that contained most of Earth's landmasses?
Pangaea
Is petroleum renewable or nonrenewable?
Nonrenewable.
What is a tsunami?
A series of ocean waves caused by a major disturbance, commonly an underwater earthquake.
How long can it take for a mountain range to form?
Thousands to millions of years.
Where does new oceanic crust form?
At mid-ocean ridges.
What is a fossil?
Preserved remains or traces of organisms that lived in the past.
What does it mean if a resource is nonrenewable?
It cannot be replenished quickly enough for humans to use it sustainably on a human time scale.
What type of earthquake is most likely to generate a tsunami?
A large underwater earthquake that suddenly moves the seafloor.
Name one geoscience process that can happen in seconds to minutes.
An earthquake, a landslide, or a meteorite impact.
What happens to magma when it rises at a mid-ocean ridge?
It cools and solidifies to form new oceanic crust.
What are two pieces of evidence that continents were once joined?
Matching fossils on different continents and the shapes of continents fitting together like puzzle pieces.
What happens to Earth's supply of petroleum when people extract it from the ground?
It decreases because petroleum is removed from the deposit.
How can movement of the seafloor create a tsunami?
Sudden movement of the seafloor displaces a large volume of water.
Why does flowing water carving a deep valley usually happen on a long time scale?
Water slowly erodes and removes rock over a long period of time.
Why is oceanic crust farther from a mid-ocean ridge generally older?
New crust forms at the ridge and pushes older crust away.
Glossopteris fossils have been found on several continents separated by oceans. What does this suggest?
The continents were once connected, allowing the plant to grow across the joined landmass.
What conditions help transform buried organic matter into petroleum?
Heat, pressure, and millions of years.
What three things are needed for a tsunami to occur?
Explain the difference between a time scale and a spatial scale in geoscience.
A time scale describes how long a process takes. A spatial scale describes the size of the area affected.
Why are most continental rocks older than oceanic rocks?
Continental crust is less dense and less likely to undergo subduction, while oceanic crust is more readily recycled into the mantle.
How does the shape of South America and Africa support continental drift?
Their coastlines fit together like puzzle pieces, suggesting the continents were once connected.
Complete the three statements: Petroleum is nonrenewable because it cannot be replenished in a human lifetime. Its formation is the result of what, and extracting it does what to Earth's supply?
Its formation results from past geoscience processes, and extraction reduces the amount remaining in a deposit.
Why does every earthquake not cause a tsunami?
Answer: Most earthquakes do not displace enough ocean water. A tsunami usually requires significant movement of the seafloor or another event that displaces a large volume of water.