Earth's Layers and Structure
What is Earth’s outer layer made of beneath both land and ocean?
Hard, solid rock (crust)
What happens when two plates move apart?
New rock forms as magma rises and hardens.
What is the theory that explains why continents move?
Plate Tectonics
Where do most volcanoes and earthquakes occur?
Along plate boundaries
What tool helps scientists track plate movement today?
GPS satellites
What are the two main types of crust called?
Continental and oceanic crust
What happens when two plates move toward each other?
One plate goes under the other or mountains form.
What did scientists notice about fossils on different continents?
Same species found on continents now far apart
What pattern do volcano and earthquake maps show?
They occur in similar areas (the “Ring of Fire”)
How fast do Earth’s plates move on average each year?
A few centimeters per year (2-3cm per year)
What lies directly below the crust?
The mantle
What is the name of the process where one plate goes under another?
Subduction
What ancient reptile’s fossils were found in both Africa and South America?
Mesosaurus
What causes an earthquake?
The sudden release of energy as plates move or slip
Why does it take millions of years for continents to move noticeable distances?
Because plate motion is very slow.
Why is the mantle described as “soft, solid rock”?
It flows slowly over time, allowing plates to move.
What type of boundary creates new ocean floor?
Divergent boundary
How do fossils help prove continental drift?
They show continents were once connected.
What happens to rock when it melts beneath the crust?
It becomes magma, which can rise to form volcanoes.
What is a cross section, and why do scientists use it?
A vertical cut that shows inside layers of Earth. Scientists use these visuals to help explain what is happening between Earth's layers.
How do scientists know about Earth’s internal layers without seeing them directly?
By studying seismic (earthquake) waves.
At a convergent boundary between two continental plates, what feature is likely to form?
Mountain ranges (e.g., the Himalayas)
Why can’t fossils of land animals be explained by swimming across oceans?
They lived on land and couldn’t cross vast oceans, proving plates moved.
How do volcanic eruptions and earthquakes provide clues about plate movement?
They show where plates are colliding, separating, or sliding past each other.
How do scientists use rock formations to support plate movement?
Matching formations across continents show they were once connected.