Sea-Floor Spreading & Rock Ages
The youngest oceanic rocks or oceanic crust are found in this location.
A mid-ocean ridge
This type of boundary causes earthquakes
Transform
This scientist proposed continental drift.
Alfred Wegner
The Hawaiian Islands formed because of which geologic feature?
Hotspots
This landform commonly forms at continental convergence.
Mountains
This process creates new oceanic crust as plates move apart.
Seafloor spreading
This plate boundary forms when two continental plates collide and push upward.
Convergent
This law helps scientists determine the relative age of rock layers.
The Law of Superposition
Why don’t hotspot volcanoes form at plate boundaries?
hey form from mantle plumes beneath moving plates, not from plate interactions.
This landform forms at divergent boundaries in the ocean.
A mid-ocean ridge
As you move farther away from a mid-ocean ridge, the oceanic rocks become _____.
older
The Mid-Atlantic Ridge is an example of this type of plate boundary.
Divergent
This scientist proposed the idea of sea-floor spreading.
Harry Hess?
Supervolcanoes usually form when large amounts of magma collect beneath the Earth’s crust and erupt from this type of feature.
hotspot or magma chamber
Match the boundary to the landform:
• Trenches → _____
• Fault lines → _____
• Ridges → _____
Convergent, Transform, Divergent
Why are oceanic rocks near mid-ocean ridges younger than rocks farther away?
New magma rises and hardens at the ridge, pushing older rock outward.
An oceanic plate sinks beneath a continental plate, forming volcanoes and trenches. Identify the boundary type.
Convergent with subduction
Harry Hess suggested that new ocean crust forms at what land form?
Mid-ocean ridges
Why are supervolcano eruptions more dangerous than most volcanic eruptions?
They release extremely large amounts of ash, gas, and magma that can affect climate and ecosystems.
Why do convergent boundaries often have volcanoes?
Because subducting plates melt and magma rises to the surface.
Explain how the ages of sea-floor rocks provide evidence that tectonic plates move.
Younger rocks are near ridges and older rocks are farther away, showing the sea floor spreads as plates move.
Use fossil, rock, and landform evidence to explain plate tectonics.
Answers vary
Explain how sea-floor spreading supports the theory of plate tectonics.
New crust forms at ridges and pushes older crust away, showing plates move.
Compare how volcanoes form at hotspots versus convergent boundaries.
Hotspots form from rising mantle magma, while convergent volcanoes form from subduction.
Name TWO different landforms and explain which plate boundary forms each.
Answers vary