Sea-Floor Spreading

___________ is the hypothesis that states that the continents were once a single landmass, then broke apart and drifted to their current locations.

• Continental Drift

• Seafloor Spreading

• Plate Tectonics

• Mid-Ocean Ridge

_______ are mountain ranges at the bottom of the ocean.

• Seafloor hills

• Mid-ocean ridges

• Tectonic plates

• Photosynthesis

In seafloor spreading, molten material from the mantle rises and erupts

• along the edges of all continents

• along mid-ocean ridges

• in deep ocean trenches

• at the North and South Poles

The oceanic crust near the mid-ocean ridge is younger than the oceanic crust farther from the ridge.

• True

• False

___________ is the process through which

new oceanic lithosphere (seafloor) is formed as magma rises to the Earth's surface and solidifies at the mid-ocean ridge.

• Continental drift

• Seafloor spreading

• Plate tectonics

• Mid-ocean ridge

The mid-ocean ridges are sites of intense _________ activity.

• emotional

• volcanic

• seismic

• athletic

The mid-ocean ridges form the longest mountain ranges on Earth.

• True

• False

What technology did scientists use in the mid-20th century to map the mid-ocean ridge?

• Satellites

• Deep-sea diving

• Submarines

• Sonar

At the mid-ocean ridge, molten rock rises through the cracks in _________.

• the ceiling

• the river

• the inner core

• the seafloor

Most geologists believe that the movement of Earth's plates is caused by __________________.

• conduction

• earthquakes

• convection currents in the mantle

• Earth's magnetic field