Continental Drift and Sea-Floor Spreading Flashcard

Front

What is continental drift?

Back

A hypothesis about the movement of continents

Answer explanation

Continental drift is a hypothesis that explains how continents move over geological time. It contrasts with the other options, which focus on ocean currents, mountain formation, or weather patterns.

Front

Who proposed the hypothesis of continental drift?

Back

Alfred Wegener

Answer explanation

The hypothesis of continental drift was proposed by Alfred Wegener in the early 20th century. He suggested that continents were once joined and have since drifted apart, a concept that laid the groundwork for modern plate tectonics.

Front

What was the name of the single landmass mentioned in the continental drift hypothesis?

Back

Pangaea

Answer explanation

The single landmass referred to in the continental drift hypothesis is called Pangaea. It existed during the late Paleozoic and early Mesozoic eras before breaking apart into the continents we know today.

Front

What is sea-floor spreading?

Back

The rise of molten rock at mid-ocean ridges

Answer explanation

Sea-floor spreading refers to the rise of molten rock at mid-ocean ridges, where new oceanic crust is formed as tectonic plates move apart. This process is crucial for understanding plate tectonics and ocean floor formation.

Front

What forms as a result of sea-floor spreading?

Back

New oceanic crust

Answer explanation

Sea-floor spreading occurs at mid-ocean ridges where tectonic plates pull apart, allowing magma to rise and solidify, forming new oceanic crust. This process is essential for the creation of new ocean floor.

Front

What creates a pattern of symmetrical stripes on either side of the mid-ocean ridge?

Back

Magnetic reversals

Answer explanation

Magnetic reversals create symmetrical stripes on either side of the mid-ocean ridge as new oceanic crust forms and records the Earth's magnetic field changes, resulting in a distinct pattern.

Front

What happens to magnetic minerals as magma cools at mid-ocean ridges?

Back

They align with Earth's magnetic field

Answer explanation

As magma cools at mid-ocean ridges, magnetic minerals align with Earth's magnetic field. This alignment occurs because the minerals become magnetized in the direction of the magnetic field, preserving a record of it.

Front

What is preserved in rocks as a result of magnetic minerals aligning with Earth's magnetic field?

Back

A record of Earth's magnetic polarity

Answer explanation

Magnetic minerals in rocks align with Earth's magnetic field, preserving a record of Earth's magnetic polarity. This alignment occurs during the cooling of magma or sedimentation, capturing the direction of the magnetic field at that time.

Front

What forms when Earth's magnetic field reverses during sea-floor spreading?

Back

New stripes of crust with opposite magnetic polarity

Answer explanation

During sea-floor spreading, when Earth's magnetic field reverses, new stripes of crust form with opposite magnetic polarity. This occurs as magma solidifies at mid-ocean ridges, capturing the current magnetic orientation.

Front

What pattern is created by alternating magnetic stripes?

Back

Parallel to the mid-ocean ridge

Answer explanation

The pattern of alternating magnetic stripes is created as new oceanic crust forms at the mid-ocean ridge, resulting in stripes that are parallel to the ridge due to the Earth's magnetic field reversing over time.