Dynamic Earth: Charac. of the Seafloor

Which statement explains what happens to older crust during seafloor spreading? It is destroyed at coastlines. It moves under continents. It is destroyed at a mid-ocean ridge. It moves away from a mid-ocean ridge.

It moves away from a mid-ocean ridge.

Which is one piece of evidence of seafloor spreading? fossil material continent material drilled core samples ocean water samples

drilled core samples

Which type of zone is located at a deep-ocean trench? convergent divergent subduction transform

subduction

Which is the first step in the seafloor spreading process? A crack forms in oceanic crust. Volcanoes erupt under the ocean. Molten rock rises up through the crust. Dense plates are subducted under less dense plates.

A crack forms in oceanic crust.

Which statement describes the relationship between seafloor spreading and continental drift? As the seafloor spreading occurs, the continents do not move. As the continents move, they pull the seafloor with them. As the continents move, they create new seafloor at the coast. As the seafloor spreading occurs, the continents move.

As the seafloor spreading occurs, the continents move.

According to Hess's theory, what might happen if the magma under a mid-ocean ridge cools? The magnetic stripes might reverse direction. The deep-ocean trench might become deeper. The crust at the ridge might form more quickly. The plates on either side of the ridge might stop moving.

The plates on either side of the ridge might stop moving.

How does oceanic crust move along mid-ocean ridges? away from dense crust parallel to the ridge away from the ridge under less dense crust

away from the ridge

Hess expanded on Wegener's theory of _____. Pangaea landmass continental drift conveyor belt

continental drift

Which type of material becomes molten rock at subduction zones? light plates heavy plates continental crust new oceanic crust

heavy plates

Which event causes the formation of trenches in Earth's crust? magma rising mantle emerging volcanoes erupting lithosphere colliding

lithosphere colliding

From which location does seafloor spreading originate? mid-ocean ridges edges of continents deep-ocean trenches underwater volcanoes

mid-ocean ridges

Which material rises from cracks in oceanic crust? dense crust molten rock continental crust pillow-shaped rocks

molten rock

Which feature of Earth is created at mid-ocean ridges? new island chain new volcanoes new continents new ocean floor

new ocean floor

What is the orientation of the magnetic stripes of iron contained in rocks that support the idea of seafloor spreading? east and west north and east south and west north and south

north and south

Which best describes all new rocks that form near an oceanic ridge? have striped pattern provide evidence to seafloor spreading made from oceanic crust have iron oriented in different directions

provide evidence to seafloor spreading

When scientists analyzed drilling samples from the Glomar Challenger study, which discovery did they make about rocks in relation to a mid-ocean ridge? Rocks closer to the ridge are newer. Rocks closer to the ridge contain more iron. Rocks farther from the ridge are denser. Rocks farther from the ridge are more jagged.

Rocks closer to the ridge are newer.

How do magnetic stripes of iron in ocean rock provide evidence of seafloor spreading? They show when Earth's poles reversed. They show how the density of the seafloor has changed. They reveal a matching pattern on either side of the ridge. They reveal differences in the mineral composition of newly created rock.

They reveal a matching pattern on either side of the ridge.

Hess proposed the idea that ______ are places where crust is created. mid-ocean ridges continents deep-ocean trenches

mid-ocean ridges

Which concept is described in the theory proposed by Hess? Continents do not move. Cool rock pushes through the crust. Trenches are sites of seafloor spreading. Mid-ocean ridges are sites of seafloor spreading.

Mid-ocean ridges are sites of seafloor spreading.

By which mechanism does older oceanic rock move at a ridge? Magnetic forces move the rock. Continents drift and move the rock. The ridge subducts and moves the rock. New molten material rises and moves the rock.

New molten material rises and moves the rock.

Which statement describes the cyclic nature of seafloor spreading? Continents are created. New oceanic crust is created. Volcanoes erupt and remove crust. Old crust gets thicker at subduction zones.

New oceanic crust is created.

Which evidence originally supported Hess's idea of seafloor spreading in 1968? Younger rocks are closer to mid-ocean ridges. The destruction of crust occurs at deep-sea trenches. Oceanic rocks are pillow-shaped when formed. Rocks across the ocean floor have alternating magnetic stripes.

Younger rocks are closer to mid-ocean ridges.

Which discovery did scientists make at mid-ocean ridges that caused them to conclude that new rock was being formed by molten material? magnetic banding pillow-shaped rocks older rocks farther from the ridge rocks with similar characteristics

pillow-shaped rocks

According to the theory proposed by Harry Hess, what causes continents to move? continental drift magnetic polarity seafloor spreading deep-ocean trenches

seafloor spreading

What is the first step of seafloor spreading? A crack forms in oceanic crust. Molten rock rises up through oceanic crust. Molten rock solidifies at the center of the ridge. New material pushes older rock away from the ridge.

A crack forms in oceanic crust.

Which statement describes one event that happens at deep-ocean trenches? Crust is formed. Mountains are formed. Seafloor spreading occurs. Denser plates slide under lighter plates.

Denser plates slide under lighter plates.

How does Earth's magnetic field provide evidence for seafloor spreading? - It creates a pattern of alternating rock stripes on both sides of a mid-ocean ridge. - It allows scientists to determine the age of drilling samples. - It causes magma to harden quickly underwater. - It shows that younger rocks are located deeper underwater than older rocks.

It creates a pattern of alternating rock stripes on both sides of a mid-ocean ridge.

Wally is a planetologist in the future. He discovers a planet similar to Earth that has two major oceans. Ocean A is very large and looks like it has baseball stitches down its center. Ocean B is very small and has volcanoes all along one side. Wally needs to predict what the planet will look like far into the future. Which prediction would most likely come true? - Ocean A will shrink, and Ocean B will get bigger. - Ocean A will disappear, and Ocean B will remain the same. - Ocean A will get bigger, and Ocean B will shrink. - Both Ocean A and Ocean B will remain the same.

Ocean A will get bigger, and Ocean B will shrink.

Which statement accurately describes one aspect of plate tectonics that involves subduction and seafloor spreading? Older crust is melted at subduction zones. Crust is created at the coastlines of continents. Continents do not move as a result of seafloor spreading and subduction. Crust is created as the mantle hardens under the lithosphere.

Older crust is melted at subduction zones.

Why do rocks on the ocean floor form a pattern of magnetized stripes? - The rocks contain iron that points in the direction the rocks move away from the ridge. - The rocks are composed of different materials depending on when they formed. - The rocks change shapes as a result of the pushing and pulling of seafloor spreading. - The rocks contain iron that points in different directions depending on Earth's polarity.

The rocks contain iron that points in different directions depending on Earth's polarity.

Which information did the Glomar Challenger study in 1968? the rate of seafloor spreading the direction of seafloor spreading the age of rocks in various places in the ocean the contents of rocks in various places in the ocean

the age of rocks in various places in the ocean

What evidence supports Hess's theory of seafloor spreading? Check all that apply. fossils of the same animals found in different areas the direction iron in ocean rocks points the tilt and rotation of the Earth's axis the age of different rocks on Earth's surface pillow-shaped rocks found in the sea

the direction iron in ocean rocks points the age of different rocks on Earth's surface pillow-shaped rocks found in the sea