Most Oceanic Plateaus Are

constructed by volcanic eruptions probably over mantle plumes.

Most oceanic plateaus are

Picture

This figure shows parts of South America, Africa, and the intervening Atlantic Ocean. Drag the label for each tectonic feature to its correct position on the figure.

subduction.

The process of one plate sliding beneath another plate is called

Subduction brings one plate to a depth hot enough for minerals to release water; this water causes melting in the overlying asthenosphere.

How is magma created in a subduction zone?

solid mantle in the asthenosphere rises toward the surface and begins to melt due to decompression.

At mid-ocean ridges, as two plates diverge,

Photo (Video)

How did the Red Sea, shown between Arabia and Africa in this figure, form?

mid-ocean ridge.

A divergent plate boundary is most likely associated with a(n)

island arc

Which of the following features is associated with a deep oceanic trench?

iron-rich minerals align with Earth's magnetic field.

Magnetic patterns develop on the seafloor as basaltic lava erupts and cools, and

A (Picture)

Which area(s) on this world map is (are) likely to have volcanoes above sea level?

seafloor spreading.

Harry Hess and Robert Dietz proposed that the oceanic crust in the Atlantic Ocean was spreading apart at the Mid-Atlantic Ridge and that this process moved the continents apart from one another. They called this process

Seafloor is added to both sides during seafloor spreading. (picture)

On this map of the south Atlantic, why is the mid-ocean ridge in the center of the ocean?

6 (Picture)

This diagram shows magnetic stripes on either side of the mid-ocean ridge. The number of different ages of stripes represented in this diagram is ____.

subduction of oceanic crust (photo)

In this figure of Japan, what do the offshore trenches indicate?

boundaries.

Intense geologic activity occurs at plate

All of these choices are correct.

A force that is important in driving plate tectonics is

oceanic fracture zones.

Cracks and steps that cross the seafloor and run at right angles to mid-ocean ridges are called

1 (photo)

This figure shows ages of seafloor. The oldest ocean floor is at site numbered ___.

both types of crust and the uppermost mantle

The lithosphere consists of ____________________________.

continental shelves.

Some continents continue outward from the shoreline under shallow seawater, forming submerged benches called

(Picture)

This figure shows the four stages of continental rifting. First, drag each of the four descriptions to its appropriate position on the figure, and then drag each of the three place names to the figure that best represents the modern-day setting of that place.

away from each other (Photo)

Which way are the plates moving in this figure?

Some asthenosphere becomes lithosphere at mid-ocean spreading centers and reenters the asthenosphere at subduction zones.

Select the statement that best describes how the process of plate tectonics circulates materials between the asthenosphere and the lithosphere.

the plate moves relative to the underlying hot spot.

Hot spots form linear island chains because

oceanic divergent boundary (photo)

What type of plate boundary is depicted in this figure?

oceanic trench.

A convergent plate boundary is most likely associated with a(n)

continental shelves

Which of the following parts of the seafloor are the shallowest?

(Picture)

On this map of the world, drag the label for each tectonic plate to its correct position on the figure.

continental rift (Photo)

What type of plate boundary is depicted in this figure?

continental collision (photo)

Why does the Tibetan Plateau, shown in this figure, have a high elevation?

B and C (photo)

The plate boundary on the this figure is located between:

mid-ocean ridge.

An oceanic transform plate boundary is most likely associated with a(n)

Oceanic crust is created.

What occurs at mid-ocean ridges?

B (picture)

On the accompanying figure, which letter is likely over oceanic crust that is similar in age to that beneath letter E?

continental collision. (picture if you need)

The convergence of two continental masses is known as a(n)

divergent and transform (picture)

What types of plate boundaries are shown in this figure?

northwest (picture)

This figure shows a northwest-southeast line of islands and seamounts near Hawaii. If location 3 has the oldest rocks and Hawaii (1) has the youngest rocks, which way is the plate moving with respect to the hot spot?

A compass needle would point south.

What is associated with reversed magnetic polarity?

continental shelves and slopes along passive margins

In what setting does the thickest sediment accumulate in the oceans?

oceanic trenches.

The deepest parts of the seafloor are

different in character and origin from curved island arcs.

Island chains and seamounts cross parts of the ocean floor. These oceanic islands and associated seamounts are

movement of iron and electrical currents within Earth's outer core.

The Earth's magnetic field is generated by

(Picture)

On this map of the world, drag the label for each type of feature to an appropriate position on the figure.

centimeters per year

How fast do plates move relative to one another?

Sometimes Earth's magnetic field points north and sometimes it points south. (Picture)

What causes magnetic stripes on the seafloor, such as those shown here?

mid-ocean ridges

What setting has the thinnest cover of sediment in the oceans?

A (photo)

On the accompanying figure, which letter is over the oldest oceanic crust?

60 kilometers per million years. (photo)

If the area shown in this figure is 240 kilometers wide, and the oldest crust is 4 million years old, the approximate spreading rate is __________.

(photo)

On this map of the world, drag the label for each place to its correct position on the figure.

Spreading along the Atlantic ridge added seafloor to plates on both sides, while subduction has consumed large areas of old oceanic crust in the Pacific.

On a map showing the age of the seafloor, why are the patterns symmetrical in the Atlantic Ocean but not the Pacific Ocean?

All of these typically mark continental hot spots. (continental rifting, abundant volcanism, high elevations.)

Continental hot spots are typically marked by

there was no mechanism to move continents through the oceanic crust.

The main reason why the hypothesis of continental drift was not widely accepted was

constructed by volcanic eruptions that first occur under water.

Most oceanic islands and seamounts are

melting along a mid-ocean ridge

A continent has an oceanic trench offshore of its coast. Which of the following is probably NOT present along this side of the continent?

(photo)

Drag each feature name into the lower box near its proper place. Into the place above the feature name, drag the description that best describes how this feature forms.

ocean-continent convergent boundary (picture)

This figure depicts what type of boundary?

30 km/m.y.

If a magnetic stripe is 120 km wide and formed over 4 m.y., what would the rate of seafloor spreading be?

All of these choices are correct. (the distribution of glacial deposits and directions of glacial scratch marks, the distribution of fossils, the shape of the continents)

Which data were used to develop the hypothesis of continental drift?

the crust is thicker

A region generally is higher than an adjacent region if __________________________ than in the adjacent region.