Exam 1 Chapter 2

What happens when an oceanic and a continental plate converge?

The oceanic plate will be subducted.

Most lithospheric plates contain both oceanic and continental crust.

True

An ocean trench is associated with which type of plate boundary?

convergent

The Hawaiian Islands are associated with which type of plate boundary?

none of the above (The Hawaiian Islands are not associated with any plate boundary.)

How much wider is the Atlantic Ocean today than when Christopher Columbus sailed? Assume that the Atlantic Ocean is getting wider at a rate of 3 centimeters per year (about 1 inch). (Round off the dates to the nearest century to make the calculation simpler.)

15 meters (about 49 feet)

If ocean crust forms at a rate of 10 centimeters per year, how much ocean crust can be created in 20 million years? Select only one answer.

2000 kilometers

Which of the following is the main reason that Earth has a magnetic field? Select only one answer.

Convection in the liquid iron-nickel outer core generates a magnetic field.

Of the following statements about nemataths and volcanic arcs, which is/are true? (All/5)

In a volcanic arc, any of the volcanoes can be active at any time. In a nematath, the age of the volcanoes progressively decreases as you move closer to the volcanic source. A nematath is created by a hotspot. Nemataths and volcanic arcs are both the result of volcanic activity. A volcanic arc is associated with a convergent plate boundary.

What happens when two continental plates converge?

Neither subducts; instead, a mountain range forms.

Of the following statements about ocean crust, which is/are true? (2)

Ocean crust is destroyed at deep sea trenches. Ocean crust is created at the mid-ocean ridge.

Of the following statements about Earth's magnetic field, which is/are true? (All, 5)

The magnetic field is oriented vertical relative to Earth's surface at the south magnetic pole. The magnetic field is oriented horizontal (parallel) to Earth's surface at the magnetic equator. Earth's magnetic field has varying dips around the world that range from vertical to horizontal, depending on latitude. the locations of Earth's magnetic poles have moved through time and have even reversed in polarity. The magnetic field is oriented vertical relative to Earth's surface at the north magnetic pole.

Why does the sea floor have a striped pattern of magnetic anomalies that is symmetric with respect to the mid-ocean ridge? (3)

The ocean floor is spreading apart, and new sea floor is forming. The igneous rock of the ocean floor preserves Earth's existing magnetic field as the rock cools. The polarity of Earth's magnetic field experiences reversals.

How is it that the floor of the ocean is so much younger than the ocean itself?

The ocean floor keeps regenerating itself.

Of the following statements about the age of the ocean crust, which one is true? Select only one answer.

The oldest ocean crust is about 200 million years old and is located near an ocean trench.

What do all plate boundaries have in common? Select only one answer.

They are all associated with zones of earthquakes.

Of the following statements about sea floor magnetic anomalies, which is/are true?

They are oriented parallel to the mid-ocean ridge.

What was the main reason scientists objected to Alfred Wegener's idea of continental drift?

Wegener's proposed mechanism for movement was thought to violate the laws of physics.

Which of the following is associated with a subduction zone?

a volcanic arc

In general, where would the youngest ocean floor be found?

at the mid-ocean ridge

The faster the rate of spreading at the mid-ocean ridge or rise, the ________ the underwater volcanic mountain range.

broader (wider)

Along which of the following would you NOT expect to find active volcanic activity?

continental collision zone

The East Pacific Rise is associated with which type of plate boundary?

divergent

Plate boundaries where new oceanic crust is being added are called _____________.

divergent boundaries

Your job is to locate the world's plate boundaries. To do this, you may use only one map. The best map to choose for this job is a map that shows the worldwide locations of ___________________.

earthquakes

Overall, the Atlantic Ocean basin is ________, and the Pacific Ocean basin is ________.

growing; shrinking

As a tool, paleomagnetism is a piece of modern evidence that has helped support plate tectonics by showing that ________________.

magnetic sea floor "stripes" are symmetric with respect to the mid-ocean ridge

What best describes the tectonic setting of the Cascade Mountains of the Pacific Northwest?

subduction zone

Which of the following lines of evidence did Alfred Wegener use to support the concept of drifting continents? (4)

the way the shapes of the continents fit together like pieces of a jigsaw puzzle the distribution of species of fossils the pattern of similar mountain belts on different continents evidence of glaciers in areas that are now tropical

The San Andreas Fault is associated with which type of plate boundary?

transform

Which of the following tropical islands would likely be the youngest?

tropical island without a fringing reef