ch 2

supercontinent 250 million years ago

Pangaea

Do most lithospheric plates contain both oceanic- and continental-type crust?

Yes, most lithospheric plates contain both oceanic- and continental-type crust.

Convergent plate boundaries occur when tectonic plates move in opposite directions.

False

Water depth decreases as you move away from the mid-ocean ridge.

False

The book The History of Ocean Basins, which contained the idea of seafloor spreading, was written by geologist:

Harry Hess.

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

Ocean crust is destroyed at deep sea trenches.

Tectonic plates are pieces of the ________ that float on the more fluid ________ below.

lithosphere; asthenosphere

A researcher interested in the vertical zonation of oceanic lithosphere would want to study __________.

ophiolites

The study of historical changes of continental shapes and positions is called:

paleogeography.

study of magnetism over geologic time

paleomagnetism

New crust is formed at trenches and older crust is subducted at oceanic ridges.

false

The magnetic field of the Earth reverses itself each time that magma erupts at a mid-ocean ridge.

false

The magnetic north pole has remained very close to the geographic North Pole throughout all of geologic time.

false

The majority of the world's hotspots are associated with plate boundaries.

false

Climate distribution on Earth is primarily controlled by:

latitude

Earthquakes can occur only in the __________.

lithosphere

volcanoes on the seafloor that are flat-topped because of wave erosion are called:

tablemounts.

Which of the following is characteristic of continental-continental convergent plate boundaries?

uplifted mountain ranges

How can plate tectonics be used to help explain the difference between a seamount and a tablemount?

A seamount is a volcano with a cone-shaped top, whereas a tablemount is a volcano with a flattened top. Though both of these features originate at the crest (and topographic high) of the mid-ocean ridge, a tablemount has been subject to wave erosion when it rises above sea level. When the crust containing the tablemount is pushed away from the crest (and therefore onto a topographically lower position), or is moved away from a hot spot, it is re-submerged with its flat top.

The cities of Los Angeles and San Francisco, CA, are about 380 miles apart. Plate motion along the San Andreas Fault is about five centimeters per year. If the Los Angeles Dodgers and the San Francisco Giants continue to play at their current locations, how long will it be before their games will constitute a cross-town rivalry?

About 12,230,000 years

Describe seafloor spreading and why it was an important piece of evidence in support of plate tectonics.

Captain Hess suggested that new ocean crust was created at the mid-oceanic ridges and disappeared back into deep Earth at the trenches near the edges of ocean basins. This was an important piece of evidence in support of plate tectonics because it provided a mechanism for continental and oceanic plate motion.

The first scientist to propose the origin of coral reefs based upon subsidence (sinking) of volcanic islands was:

Charles Darwin.

Regarding glacial ages, why is it unlikely that the entire world was covered by ice 300 million years ago?

Coal deposits from the same geologic age are now present in North America and Europe, which formed from the remains of vast tropical swamp plants.

Iceland is located on what type of plate boundary?

Divergent

Describe Earth's magnetic field, including how it has changed through time.

Earth's magnetic field is composed of invisible lines of magnetic force that originate within Earth and travel out into space. The polarity of the field has reversed itself throughout geologic time.

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

In a volcanic arc, any of the volcanoes can be active at any time.

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

The magnetic field is oriented vertical relative to Earth's surface at the south magnetic pole.

How is the age distribution pattern of the Hawaiian Islands-Emperor Seamount chain explained by the position of the Hawaiian hot spot?

The volcanoes in the Hawaiian Island-Emperor Seamount chain get progressively older as one heads northwestward from Hawaii. These age relationships suggest that the Pacific Plate has been steadily moving northwestward, while the underlying mantle plume has remained relatively stationary.

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

They are all associated with zones of earthquakes.

Charles Darwin was the first person to propose a hypothesis on the origin of coral reefs.

True

Deep-sea trenches are found at convergent plate boundaries.

True

Evidence for continental drift includes:

all of the above.

Which of the following is characteristic of oceanic-continental convergent plate boundaries?

andesitic volcanoes

The Mid-Atlantic Ridge is an example of a:

divergent plate boundary.

The Hawaiian Islands are located where the Pacific plate is:

moving over a hot spot or mantle plume.

The seafloor magnetic pattern is best described as:

parallel to and symmetric about mid-ocean ridges.

Fossils of ancient polar plants are currently found near the equator because the:

plants lived near the poles, but landmasses have drifted to current locations.

seafloor magnetic stripes

spreading center

island arc

subduction zone

trench

subduction zone

Loihi is __________.

the newest Hawaiian volcano

Areas of intense volcanic activity that remain in more or less the same location over long periods of geologic time and are unrelated to plate boundaries are called hotspots.

true

The Wilson Cycle uses plate tectonic processes to show the life cycles of ocean basins during their growth, formation, and destruction over geologic time.

true