Geology Ch 2

What is the typical rate of seafloor spreading in the Atlantic Ocean?

2 centimeters per year

What is the temperature that magnetite loses its magnetization?

800 degrees C

What causes the volcanoes and deep valleys of East Africa?

A continental rift along parts of the African continent beginning to slowly separate

What type of boundary occurs along the Aleutian Islands in the North Pacific?

A convergent boundary on a volcanic arc above the northward-subducting Pacific plate

A transform plate boundary is characterized by __________.

A deep, vertical fault along which two plates slide past one another in opposite directions

What type of plate boundary is usually associated with pull-apart rift zones?

A divergent plate boundry

What type of region is the modern-day Red Sea?

A rift zone that may eventually open into a major ocean if Arabia and Africa continue to seperate

Which of the following statements applies to the asthenosphere, but not the lithosphere?

A zone in the upper mantle that deforms by plastic flowage

Which scientist argued forcefully for continental drift in the early part of the 20th century?

Alfred Wegner

Where in the ocean does oceanic lithosphere sink into the mantle?

At subduction zones along convergent plate boundaries

Why was Wegener's continental drift hypothesis rejected?

Because Wegener could not identify a mechanism capable of moving continents

Which one of the following is an important fundamental assumption underlying the plate tectonic theory?

Earth's diameter has been essentially constant over time.

What was the name of the fossil flora that grew on Pangaea during the late Paleozoic?

Glossopteris

A very long-lived magma source located deep in the mantle is called a(n) __________.

Hot spot

Which of the following was never proposed as evidence supporting the existence of Pangaea?

Islands along the Mid-Atlantic Ridge with rocks dating back from 542 million to 2500 million years ago

What causes the linear patterns associated with paleomagnetism on either side of mid-oceanic ridges?

Normal and reversed magnetized strips roughly parallel to the ridge

The former, late Paleozoic supercontinent is known as __________.

Pangea

Which of the following is not evidence supporting the theory of plate tectonics?

Shifting plates were caused by changes in the Moon's orbit.

What process is evident at oceanic trenches?

Sinking of oceanic lithosphere into the mantle at a subduction zone

Which of the following is an example of an active continent-continent collision?

The northward movement of India into Eurasia see

What evidence did the Deep Sea Drilling Project find about the dates of rocks in the ocean basins?

The ocean basins are relatively young; most ocean basin rocks and sediments are Cretaceous or younger in age.

Which of the following properly describes Mount St. Helens and the other Cascade volcanoes?

They are young, active volcanoes built on a continental margin above a sinking slab of oceanic lithosphere.

Which of the following paleoclimatic evidence supports the idea of the late Paleozoic supercontinent in the Southern Hemisphere?

Tillites (rocks formed by glaciers) in South Africa and South America

Which two scientists proved that a symmetrical magnetic pattern existed in seafloor basalts and related those stripes to spreading at a mid-oceanic ridge?

Vine and Matthews