Exam 2: Plate Tectonics: a Scientific Revolution Unfolds

In which decade was the theory of plate tectonics developed?

Subduction zones will only develop between a continental plate and an oceanic plate.

________ occurs when magnetic minerals in lavas align their magnetic fields with magnetic north, preserving a record of that pole's location at that moment in time.

If there is no compositional difference between two oceanic plates, what other factor will determine which plate will become the subducted one and why? (What other factor can control density?)

Which is least dense?

When considering evidence of glaciation on the southern continents, why did Wegener reject the explanation that the entire planet had experienced a period of extreme cooling?

Which model of convection describes how the interior is divided into several levels of convection cells?

The ________ is a hotter, weaker region in the mantle that lies below the lithosphere and responds to forces by flowing.

There is an expression in American society that it would only take one good earthquake and the state of California would sink into the ocean.Using what you know about plate boundaries, evaluate this statement.

What two pieces of information would researchers need to have in order to calculate the rate of plate motion for seafloor spreading?

An oceanic plate that has been permeated by water before subduction will trigger melting sooner than a "dry" oceanic plate.

At a ________, an oceanic plate will be forced beneath another plate because of differences in density.

What is a mantle plume?

Alfred Wegener provided several pieces of evidence supporting the idea that the planet's continents were once joined in a single landmass.List three of them.

The majority of divergent plate boundaries are associated with oceanic ridges.

Which is denser: a 100-million-year-old oceanic lithosphere near a convergent boundary, a 15-million-year-old oceanic lithosphere near a rift, or the upper part of the asthenosphere?

What is slab pull?

Lava solidifying during a period of reverse polarity will align the magnetic fields of its iron particles toward the ________ pole.

In the mid-twentieth century, researchers dredging the seafloor could not find any materials older than ________.

Mesosaurus is a small freshwater reptile that existed in the Permian Period.It is only found in black shale deposits in eastern South America and southwestern Africa.If the Mesosaurus is an aquatic reptile and the continents are currently separated by an ocean, evaluate why the Mesosaurus would be used as strong evidence in favor of continental drift rather than as evidence against it.