Exam 2: Plate Tectonics: a Unifying Theory

Radiometric dating shows that the oldest ocean crust is ____________________ years old and the oldest continental crust is ____________________ years old.

Explain how mountain ranges can be used as evidence to support continental drift.

List two ways that glacial deposits give strong evidence of the existence of Gondwana.

The Appalachian Mountains of the eastern United States are thought to have once been joined with mountains located in which other continental regions?

In what ways does plate tectonics theory have economic applications?

Volcanoes are found at these two types of plate boundaries: ____________________ and ____________________.

Where in the ocean basins is ocean crust youngest?

Completion Wegener proposed that the continents were once all together as a supercontinent he named ____________________, which then split into a northern supercontinent called ____________________ and a southern supercontinent called ____________________.

What is the driving mechanism for plate tectonics?

At a convergent plate boundary, oceanic crust is ____________________.

Around most of the Atlantic the continental slope descends into an oceanic trench but around the Pacific the continental slope merges with a more gently sloping continental rise.

How does the introduction of a geographic barrier encourage the evolution of species?

What evidence is there that ocean basins are young and old oceanic crust must be destroyed?

Aseismic ridges have that name because they do not indicate occurrences of earthquakes.

Where divergent plate boundaries form beneath continental masses, low areas known as ____________________ form.

What do glacial striations indicate?

Draw a cross-section of an oceanic-continental convergent plate boundary. Show the directions of relative plate motion. Put stars for the locations of earthquakes. Put triangles with smoke out the top for the locations of volcanoes. Label the trench and subduction complex.

At deep-sea trenches, ____________________ is subducted back into the ____________________.

Paleomagnetism is the study of the ____________________ magnetism in rocks. When magma cools, the magnetic iron-bearing minerals align themselves with the Earth's magnetic field and record ____________________ and ____________________.

At a mid-oceanic ridge spreading center: