Module 6 - The Active Earth: Plate Tectonics
Continental drift
Alfred Wegener's ____ theory hypothesized that Earth's continents were once joined together and later split, and drifted apart.
Changes in the Moon's orbit due to shifting plates
All of the following are evidence supporting the theory of plate tectonics except for ________.
Subduction zones along convergent plate boundaries
Cooler, older, oceanic lithosphere sinks into the mantle at ________.
Hot spot
A very long-lived stationary magma plume located deep in the mantle is called a ________.
Metallic elements
In order to measure the orientation of Earth's magnetic field a rock would need to contain ______.
Centimeters
Tectonic plates typically move at rates of 1 to about 16 ____ per year.
Convergent
The Himalayan Mountain Range is an example of a ____ boundary.
Lithosphere
The _______ includes Earth's crust and the uppermost strong and ridgid part of the mantel.
Ridge push
The downslope sliding of the lithosphere away from a spreading center is called a ____.
Convection
The entire mantle-lithosphere system circulates in large ____ cells.
Rift valley / divergent
The feature created in this diagram is called a ________ and is produced at ________ plate boundaries.
Older
The seafloor and oceanic crust at the Mid-Atlantic Ridge becomes ____ with increasing distance from the ridge axis.
Isostatic adjustment
The weight of an ice sheet can cause the continental lithosphere to sink into the underlying asthenosphere due to ____.
The Mid-Oceanic Ridge is elevated above surrounding seafloor because it is made of hotter and less dense lithosphere than oceanic crust farther away from the divergent boundary.
True or False:
True
True or False: A single plate can carry both oceanic and continental crust.
True
True or False: Continental crust does not normally sink into the mantle because continental crust is of lower density than mantle material.
False
True or False: Continental rifting occurs when two continental plates converge.
True
True or False: The Himalayan Mountains are the tectonic product of a collision between India and Eurasia that began in Eocene time and still continues.
False
True or False: The inner core is molten.
False
True or False: The interior of lithospheric plates are normally tectonically active with occurrences of earthquakes and volcanoes.
True
True or False: The lithosphere floats on the asthenosphere.
True
True or False: The oldest rocks of the oceanic crust are found in deep ocean trenches far away from active, mid-ocean ridges.
False
True or False: The reaction among the scientific community to Wegener's supercontinental theory was very positive.
False
True or False: Young oceanic crust is more dense than older oceanic crust.
The oceanic plate sinks beneath the continental plate and dives into the mantle
When a plate carrying continental crust converges with a plate carrying oceanic crust ____.
Huge mountain ranges
When two continental plates converge, they form ____.
huge mountain ranges
When two continental plates converge, they form ____.
The older, denser plate sinks into the mantle
Where two plates carrying oceanic crust converge ____.
A. continents
Which of the following contains the oldest rocks? A. continents B. seafloors C. spreading centers D. ocean ridges
Fossil records
Which of the following provided evidence for Wegener's theory?
Mid-ocean ridges and rift valleys
Which two features are commonly found at divergent plate boundaries?
Magnetic reversals
____ have occurred on average every 500,000 years during the past 65 million years of Earth's history.