chapter 17 earth science
What is the study of the Earth's ancient magnetic record?
paleomagnetism
The supercontinent from Wegener's theory of continental drift is called ___________________________.
pangaea
The tremendous amount of heat within the Earth powers ___________________
plate tectonics
What causes the seafloor to spread?
rising molten magma
Harry Hess's theory of _________________________ explained how ocean crust is generated and destroyed.
seafloor spreading
LOOK AT THE FIGURE AND identify the subduction zone
D
Where are the youngest rocks on the ocean floor located?
at the mid-ocean ridges
The subduction of an oceanic plate beneath a continental plate produces a(n) ____________________________
chain of volcanic mountains
What is the name of Alfred Wegener's hypothesis about moving land masses?
continental drift
Places where two tectonic plates are moving away from each other are called _____________________________.
divergent boundaries
What evidence did Wegener use to estimate the time of the continent Pangaea's break up into smaller continents?
fossil data
What is an isochron ?
a line on a seafloor map that connects points of equal age
During the time of Pangaea, what had the greatest impact on Earth's climate?
it was a time of a giant global ocean
Which mineral may preserve magnetic patterns on the ocean floor, in support of tectonic plates?
magnetite
A ___________________ is a device that can detect changes in the strength of the Earth's magnetic field.
magnetometer
What two topographic features of the ocean floor were discovered only with the use of sonar?
mid-ocean ridges and deep-sea trenches
When a divergent plate boundary forms on a continent, (land), a ___________________forms.
rift valley
Much of the Earth's internal heat comes from ________________________
the decay of radioactive materials
A place where two plates slide laterally past each other is called a _______________________________
transform boundary
Rocks close to the mid-ocean ridge are _____________________ rocks far from the mid-ocean ridge.
younger than