chapter 17.2 earth science SG
which is younger?
oceanic crust
the study of the history of earths magnetic field
paleomagnetism
harry hess' theory of ________ explained how ocean crust is generated and destroyed
seafloor spreading
the theory that explains how new oceanic crust is formed at ocean ridges, slowly move away from ocean ridges, and destroyed at deep sea trenches is called what?
seafloor spreading
according to the data shown in the figure above, what was Earth's magnetic polarity like 5 million years ago? (hint: compare the colors to see direction)
the reverse of today
T or F: maps made from sonar and magnetometer data showed an ocean floor that had features, such as mountain ranges and trenches, that were bigger than anything found on land
true
an expedition brings up a piece of rock from the Gauss normal epoch. According to the figure, what is the probability that it came from a time when the magnetic field is the same as today
very likely
rock samples taken from areas near ocean ridges were found to be _______ than samples taken from areas near deep-sea trenches.
younger
a _________ ________ happens when the flow in the outer core changes, and Earth's magnetic field changes direction
magnetic reversal
a device that can detect small changes in magnetic fields is called what?
magnetometer
why are magnetic bands in the eastern Pacific Ocean so far apart compared to the magnetic bands along the mid-atlantic ridge?
because the pacific is moving at a faster rate than the atlantic
describe why seafloor spreading is like a moving conveyor belt
in seafloor spreading, new oceanic crust is added at the mid-ocean ridge, and as intrusion continues, seafloor moves towards the edge of the oceanic plate, where it is ultimately pulled back down into the magma below
an imaginary line on a map that shows points that have the same age is called a(n)
isochron
the thickness of ocean sediments that are close to a mid-ocean ridge is ______________ the thickness of ocean sediments that are far from mid-ocean ridges
less than