Geology 1010 Lecture 2 Exam with
Complete Solutions
Why was the continental drift hypothesis dismissed so quickly? - Answer- Wagner did
not have an explanation for HOW the plates moved
Why was new research of the ocean floor conducted in the 1940s-1960s? - Answer-
submarine warfare in WW2
What is the Mid Ocean Ridge (MOR)? - Answer- huge underwater mountain range all
the way around the planet
Why are there magnetic anomalies in seafloor rocks? - Answer- iron and other materials
pointing north and south
What did the discovery of reverse polarity mean? - Answer- that earth's magnetic field
reverses itself over time
What is magnetic reversal? - Answer- when the magnetic field flips itself backwards and
magnets point south instead of north; the planet itself does not flip; occurs every few
million years
What is seafloor spreading? - Answer- MOR is really a series of volcanoes constantly
erupting and forming new rock; the young rock then pushes the old rock out of the way
forming a mirror image on the ocean floor
What are the 4 ways plates move? - Answer- convection, ridge push model, slab pull
model, slab suction
describe convection - Answer- the asthenosphere contain convection cells that do
something similar to a boiling pot of water, moving materials up and down as density
rises and falls. Lithospheric plates sit on top and are moved by this
Describe ridge push model - Answer- magma pushes up between plates and slides
plates to the left or right
Describe slab pull model - Answer- occurs at trenches in the bottom of the ocean away
from MOR; gravity pulls one plate under the other
Describe slab suction - Answer- slab pull tugs plate downward and asthenosphere is
pulled down too; lots of friction and pressure
Complete Solutions
Why was the continental drift hypothesis dismissed so quickly? - Answer- Wagner did
not have an explanation for HOW the plates moved
Why was new research of the ocean floor conducted in the 1940s-1960s? - Answer-
submarine warfare in WW2
What is the Mid Ocean Ridge (MOR)? - Answer- huge underwater mountain range all
the way around the planet
Why are there magnetic anomalies in seafloor rocks? - Answer- iron and other materials
pointing north and south
What did the discovery of reverse polarity mean? - Answer- that earth's magnetic field
reverses itself over time
What is magnetic reversal? - Answer- when the magnetic field flips itself backwards and
magnets point south instead of north; the planet itself does not flip; occurs every few
million years
What is seafloor spreading? - Answer- MOR is really a series of volcanoes constantly
erupting and forming new rock; the young rock then pushes the old rock out of the way
forming a mirror image on the ocean floor
What are the 4 ways plates move? - Answer- convection, ridge push model, slab pull
model, slab suction
describe convection - Answer- the asthenosphere contain convection cells that do
something similar to a boiling pot of water, moving materials up and down as density
rises and falls. Lithospheric plates sit on top and are moved by this
Describe ridge push model - Answer- magma pushes up between plates and slides
plates to the left or right
Describe slab pull model - Answer- occurs at trenches in the bottom of the ocean away
from MOR; gravity pulls one plate under the other
Describe slab suction - Answer- slab pull tugs plate downward and asthenosphere is
pulled down too; lots of friction and pressure
