marine chapter 2
When did the Appalachian Mountains of North America begin to form?
450 million years ago
When did the great mountain ranges of southern Europe and Asia begin to form?
50 million years ago
How are Earth's geographic and magnetic axes oriented relative to each other?
Earth's geographic and magnetic axes are oriented at a slight angle to each other.
Why does the sea floor have a striped pattern of magnetic anomalies that is symmetric with respect to the mid-ocean ridge?
The igneous rock of the ocean floor preserves Earth's existing magnetic field as the rock cools. The polarity of Earth's magnetic field experiences periodic reversals. The ocean floor is spreading apart and new sea floor is forming at the ridge.
Of the following statements about the age of the ocean crust, which one is true? Select only one answer.
The oldest ocean crust is about 200 million years old and is located near an ocean trench.
What was Pangea?
a supercontinent that formed 300 million years ago
Where are most modern divergent plate boundaries found?
at mid-ocean ridges
Where do most earthquakes occur?
at plate boundaries
Where do magnetic field lines exit the Earth today?
at the south pole
Refer again to Figure D1, which is repeated here. In the figure, where would you find the youngest oceanic crust?
c
About 300 million years ago, the Appalachian Mountains in North America were matched up with the identical rocks from which area?
europe
How often does the Earth's magnetic field switch polarity?
every 100,000 to several million years
Which of the following lines of evidence did Alfred Wegener use to support the concept of drifting continents?
everything except the composition of meteors from outer space
What element is responsible for creating the magnetic stripes on the ocean floor?
iron
In terms of heat flow from the Earth's interior, which area would have increased heat flow?
mid-ocean ridges
What piece of evidence supports Wegener's hypothesis of continental drift?
modern-day species that evolved in isolation share a common ancestor
Which type of faulting is associated with the development of new ocean floor?
normal faulting
Most large earthquakes occur along which of the following?
ocean trenches
Where would you expect to see alternating bands of rock with different magnetic polarities?
on both sides of the mid-ocean ridge
Refer to Figure D1. How many periods of reversed polarity are shown in the figure?
one
What did the surface of Earth look like 600 million years ago?
one large continent surrounded by ocean
Which is the largest tectonic plate?
pacific
Which process causes the surface geography of Earth to change over time?
plate tectonics
When was the Precambrian eon?
prior to 600 million years ago
Wegener used which of the following to provide evidence for continental drift?
shape of continental margins
________ is generated by the pull of the weight of a plate as it sinks underneath an overlying plate.
slab pull
The fossil remains of Mesosaurus were found only on which two landmasses?
south america and asia
What is meant by the term plate boundary?
the edge of a plate, where two plates meet each other
Earth's magnetic field is similar to which of the following?
the magnetic field of a bar magnet
Frederick Vine and Drummond Matthews determined that new ocean floor was being produced at ocean ridges by examining:
the magnetic pattern of rocks on the seafloor
What was the one line of evidence that Alfred Wegner could not explain with continental drift?
the mechanism for the movement of the plates
Where would the north end of a magnet point during a time of reverse polarity?
toward the magnetic south pole
When do new oceans form?
when a continent is broken apart by a divergent boundary
Where do most divergent boundaries originate?
within continents
What is the age of the oldest ocean floor?
180 million years
How are normal polarity and reverse polarity of Earth's magnetic field different?
A compass points toward the North Pole during normal polarity and to the South Pole during reverse polarity.
In general, what is our best evidence that the orientation of Earth's magnetic field has changed over time?
A record of Earth's magnetic field is recorded in oceanic rocks, which show a clear pattern of changes in Earth's magnetic polarity.
Which of the following statements about Earth's magnetic field is most accurate?
Earth's magnetic field switches polarity at irregular time intervals.
Why are ocean basins continually being destroyed and created, rather than simply being redistributed around Earth's surface like continents?
High-density oceanic crust subducts beneath low-density continental crust where plates converge.
Of the following statements about ocean crust, which is/are true?
Ocean crust is destroyed at deep sea trenches. Ocean crust is created at the mid-ocean ridge.
Which of the following statements is true regarding tectonic plates?
Tectonic plates may include both oceanic and continental crust.
Of the following statements about sea-floor magnetic anomalies, which is true? Select only one answer.
They are oriented parallel to a mid-ocean ridge.
What did the continents that formed during the break-up of the supercontinent 600 million years ago look like?
They were nothing like the continent shapes we see on Earth today.
As sea floor spreading occurs, what process causes the magnetic stripes on the ocean floor?
a reversal in Earth's magnetic field
On average, how long do periods of reverse and normal polarity last?
about 500,000 years
Who was the first person to advance the idea of mobile continents in 1912?
alfred wegener
What part of the continent(s) create the best fit when trying to piece them back together like a puzzle into the supercontinent Pangaea?
continental margin
What causes melting of material under divergent plate boundaries?
decompression of rock
Magnetic striping occurs at which type of plate boundary?
divergent
Which type of plate boundary is most closely associated with the formation of new ocean floor?
divergent
Based on the Theory of Plate Tectonics, you would expect to find ________ heat flow at the mid-ocean ridge and ________ heat flow at subduction zones when compared to other parts of the crust.
increased decreased
Which of the following tectonic plates are oceanic?
pacific and nazca
What was the name for the supercontinent about 200 million years ago?
pangea
In general, how do magnetic objects align relative to Earth's magnetic field?
parallel
