When lava gets erupted at the mid-ocean ridge
axis it cools and turns into hard rock
. … This creates a symmetrical pattern of magnetic stripes of opposite polarity on either side of mid-ocean ridges. These patterns of stripes provide the history of seafloor spreading.
What does the pattern of magnetic stripes on the seafloor indicate quizlet?
Why does the rock of the ocean floor have a pattern of magnetic stripes? The rock of the ocean floor contains iron.
As molten material cooled and hardenend, the iron bits inside lined up in the direction of Earth’s magnetic poles
, creating a pattern of magnetized stripes.
How does the pattern of magnetic stripes give evidence for seafloor spreading?
How do strips of magnetized rock on the ocean floor provide evidence of sea-floor spreading? Strips of ocean-floor basalt
record the polarity of Earth’s magnetic field at the time the rock formed
. … The pattern shows that ocean floor forms along mid-ocean ridges and then moves away from the ridge.
What is magnetic striping on the seafloor?
What Is Magnetic Striping? Magnetic Striping is
when the sea floor is spreading, and magma from the mantle is rising through the Earth’s crust
. That magma then turns into new crust, forming the “Oceanic Crust”.
How do magnetic stripes form on the ocean floor?
The striped magnetic pattern develops because,
as oceanic crust pulls apart, magma rises to the surface at mid-ocean ridges and spills out
to create new bands of ocean floor.
What causes the strange stripes on the seafloor?
When scientists plotted the points of normal and reversed polarity on a seafloor map they made an astonishing discovery: the
normal and reversed magnetic polarity of seafloor
basalts creates a pattern. Stripes of normal polarity and reversed polarity alternate across the ocean bottom.
Which magnetic stripe is the oldest How do you know?
The north pole becomes the south pole, and the south pole becomes the north pole. Rocks of normal and reversed polarity are found in stripes symmetrically about the mid-ocean ridge axis. The seafloor is youngest at the
ridge
crest and oldest far away from the ridge crest.
What does the presence of new rock near an ocean ridge indicate?
There is always a deep-sea trench underneath.
There is evidence of seafloor spreading
. They are made from oceanic crust.
What are 2 pieces of evidence that support seafloor spreading?
Look at Figure 19 to see the process of sea-floor spreading. Several types of evidence from the oceans supported Hess’s theory of sea-floor spreading-
evidence from molten material, magnetic stripes, and drilling samples
. This evidence also led sci- entists to look again at Wegener’s theory of continental drift.
Where does seafloor spreading occur?
Seafloor spreading occurs
at divergent plate boundaries
. As tectonic plates slowly move away from each other, heat from the mantle’s convection currents makes the crust more plastic and less dense. The less-dense material rises, often forming a mountain or elevated area of the seafloor.
What does magnetic striping prove?
During times of normal magnetic polarity, the rocks being created stayed normal. … If they were created during times of reverse polarity, the rocks would freeze that magnetic orientation in place.
What is magnetic striping evidence of?
Magnetic striping is evidence of
seafloor spreading
.
What do magnetic anomalies indicate about the earth?
A magnetic anomaly is
the change in magnitude of the earth’s magnetic field with respect to the expected value for that location
. Large volumes of magnetic materials will change the intensity of the earth’s field.
What kind of magnetism do rocks right at mid-ocean ridges have?
When lava is extruded at any mid-ocean ridge, the rock it forms becomes
magnetized
and acquires the magnetic polarity that exists at the time the lava cools. As the crust moves away from mid-ocean ridges, it contains a continuous record of the Earth’s changing magnetic polarity.
What is the pattern seen in the ages of the seafloor?
What do you notice about the age pattern on the seafloor in the Atlantic Ocean (hint: look on each side of the middle)? The age pattern
is symmetric
. Youngest ages are at the middle of the pattern (on the oceanic ridges) and the seafloor grows older moving outwards to each side of the middle.
What are magnetic anomalies on the ocean floor?
A marine magnetic anomaly is
a variation in strength of Earth’s magnetic field caused by magnetism in rocks of the ocean floor
. Marine magnetic anomalies typically represent 1 percent of the total geomagnetic field strength. They can be stronger (“positive”) or weaker (“negative”) than the average total…
