Surprisingly, Earth’s magnetic poles have reversed themselves many times during Earth’s history. … Scientists discovered that the rock that makes up the ocean floor lies in a pattern of magnetized “stripes.” These stripes hold a record of reversals in Earth’s magnetic field.
Why are magnetic patterns important?
These patterns of stripes provide the history of seafloor spreading. Geophysicists can read these patterns from the magnetic anomalies they measure with a magnetometer. Where the magnetic wiggles, or anomalies, are broader, the spreading rate has been faster.
What is the significance of magnetic patterns on the seafloor?
When the Earth’s magnetic field reverses, a new stripe, with the new polarity, begins. Such magnetic patterns led to recognition of the occurrence of sea-floor spreading, and they remain some of the strongest evidence for the theory of plate tectonics. The figure below includes two images of the 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.
What is magnetic striping on the seafloor?
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”.
Which magnetic stripe is the oldest How do you know?
The magnetic pole reverses from time to time. 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 do you mean by magnetic reversal?
A change in the Earth’s magnetic field resulting in the magnetic north being aligned with the geographic south, and the magnetic south being aligned with the geographic north. Also called geomagnetic reversal.
Is Earth’s polarity normal or reversed?
This field changes over time, and also behaves differently in different parts of the world. The field can even change polarity completely, with the magnetic north and south poles switching places. This is called a reversal and last happened 780,000 years ago.
What cause the seafloor to spread?
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. Eventually, the crust cracks.
How magnetic symmetry can be used as evidence of seafloor spreading?
Identify how magnetic symmetry can be used as evidence of sea-floor spreading. As the sea floor spreads the magnetic orientation in the rocks as they cooled is preserved. As the earth’s magnetic field changes then a distinct pattern is imprinted in the rocks.
What causes magnetic stripes on the seafloor quizlet?
Stripes of rock formed when Earth’s magnetic field pointed north alternate with stripes of rock that formed when the magnetic field pointed south. The alternating pattern is the same on both sides of a mid-ocean ridge.
What happens when the seafloor spreads?
Sea-floor spreading is what happens at the mid-oceanic ridge where a divergent boundary is causing two plates to move away from one another resulting in spreading of the sea floor. As the plates move apart, new material wells up and cools onto the edge of the plates.
What explains the age and magnetic patterns of seafloor rocks?
When scientists studied the magnetic properties of the seafloor, they discovered normal and reversed magnetic stripes with different widths. These magnetic patterns are parallel to the mid-ocean ridges and symmetrical on both sides. … This is how scientists determine the age of the seafloor.
What does magnetic striping tell us?
Evidence From Magnetic Stripes
You read earlier that Earth behaves like a giant magnet, with a north pole and a south pole. … Scientists discovered that the rock that makes up the ocean floor lies in a pattern of magnetized “stripes.” These stripes hold a record of reversals in Earth’s magnetic field.
What do magnetic anomalies indicate about the earth?
In geophysics, a magnetic anomaly is a local variation in the Earth’s magnetic field resulting from variations in the chemistry or magnetism of the rocks. Mapping of variation over an area is valuable in detecting structures obscured by overlying material.
Where does magnetic striping occur?
At spreading centres, this crust is separated into parallel bands of rock by successive waves of emergent magma. When Earth’s geomagnetic field undergoes a reversal, the change in polarity is recorded in the magma, which contributes to the alternating pattern of magnetic striping on the seafloor.