Investigations of oceanic magnetic anomalies have further corroborated the seafloor spreading hypothesis. Such studies have shown that the strength of the geomagnetic field is alternately anomalously high and low with increasing distance away from the axis of the mid-ocean ridge system.
How do magnetic anomalies support seafloor spreading?
Magnetic surveys over the oceans have revealed a characteristic pattern of anomalies around mid-ocean ridges. … Every few hundred thousand years, the direction of the magnetic field reverses. Thus, the pattern of stripes is a global phenomenon and can be used to calculate the velocity of seafloor spreading.
How do magnetic anomaly patterns on the ocean floor best serve as evidence for seafloor spreading?
Seafloor spreading was confirmed by discovery of magnetic anomalies in the ocean crust that were both parallel to and symmetric around the ocean ridges. … As the plates move over the asthenosphere, they separate mostly at oceanic ridges and collide and are subducted into Earth’s interior at oceanic trenches.
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 is seafloor spreading?
Seafloor spreading is a geologic process in which tectonic plates—large slabs of Earth’s lithosphere—split apart from each other.
What is the character of magnetic anomalies on the seafloor?
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…
What is the first step of seafloor spreading?
A crack forms in oceanic crust. Molten rock rises up through oceanic crust. Molten rock solidifies at the center of the ridge.
What is the major evidence that seafloor spreading creates new lithosphere?
When the Earth’s magnetic field reverses, the magnetized minerals align in the opposite direction. The record of magnetic reversals is carried away from each side of the spreading center of a mid-ocean ridge, showing that the molten rock is creating new lithosphere.
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 used as evidence for seafloor spreading?
Several types of evidence supported Hess’s theory of sea-floor spreading: eruptions of molten material, magnetic stripes in the rock of the ocean floor, and the ages of the rocks themselves. This evidence led scientists to look again at Wegener’s hypothesis of continental drift.
What kind of rock is the seafloor made of?
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 are the three types of seafloor spreading?
There are three types of plate-plate interactions based upon relative motion: convergent, where plates collide, divergent, where plates separate, and transform motion, where plates simply slide past each other.
Why is seafloor spreading important?
Significance. Seafloor spreading helps explain continental drift in the theory of plate tectonics. … At a spreading center, basaltic magma rises up the fractures and cools on the ocean floor to form new seabed. Hydrothermal vents are common at spreading centers.
Where is active seafloor spreading occurring today?
Where is active sea floor spreading occurring today? Seafloor spreading is the movement of old rock that is being pushed by the new young oceanic crust. This would be a divergent since the plates are separating from each other. Active seafloor spreading is occurring at mid-ocean ridges.