Question

The symmetric pattern of seafloor magnetic intensity and polarity centered on mid-ocean ridges suggests that

1. new oceanic crust is being generated at mid-ocean ridges
2. old oceanic crust is being destroyed at mid-ocean ridges
3. the direction of the Earth's magnetic field lines has remained the same throughout Earth history
4. the composition of oceanic crust must fluctuate with increasing distance from mid-ocean ridges
5. the intensity and polarity of Earth's magnetic field fluctuates across mid-ocean ridges

Answer 1

The symmetric pattern of seafloor magnetic intensity and polarity centered on mid-ocean ridges suggests the generation of new oceanic crust through seafloor spreading.

Step-by-step explanation:

The symmetric pattern of seafloor magnetic intensity and polarity centered on mid-ocean ridges suggests that new oceanic crust is being generated at mid-ocean ridges. This pattern is known as marine magnetic anomalies and is formed due to the process of seafloor spreading.

As the tectonic plates diverge at mid-ocean ridges, magma rises from the mantle and solidifies to form new oceanic crust. This newly formed crust inherits the polarity of Earth's magnetic field at the time of its formation. Over time, as Earth's magnetic field flips its polarity, the new crust also adopts the opposite polarity. These magnetic reversals can be observed in the rock record and are consistent with our understanding of plate tectonics and the movement of Earth's magnetic field.