Question

the diagram above shows the magnetism of the earths crust on both sides of a mid - ocean ridge.
question

1. what do you observe about the pattern of magnetism in the crustal rocks on either side of the mid - ocean ridge?
2. please explain the processes occurring at the mid - ocean ridge that have created the pattern of magnetism you observe.

Explanation:

Sub - question 1

By visually inspecting the diagram, we can see that the magnetic pattern (including the sequence of normal and reversed magnetism and the magnetic anomaly curves) of the crustal rocks on one side of the mid - ocean ridge is a mirror image of the pattern on the other side. For example, the order of magnetic periods like Gilbert (reversed), Gauss (normal), Matuyama (reversed), etc., is symmetric with respect to the mid - ocean ridge. Also, the magnetic anomaly curves (the wavy lines at the top) on either side of the ridge have a symmetric pattern.

1. Seafloor Spreading at Mid - Ocean Ridge: At the mid - ocean ridge, the asthenosphere (molten rock) rises up. As it reaches the surface (the ridge), it cools and solidifies to form new oceanic lithosphere (crust).
2. Magnetic Alignment: When the molten rock (magma) cools, the magnetic minerals within the rock align themselves with the Earth's magnetic field at that time. The Earth's magnetic field has reversed its polarity multiple times in the past (normal to reversed and vice - versa).
3. Symmetric Formation: As new crust is formed at the ridge and the existing oceanic lithosphere moves away from the ridge (the arrows in the diagram show the direction of movement), the newly formed crust on one side of the ridge and the crust that has moved away on the other side record the same magnetic history. So, when the magnetic field reverses, the new crust formed after the reversal will have the new magnetic polarity. Since the spreading is symmetric (the crust moves away from the ridge in both directions), the magnetic pattern on both sides of the ridge ends up being a mirror image of each other.

Answer:

The pattern of magnetism in the crustal rocks on either side of the mid - ocean ridge is symmetrical (mirror - image) in terms of the sequence of normal and reversed magnetism and the magnetic anomaly patterns.

Sub - question 2