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:

Question 1

Step1: Analyze the Magnetic Anomaly Pattern

Looking at the diagram, the magnetic anomalies (the colored bands and the magnetic reading graph) on either side of the mid - ocean ridge (the ridge marked in the diagram) are symmetric. The sequence of normal and reversed magnetism (shown by the labels like Gilbert reversed, Gauss normal, etc. and the magnetic anomaly graph) is mirrored across the mid - ocean ridge. For example, the pattern of magnetic bands (green and other colored regions) and the magnetic intensity fluctuations (in the top graph) on the left side of the ridge is the same as on the right side.

Step2: Confirm the Symmetry

By visually inspecting the diagram, the magnetic pattern (both the magnetic anomaly graph and the magnetic polarity bands) on the ocean lithosphere on the left of the ridge is a mirror image of the pattern on the right of the ridge. The direction of the arrows (showing plate movement) also supports that the rocks are moving away from the ridge, and the magnetic pattern is symmetric with respect to the ridge axis.

Step1: Identify the Process at Mid - Ocean Ridge

The mid - ocean ridge is a divergent plate boundary. At the mid - ocean ridge, magma rises from the asthenosphere (the red region in the diagram) to the surface. This magma, when it cools and solidifies to form new oceanic lithosphere, records the Earth's magnetic field at the time of its formation.

Step2: Explain Magnetic Striping Formation

As the new oceanic crust is formed at the ridge, the tectonic plates (ocean lithosphere) move away from the ridge (as indicated by the black arrows in the diagram, moving in opposite directions). Over time, the Earth's magnetic field undergoes reversals (normal to reversed and vice - versa). Each time new magma erupts at the ridge, cools, and solidifies, it acquires the current magnetic polarity of the Earth. Since the plates move away from the ridge, the newly formed crust with its magnetic signature is carried away from the ridge. As a result, the magnetic pattern (sequence of normal and reversed magnetism) is symmetric because the rocks on both sides of the ridge are formed at the ridge and then move away, with each new batch of magma recording the magnetic field at the time, leading to a striped (banded) pattern of normal and reversed magnetism that is symmetric across the ridge.

Step3: Connect to Symmetry

The symmetry occurs because the rate of plate movement away from the ridge is relatively constant on both sides, and each new segment of crust formed at the ridge has a magnetic polarity corresponding to the Earth's field at that time. So, the pattern of magnetic polarities (normal and reversed) is repeated on both sides of the ridge as the plates spread apart, creating the symmetric magnetic pattern observed.

Answer:

The pattern of magnetism in the crustal rocks on either side of the mid - ocean ridge is symmetric. The sequence of normal and reversed magnetic polarities (and the corresponding magnetic anomalies in the graph) is mirrored across the mid - ocean ridge, meaning the magnetic pattern on one side of the ridge is the same as the pattern on the other side when reflected over the ridge axis.

Question 2