Question

how do magnetic stripes of iron in ocean rock provide evidence of seafloor spreading?
they show when earths poles reversed.
they show how the density of the seafloor has changed.
they reveal a matching pattern on either side of the ridge.
they reveal differences in the mineral composition of newly created rock.

Explanation:

Seafloor spreading occurs at mid - ocean ridges. As new magma rises and cools, it records the Earth's magnetic field at that time. The magnetic stripes (normal and reversed polarity) are symmetrically distributed on either side of the mid - ocean ridge. This symmetry shows that new oceanic crust is being formed and pushed away from the ridge at a relatively constant rate on both sides, which is a key evidence for seafloor spreading.

• Option 1: While the magnetic stripes do record pole reversals, this alone does not directly prove seafloor spreading.
• Option 2: The magnetic stripes are not related to changes in seafloor density in the context of proving seafloor spreading.
• Option 4: The magnetic stripes are about magnetic properties, not mineral composition differences (which are not relevant to the main evidence of seafloor spreading).

Answer:

They reveal a matching pattern on either side of the ridge.