Why do rocks on the ocean floor form a pattern of magnetized stripes?
The rocks contain iron that points in the direction the rocks move away from the ridge.
The rocks are composed of different materials depending on when they formed.
The rocks change shapes as a result of the pushing and pulling of seafloor spreading.
The rocks contain iron that points in different directions depending on Earth's polarity.
The correct answer is: The rocks contain iron that points in different directions depending on Earth's polarity.
The pattern of magnetized stripes on the ocean floor is known as magnetic striping or magnetic anomalies. It is caused by the movement of tectonic plates, specifically through a process called seafloor spreading.
As new oceanic crust is formed at mid-ocean ridges, molten rock called magma rises from the mantle and solidifies to create new crust. This process also allows for the formation of new rocks loaded with iron-bearing minerals, such as basalt.
These iron-bearing minerals align themselves with Earth's magnetic field as they cool and solidify. The Earth's magnetic field is not constant and periodically reverses its polarity over geological timescales. The polarity refers to the orientation of the magnetic field.
Therefore, as the newly formed rocks cool and solidify, the iron minerals within them align with the prevailing magnetic field at that time. This creates a pattern of magnetized stripes on the ocean floor, with alternating bands whose magnetization is directed parallel or antiparallel to the present-day magnetic field.
By studying and dating these magnetic stripes, scientists have been able to confirm the theory of plate tectonics and develop a timeline of Earth's magnetic field reversals over millions of years.