How are the stripes of magnetism on each side of the ridge related?

Answer 1

These stripes, often called Zebra Stripes due to the alternating colors of the original magnetometer readings when the first observations were made. It is directly related to two processes...geomagnetic reversals and seafloor spreading.

Seafloor spreading is easier to start with. Take the Mid-Atlantic Ridge running along the middle of the Atlantic Ocean. It is essentially a gap in the crust through which molten material from the mantle is pushed up through the crust. When it hits the water, the cold water rapidly cools it. As it continues to push out and harden, it very slowly pushes against the tectonic plates running along the ridge, causing them to spread apart. While they don't always run straight through the middle of an ocean, they will occur along plate boundaries. I've seen various maps showing tectonic plates that have arrows to show the direction of movement. Look for spreading ridges wherever you seen arrows pointed apart on these maps.

Now, as the molten material comes out and hardnes, small amounts of magnetic elements crystalize in the rock as it forms, oriented in the direction of the Earth's magnetic field. Consider current rocks forming as stripe 1.

Now, Earth's magnetic field fluctuates. This is normal and usually within small fluctuations. However, at times, it begins to break down. Eventually, when it does, it will rapidly flip over and a new magnetic field will begin to form in the reverse direction. This is Geomagnetic reversal. It used to be believed that it was quite random, though some scientists have argued that there is a pattern to it. It should also be noted that there isn't a specific time frame for how long they last or when they occur. Some will last for a few thousand years, some for a few tens of thousands of years, some for a few hundred thousand years. It varies quite a bit. We are still trying to understand this process, so we don't have definite answers as to what causes the whole process to work.

Now, go back to the seafloor spreading. As the spreading occurs, imagine that a reversal occurs. You begin to see rocks forming with those magnetic fields pointing the other way. Stripe 2. The next reversal will bring it back to what our field looks like now...making stripe 3. And so on. When is the next reversal going to happen...well we don' t have an exact answer. But one estimate puts it between 3000 and 4000 A.D., provided that the current evidence of deterioration continues and isn't a short term effect. Since this is all a relatively new concept, we honestly don't exactly what characteristics we will see when it begins to happen, making it hard to predict. At least not yet.

It should also be noted that the discovery of both seafloor spreading in the 1960's and geomagnetic reversals a bit earlier than that were the major pieces of evidence used to prove the theory of plate tectonics.

Answer 2

The oceanic floor contains "strpies" of rock whose magnetic minerals point to north or south magnetic poles.

Answer 3

No. The magnetic stripes found on one side, which are detected and mapped with the aid of a magnetometer, are considered to be a mirror image of the magnetic stripe pattern of the other side.