How can scientist tell that earth's magnetic field sometimes reverses direction?

Answer 1

You don't have to be a scientist to observe that fact. All you have to do is take any magnet

and hang it up on a thread, so it's free to rotate and point wherever it wants to point.

When you do that, you find that every magnet that's free to turn always turns to point at the

same place ... a spot in far northern Canada.

When you do this experiment with thousands of magnets in thousands of places all over the earth,

and keep records of the direction that magnets point in various places, it all goes together to give

a beautiful diagram of the earth's magnetic field.

People who do a lot of traveling over long distances have used this fact for thousands of years to

build a device that helps them find their way around the surface of the earth. The device is called

the 'magnetic compass'.

Answer 2

Scientists can tell that Earth's magnetic field sometimes reverses direction by studying the magnetic orientation of rocks that have solidified over time. These rocks contain minerals that align themselves with Earth's magnetic field at the time of their formation. By analyzing samples from different geological layers, scientists are able to identify periods when Earth's magnetic field has reversed direction.

Answer 3

The reversals of magnetic polarity are recorded most prominently in the basaltic rock of the seafloor. As rising magma at the mid-ocean ridges starts to cool, the magnetic minerals in the magma act like compass needles and become locked in their alignment to the magnetic pole. When there is a reversal or shift in magnetic polarity, magnetic minerals that are present in the new crust forming magma become aligned in a different direction. Rock core samples have confirmed that the direction of these minerals that are frozen in rock have changed directions numerous times in the geologic history of the oceanic crust.

Answer 4

The allignment of ferromagnetic minerals near tectonic boundaries.

As new rock solidifies from magma, the earth's magnetic field acts on them causing a pattern fo appear.

As you move from the fault (where they emerge), they face North, then South, then North again; implying that the magnetic field changes alignments every few hundred thousand years.

Answer 5

Scientists know that the magnetic poles have reversed many times because when scientists put periods into normal polarity and reverse polarity in chronological order, they discovered a pattern of alternating normal and reverse polarity in the rocks. hope this helps :)

Answer 6

Some volcanic material contains elements or compounds which are magnetic. When molten, the molecules of these materials are free to align themselves with the earth's magnetic field. But when these volcanic rocks cool, and solidify, their magnetic orientation is frozen. A study of such rocks has shown that the earth's magnetic field does reverse polarity from time to time (or between chrons).

Answer 7

Yes, hundreds of times over the last 1 billion years. It is in the process of flipping now, but may take one thousand years to do so.

Answer 8

Pottery when fired retains the direction of the magnetic field when cooled. Thus we can detect the examining the direction of the field in the pottery.

Answer 9

Magnetic compass always show south and north direction and not any other, round the year, that's why earth has magnetic field.

Answer 10

They have found the fossils of tropical plants in the polar regions.