By analyzing the remanent magnetization, geophysicists have determined that the modern magnetic era began 780,000 years ago. It was named after the French physicist Bernard Brunes, who in 1906 discovered the thickness of lava flows with reverse polarity. This discovery caused a sensation, but the sixties did not find practical application.
Then there were many other rocks with reverse magnetization. The paleomagnetic geochronological scale was set according to their ages. Now it is used to date many rocks, the age of which cannot be determined by any other method, except by using the direction of remanent magnetization on them.
Impressive results have been studied by this method in the study of basaltic layers on both sides of the mid-ocean ridges. Here rocks with normal reverse polarity were located, alternating, in parallel in themselves relative to the axis of the ridge. This indicates the constant formation of the oceanic crust and the spreading of the ocean floor, confirming the theory of continental drift.
The paleomagnetic scale demonstrates that the polarity of the magnetization of rocks does not change over a period of several hundred thousand to a million years more. Then there are sudden versions of the field. There are also episodes of short-term reversals, when the polarity reversal process takes place for several thousand years.
A French-American group of researchers found a kind of record: the analysis of basalt samples, which is 16 million years old, showed that the magnetic poles then shifted by several degrees every day! This means that the inversion was completed in a matter of months, and maybe even weeks.
During inversions, the magnetic poles move along the meridian, in particular through the North and South America. Before and during such a migration, the magnetic field weakens and at times can become chaotic, as if the Earth had several poles at once. Its noticeable weakening is taking place now.
Shining sky
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One of the most amazing and fabulously beautiful natural spectacles is the iridescent stripes of red, green and yellow light in the sky of high latitudes - the so-called polar lights. It can be both northern and southern. For a long time, theorists from ufology associated it with the appearance of UFOs.
However, everything has long been explained from a scientific point of view. This atmospheric illumination is caused by free protons and electrons. Flying from the Sun at a speed of about 1600 km / sec, they collide with air molecules and atoms at altitudes of 80-1000 km.
When particles collide, energy is released in the form of light. Most often, the aurora is observed in a radius of 23 ° around the magnetic poles, since they act as traps that attract elementary particles to themselves as they approach the Earth.