Cambrian explosion

Earth’s magnetic field is a crucial element for the comfortable life of species on the planet. It reliably protects life from the effects of cosmic radiation and other factors. About 550 million years ago there was a sharp jump and the magnetic field weakened sharply, after which it regained its strength.

Scientists assume that the processes that led to the Cambrian explosion were at the center of the Earth – a sharp leap in the formation of new life forms unrelated to those that existed before.

Analysis of crystals in Quebec rock has shown that during the Cambrian explosion, Earth’s magnetic field strength was about 10% of what it is today and could not adequately shield living organisms from cosmic and solar radiation. Most likely, the magnetic field was losing its strength due to the rapid cooling of the core.

Over time, the core began to harden. This triggered the movement of the outer core and restored the strength of the planet’s magnetic field. As the study showed, the formation of the inner core took place just before the Cambrian explosion began – a sharp increase in the number of living things on the planet and the appearance of many exoskeletons.

Observations of other worlds where magnetic fields are lost show the dramatic consequences of the loss of the protective magnetic envelope. An example is Mars, which lost its magnetic field 4 billion years ago. Without protection from the solar wind (the constant stream of protons and electrons flowing from the Sun’s surface), the Martian atmosphere evaporated into space, leaving the planet’s surface dead and dehydrated.

How and why the Earth’s solid iron core began to form remains a mystery. But in half a billion years it had grown to the size of the moon, and without it our planet would now look different.