Cosmic rays are produced from massive galactic events like a supernovae and consist of matter particles like Fe or Mn that have additional neutrons making them radioactive.
The explosion accelerates the particles to nearly the speed of light. If the SN was 10,000 light years away it would take about 10,000 years for the particles to get here. In addition because they are traveling at nearly the speed of light they would not appear to “decay” relative to our Earth clocks which are at rest.
Once the particles arrived at the Earth and came to rest they began to decay. From the known half-life of these isotopes that was about 2.6 billion years ago.
There is growing evidence it was a micro nova from our sun.
said, "Cosmic rays are produced from massive galactic events like a supernovae and consist of matter particles like Fe or Mn that have additional neutrons making them radioactive"
This has not been studied that I'm aware of. The two major near extinction of humans bottle necks of human population of 70,000 years ago and 12,800 years ago also had the effect of a Y Chromosome(Males) bottleneck right after the both events. Y Chromosome are more radiosensitive then the X chromosomes. As a result for thousands of years after both these events the female/male ratio was 6 to 1 and 17 to 1 respectively.
I'm suggesting a micro-nova from our sun could be that trigger.
million y.a.
Okay, thanks. I have not heard of particles of matter travelling at nearly the speed of light///