[Rebelbase]

How do micro grains of iron traveling a bazillion miles per hour survive re-entry into the Earth’s atmosphere?

[amorphous]

I've read actual micro grains of iron have been found in tusks and surviving bones of large mammals which once roamed North America. Scientists claimed to have even been able to determine the actual direction these micro grains traveled from and when the animals died by radio carbon dating. As to how these iron grains penetrated the atmosphere, there were a lot of them and they were traveling extremely fast.

I recommend the following book which goes into greater detail:

The Cycle of Cosmic Catastrophes: How a Stone-Age Comet Changed the Course of World Culture Paperback – Illustrated, June 5, 2006 by Richard Firestone (Author), Allen West (Author), Simon Warwick-Smith (Author)

It's available on Amazon.