Is there any evidence of large meteors striking Montana like in Idaho or Arizona?
Evidence for at least one meteorite impact is known to exist in southwestern Montana. It is very interesting because the evidence is contained in rocks that are about 1.4 billion years old, and the impact is thought to have happened about 900 million years ago. Since that time, these rocks have been squeezed, pushed, broken, pulled apart, pushed together, and eroded, so that nothing that looks like a meteor crater is present. Interestingly, the actual impact may have happened in Idaho and then millions of years later tectonic forces pushed the rocks into Montana. So, after all this, what is the actual evidence for an impact there? Large impacts sometimes create structures called shattercones in the rocks at the impact site. To the trained eye, these structures are distinctive, and look like those found around more modern and well-documented impact sites. So, no crater, but there is a smoking gun.
