Unfortunately it is a little short on detail, other than fern spores below a metre of dirt, more detail about the soil content... Ie rare metals in the first layer, lead them to the conclusion it was an impact event.
Given the detail.... This could have been the result of a bushfire , flood or any natural reason.....
Interesting article there Ron, but it was a bit thin on the detail (mind you it's only a news report). However, they've suspected a multiple strike cause for quite some time. There's precedence for it to be found not only here on Earth but also elsewhere in the solar system....especially on the Moon.
I'll see if I can grab the journal article in question and post it here (or at least the abstract).
So they believe the 'new' one occurred first, several thousand years before the Chicxulub impact. So how big was the Ukraine impact - big enough to cause extinction? How do they know the second layer was the result of the Chicxulub impact and not another, closer impact that they have not yet discovered? We only need to look at the moon to know that the earth had to have been bombarded at some point(s) in the past, the fact that we have only been able to uncover a handful of craters doesn't really tell us much!
It's only small....24km....probably only a 500KMT to 1MMT impact. Maybe some local extinctions, if lucky. Unless it was pure Iridium, it wouldn't have produced enough of it to create the Iridium layer in the clay member at the KT boundary.
Double meteorite killed the Dinosaurs
