Well, there is an immense amount of lava, ash and other volcanic debris to be found scattered over a huge area.
Not to mention great numbers of animals preserved in ash. Here’s a site where thousands of animals are preserved in ash from an eruption over a 1000 miles away. http://en.wikipedia.org/wiki/Ashfall_Fossil_Beds
To my mind that constitutes quite adequate verification that something happened.
Physical evidence of what happened in the past, and extrapolation as to the results if something similar happened today. This is quite different from designing a computer model to predict the future and then insisting it be accepted as fact.
By your standard, nothing that happened prior to the rise of modern science could be accepted as fact.
Science is supposed to be observation-based, and what I’m saying is that none of these geologists are eyewitnesses to supervolcanic eruptions, as they call them. There’s certainly evidence of past volcanism, but the cause certainly could be pyroclastic activity of the kind that has been witnessed even in modern times.
BTW, use Wikipedia sparingly; it’s not an authoritative source and relies on external sources for its verification. The article on the Antelope County fossil beds is severely lacking in sources and footnotes and has some unencyclopedic writing.
What he, the original guy that said it did not happen, is not saying is that the earth is only six thousand years old.