Those claims have been thoroughly debunked. Among other things, they submitted their samples to a lab that explicitly said their techniques were no good for rocks younger than 2 million years.
Thank you for those links! I really did not feel like digging around for the actual facts regarding that claim about Mt. St. Helens—being a life-scientist, I do not have facts about geology floating freely within my head, so I would have to look up any rebuttal material. And, being a life-scientist, I spend much of my work time doing literature research within my field; when I come home, I want to relax, not engage in more literature searches.