9 December 2022

Pillbug tracks in ash from Mt. St. Helens

Posted by Callan Bentley

Reader Nancy Weidman (who supplied the Wind River boudinaged basaltic dike images from earlier in the week) sent me this interesting note:

Your ichnoanalogue post reminds me of the insect or pillbug tracks I found in Mt. St. Helens ash deposited in Missoula, Montana. At least some of the tracks, if I recall correctly, ended in dead bugs, presumably dead after its breathing tubes clogged with ash. No fossils from these – the sidewalks were swept clean without a chance to fossilize. The attached photos are from the day after the eruption and are from scanned 35m slides.

So cool!!

Incidentally, this was a momentous moment of my youth – I know what I was doing on this day. I remember coming in from playing outside and seeing that day’s Washington Post in the trash can (this was before widespread recycling) and the bold headline stretching across the entire width of the paper about Mount St. Helens’ eruption. It’s the first “big event” I remember growing up. I guess I would have been 5½ years old? It made an impression on me – I’d never seen a newspaper headline that big before. Maybe something in that moment, mixing the public outreach of journalism and the drama of geology, imprinted itself on me (like these pillbug feet in the ash) and led to this moment, with me geo-blogging!