Some boulders seen on the trail to Helen Lake sported lovely sets of Skolithos trace fossils. Here are two boulders, with the perspective on the tubular paleo-vertical Skolithos burrows being “map view”:
Another boulder, in the middle of the trail, showed them in a fine cross-sectional view:
(click to enlarge substantially)
It also included some interesting “ribbed” vertical traces that I didn’t recognize as familiar:
…Diplocraterion, perhaps? Seems too “linear” and not curved enough for that, though. They are about 3 or 4 times as thick as a “typical” Skolithos, which I would say is 3-4 mm.
Skolithos are more likely Arenicolites – paired tubes in the first two surface views of the boulders. I think you’re right about the Diplocraterion in the bottom couple of pics.
Once again, you show that geologists have all the fun.
I saw some skolithos in river boulders outside of Lake Louise. You can find the “ribbed” (annulated) skolithos in the Zabriskie Quartzite in Death Valley as well. Nice pictures!