Time for another challenge from Artarazzi ... this one is a fingerprint!!

I was wondering what I could do, not getting very far and probably slightly day-dreaming when I started to see depth in the print. Isobars on weather maps? Contour lines on maps? A tunnel? !! yeah!

So here is my tunnell/hole - tree rings and all ... being explored by an intrepid team of ashbseilers.