re: From far away, the layers look like tuffs, but
... close up, there's 'hardly' any vesicles/pits in the exposed layers. The suface texture looks smooth and slick even with the 'bubble'(be they pepperites, pisolites or accretionary lapilli) features. IMHO, from looking at some of the spiked edges, it looks as if this finally came in contact with water or a cool, moist atmosphere.
No wonder this one took you to the caves, R.L. :)
I haven't been able to find really close up photos of hydrovolcanic tuffs on Earth.