image BXO48.jpg
track, Sadgill to Gatescarth, Longsleddale, Westmorland, NY40 -- Rock, hand specimen of a igneous rock, Andesite lava with vesicles, from the track from Sadgill to Gatescarth Pass, Longsleddale, Westmorland, 2012.
Ordovician? Borrowdale volcanic group.
The vesicles are gas bubbles which came out of solution in the lava when pressure reduced as it erupted from the volcano (like bubbles in lemonade).
(photo . .2012)