No lantern here guys. I figured my family would have one so I didn't buy it at character creation. That and I fight with two swords, so it would hamper my fighting style.
Light Sources from your character sheets:
Common Lamp - Kiylea, 1 flask of oil, 6 hrs. total, 15 ft. radius
Light spell - Ringly, 10 min. per casting, 20 ft. radius
Bullseye Lantern - Alton, 5 flasks of oil, 30 hrs. total, 60 ft. cone
Just a note, running water over granite, not likely to leave anything sort of like tracks even if something did come out of the crevice. Kiylea at the least would know that it'd be futile to check.