At the end of a trail i walked, there was a small hill going down - it looked like water or somthing like motor oil covering the path, did'nt behave like the mirages i've seen on roads ect. came directly up on it and nothing there. observed the mirage at aprox. 4 ft. away, tryed to dupe. the situation again - did'nt work. this was seen not only by myself but also by a friend with me. very confusing because this happened at night with heavy tree top cover and very very dark ???????????? any conclusions

Maybe because the tree shadow is on the floor but when u arrive there the angle that u look would be different!!!and because its at night u may have mistaken it as a puddle of water