I know a guy who died from a freak release of H2S at a natural spring. That stuff is immediately fatal when concentrations are over 500-1000 parts per million and concentrations of less than that can make you big time disoriented. It is said at lower concentrations you feel tired so you sit down and breath even more in. Couple that with it being heavier than air, it sinks so sitting down you breath in more concentrated amounts.
Who knows if that is what happened here, but it isn't out of the realm of possibility.
Wouldn't there be dead wild animals all around that area, also?
