Deadly hike----Haz-Mat the cause?

[abruzzi]

a bowl of petunias spontaneously materializing somewhere in the troposphere?

Oh no! Not again!

[Drew Wiley]

I'm surprised nobody has suggested an asteroid impact extinction event yet.

[Dugan]

You just did.

[rdenney]

Any possibility of lightning in their area when they were out there? A bolt even into the ground if close enough can cause enough voltage potential between the two (four) feet to stop the heart.

Rick “seems more likely than aliens” Denney

[Vaughn]

Now would that be more or less probable than a sperm whale and a bowl of petunias spontaneously materializing somewhere in the troposphere? FWIW, the science writer Sam Kean maintains that every time we inhale we take in some of the same atoms Julius Caesar exhaled with his last breath.

In every glass of water, there is water that passed thru a dinosaur at some point...if not more than a few times!

[Drew Wiley]

There were no lightning events that low down during the time in question. They're routine in summer afternoons way up above timberline thousands of feet higher; but this was relatively low elevation and halfway into a canyon anyway, where a strike any time of year would be improbable. Besides, anything like that would leave evidence that stood out like a sore thumb. The ground would be charred, probably even a brush fire started under those very dry conditions, and the bodies would have distinct evidence. And such storms don't occur randomly. Everyone in the area would have seen it coming if that had been the case. Lightning storms in the summer reaching clear down to lower elevations are spectacular ridgetop events involving gigantic cumulus clouds and then blackened skies. Thick oak trees get snapped like twigs, and charred. No way to miss those. Lightning doesn't simply happen out of nothing; it's a weather event, and a very predictable one under given conditions. Those conditions were not present.

[rdenney]

Okay. But it’s still more likely than aliens.

Rick “who has seen lightning strike nearby 4-5 miles from where the storm was raging, but yes there would have been evidence, even though charring isn’t the only way lightning kills” Denney

[Drew Wiley]

The lightning storms generally reach their peak in August afternoons. My place was near the edge of the San Joaquin Canyon, south of the Merced River system in question; and I had a view of the pinch point in the canyon - the second highest canyon wall in North America at around 8500 feet deep. This would act like a venturi and channel in the weather, creating a vortex of giant thunderheads (and last year, the highest thermocumulus fire cloud on record).
We'd sit out on the porch watching the lightning. At night one could sometimes read a book due to the flashes being so frequent. On the ridge direct above, one night I counted six large oaks in a row snap after each being hit. Up in the high country itself, lightning storms could be even more dramatic. I've been in so many I can't even count them. There were a couple of linesmen in the community who had taken strikes and lived, both with severe burn scars their whole lives afterwards.

But each summer there were a number of naive hikers in the high country killed. No, burns were not always involved, but at least heart stoppage, and often literal microwave-like cooking of tissues. Regardless, there will be adjacent evidence on trees, rocks, etc. Lighting strike zones are fairly predictable, so I you are looking for a spot to hunker down during a storm, and see a number of charred snags and scarred trees around you, not the best idea to hang around there! The most frequent victims were out in the middle of big lakes in aluminum fishing boats, and didn't take heed in time.

When I was briefly doing my rite of passage summer teenage stint as a cowboy working for a pack station, the office, corrals, and bunkhouse were at 8200 ft, but the actual water tank 2,000 feet higher, connected by downhill galvanized pipe. The owner's wife had just temporarily walked outside the kitchen right when a lightning bolt hit that uphill water tank and sent the charge straight downhill. The whole little kitchen outright exploded. None of us were hurt. Time to replace the pipes with something less conductive!

But we did have alien sightings in those mountains too. Me and my friends made sure of that. Another teenage rite of passage with an exceptionally effective UFO hoax for those days, perpetrated on a true believer society awaiting just such a event atop their supposedly secret sacred knoll in the mountains.

[Lachlan 717]

It’ll be either a murder/suicide or a suicide pact. The dog will be collateral - either a tool of spite if the former or unwittingly part of the pact if the latter.

Occam’s razor at play.

[Drew Wiley]

Yep. Until I know better, I'll continue to suspect a premeditated act. Something could have been slipped into their drinking water, and some of that same water given to both the infant and their dog along the hike around the same time, especially if they avoided nasty water down below, and deliberately kept the dog from it too. Suicide seems far fetched; but domestic murder-suicides do unfortunately happen. I'm more inclined to think they ran afoul of some local or perhaps transient psychopath, who concocted something especially clever and cruel. None of the potential enviro explanations so far seem realistic at all. But plenty of weirdo and narco types are known to occur in the general area.