There are No "Natural" Occurrences
This was one of Hashem's many kindnesses and warnings, giving that generation every opportunity possible to wake up and do teshuvah before it would be too late.
Yet what was their reaction?
"It doesn't mean anything. Apparently, it's just a coincidence."
"I heard that once every few hundred years, the Earth changes its orbit," said another one of the cartoon skeptics. "Come on, let's hurry up so we won't be late to the party."
But it doesn't mean that the occurrence doesn't mean anything.
Even with something as predictable as a solar or lunar eclipse, the eclipse still contains a message for us.
So it's true that the Earth cycles through warmer periods and cooler periods.
It's true that the Sun also undergoes changes and cycles.
But these cycles aren't exact to the day or year.
So the question becomes: Why davka now and with these specific consequences?
The same goes for hurricanes, volcanoes, and everything else.
Chazal informed us millennia ago of the different punishments for different sins. Death by fire, choking on volcanic ash or drowning all mean something.
Scoffers will continue to insist that it's man-made global warming.
But Rivka Levy repeatedly brought evidence (the most recent discussion now found HERE) that undersea volcanoes are waking up. And indeed, we see that land volcanoes are also waking up.
The question is why?
Not what geological or astrophysical changes are causing it, but what Hashem wants to warn us about via ash, lava, hurricane winds and flooding storm surges, and earthquakes.
He loves us and wants to give us this time for soul-searching and self-improvement.
One Single Continent
Of course, if you understand that the world once consisted of a giant landmass, making all regions accessible to all people and animals, then such carvings make sense. Either hippos and rhinos transversed that way pre-Mabul or else people who'd seen such animals decided to etch their memories into the cave walls.
Either way, it's not PROOF of the Torah's version of pre-Mabul geography. It's not like there's graffiti: "Hi-ho, hi-ho, it's off to Noah's Ark we go!"
(Those of us who are not "scientists" understand that indications, assumptions, and personal beliefs aren't substitutes for proven evidence.)
But it does fit in to the Torah's narrative.