Whitewater Gorge cataclysm

He hoped to find the river again; the air there had been crisp, and he could use a drink of the chilled water to help cleanse him of the noxious fumes that the nearby pools emanated. The sulfur smell clung to his pelt and seemed to mask any residual sea brine that lingered upon him; he didn't notice, but maybe @Yami would, and be driven away by the strangeness of his bad smell. That was about the last thing he wanted; if he lost Yami now, he'd be alone. The last thing Firefly wanted was to be alone.

But the river that rose up to greet him was not the same. The air cleared, but he couldn't see the massive winding river; he moved north along the edge of the chasm and realized why the river appeared to have vanished, as he glanced over the edge and saw - then felt - the rumbling of the water's violent pulse.