McPhee decoded

John McPhee drops a Celtic allusion into The Control of Nature to describe the severe hazard along the lower Mississippi. From the “Atchafalaya” section:

This threat to navigation could be called could be called an American Maelstrom—a modern Charybdis, a Corryvreckan—were it not so very much greater in destructive force.

The whirlpool in the Gulf of Corryvreckan, off the west coast of Scotland, is better known by Britons than by me. Fans of the Powell-Pressburger films should know it, too.

On the other hand, this word looks like a McPhee nonce. It appears only one place else online, in a Jstor-protected source.

Wells fills a dish with a dark soil from burned chaparral. He fills the eyedropper and empties it onto the soil. The water stands up in one large dome. Five minutes later, the dome is still there. Ten minutes later, the dome is still there. Sparkling, tumescent, mycophane, the big bead of water just stands there indefinitely, on top of the impermeable soil. (“Los Angeles Against the Mountains”)

Presumably the sense of mycophane is “semi-transparent, like threads of mycelium.”