A Lesson in Abysses

[Image: The title of this post, predictably, comes from Jules Verne: "'Look down!' he cried. 'Look down well! You must take a lesson in abysses.'"].

Those of you near Reston, Virginia, tonight, 4 May, might want to check out a talk sponsored by the U.S. Geological Survey on the "unseen world beneath our feet: caves, sinkholes, and springs."

Sinkholes, we read, are both a subterranean threat of terrestrial instability—glitches in the landscape—and a spatial seed for potential future parks. The talk is free and open to the public, and kicks off at 7pm.