I love this story of the mysterious disappearing sinkholes of Indiana's Mount Baldy, where deep pits in the sand dunes are opening and closing for reasons as yet to be determined. These "strange holes" have "appeared since last year, only to collapse and be filled in with sand a day later. Some of the holes were so deep they could not be measured with the researchers' measuring tapes," Livescience reports.
The area has thus been closed to the public while EPA scientists scan the site with ground-penetrating radar; this will help them to develop an "understanding of the overall internal architecture of the dune, using multispectral GPR and coring."
After all, one of the leading theories is actually that buried structures, consumed by the dune's migration over the past century, might have collapsed deep below the sand, creating these temporary sinkholes.
Imagine small buildings imploding under the weight of the landscape, like little cubic tombs held in place all this time by a dry glacier of sand and gravel, finally bursting inward as the strain becomes too much for them to carry—as if, beneath us in weird labyrinths of negative space, the invisible, slow-motion demolition of old buildings proceeds apace, detectable only as momentary pores and sinkholes breathing open and closed in the earth's mobile surface.
(Images courtesy National Park Service).