One summer day last July, a six-year-old boy was walking across a dune when he disappeared, falling into a deep, narrow hole in the sand. This and two other holes that have since appeared at Indiana's Mount Baldy are unlike anything scientists have seen before—it could be an entirely new geological phenomenon. After being buried for three horrifying hours in the eleven-foot-deep hole, the boy was fortunately rescued. But the incident left an impression on geologist Erin Argyilan, who happened to be doing research at Mount Baldy that day and heard his parents' terrified screams. "I couldn't help in the...