That is the working theory of a team of scientists who are scrambling to figure out how and why the boy was buried under 11 feet (3.4 meters) of sand for 3.5 hours on June 12, 2013. The fine, silky grains dropped out from under him as he explored Mount Baldy, the most popular destination at the national park about 60 miles (96.6 kilometers) southeast of Chicago.

As a result, scientists are using ground-penetrating radar that shoots as far as 75 feet (22.9 meters) below the dune's surface to build a detailed, three-dimensional map of trees, buildings and more that could be buried there. They're also combing old aerial photos and historical records for clues to what is hidden beneath the