Scientists: More holes found in Mount Baldy

CHICAGO (WLS) -- Scientists have found more holes in Mt. Baldy, the sand dune where a 6-year-old boy was buried alive in July 2013.

Researchers have found seven holes underneath Mt. Baldy's sand. The one that trapped Nathan Woessner is the biggest, they say.

Officials have yet to determine what led to the collapse, but believe the holes are caused by trees and other debris. The Indiana dunes have migrated about 120 meters in 70 years, which means they've moved on an area where there were once homes and vegetation. Scientists said cameras that can look under the surface of the sand will help in the investigation.

Woessner, of Sterling, Ill., was trapped for three hours, but survived due to an air pocket.

Mt. Baldy is closed indefinitely.

The National Park Service is behind the $90,000 investigation.