Indiana Dunes: Mount Baldy Remains Closed as Investigation of Mysterious Holes Continues [VIDEO]

Mount Baldy will be closed indefinitely for further investigation of the mysterious holes that appear and disappear suddenly.

The National Park Service announced this Sunday that Mount Baldy at the Indiana Dunes National Lakeshore in Michigan City, Ind., will be closed indefinitely for public safety as two additional mysterious holes have cropped up since July. The cause of the depressions and holes remains unknown. Additional research is needed to determine the reason behind the phenomenon.

In the last 10 months, geologist Erin Argyilan analyzed the sediment particles, wind patterns and also mapped the terrain but this didn't help solve the mystery surrounding the holes that appear and vanish in the sands of Mt. Baldy.

The north side slope of the Indiana Dunes National Lakeshore will be closed , Washington Post reports.The authorities plan on closing the parking lot, trail, and beach in front of the dune. Also all vehicular and pedestrian access will be curbed during investigation for safety purpose.

"Mount. Baldy is one of the most visited sites in the national lakeshore, attracting thousands of visitors each year," acting Superintendent Garry Traynham, said in a statement. "But the continued development of these holes in the dune surface poses a serious risk to the public. Our first obligation must be to the welfare of our visitors who are here for an enjoyable outing."

The first hole surfaced in mid-July and swallowed a 6 year-old-boy who was later rescued from under 11 feet of sediment. The second hole appeared in August that was about 10 inches wide and 5 feet deep. During the ongoing investigation, the team spotted two additional holes and several depressions. The holes are short lived and remain open for less than 24 hours after which they  collapse into the surrounding sand.

Even ground penetrating radar and specialized GPS devices have failed to solve the puzzle.

The team is now gearing up for a more comprehensive investigation of the dune, which includes mapping the openings, depressions and anomalous features, use of multispectral Ground-Penetrating Radar and coring to understand the internal architecture of the dune.

However, the researchers speculate that the decaying trees beneath the sand are to be blamed for the sudden formation of holes and depressions. Also human activity has led to the erosion of the dune , which is shifting away from the lakeshore burying old trees in the process. Experts believe the rotting trees underneath are causing the holes.

"This particular dune has a complicated history," geologist Erin Argyilan told Washington Post.

The good news is that the mysterious holes are unlikely to appear at the other end of sand dunes that are kept in more natural state.