One day the slope is there; the next day it's gone. A gaping 100-foot-deep rift appeared overnight on an expert run at Great Divide Snowsports in Montana, causing the run to be closed for the remainder of the season.

A ski patroller on a routine run last Monday found a giant chasm on skier's right of the double black diamond Huckleberry Hill Run. The 10-foot-wide hole shot 30-to-40 feet downhill. The rift's vertical walls plummeted 80-to-100-feet deep.

The cavernous hole, most likely resulting from an earthquake last weekend, wasn't the first one to appear at the ski resort, nor the largest. Chain link fences surround two other similar holes in the same area at Great Divide. The holes come from old mine shafts from the 1800s.

"There's probably a total of a dozen (holes) out there," owner Kevin Taylor told OnTheSnow, referring to Great Divide's 1,600 acres. "The place is like Swiss cheese. On cold, clear winter days, you can see steam rising out of vents."

Taylor found the largest chasm in the summer of 1999 when he was developing the Wild West terrain. "It was a really hot day, and this big blast of cold air hit me," he said. "It was 40 feet across and 800 feet deep."

The resort enclosed the new rift with reinforced snow fencing and put up warning signs to alert skiers and snowboarders to stay away from the perimeter.

But for Great Divide skiers and riders, another open mine shaft is nothing new. "It's not a big deal, but I was worried about revealing it in case it aroused curiosity to the point where people would go look," he said.

Great Divide issued a statement to temper the enthusiasm of inquisitive skiers and snowboarders: "You cannot see into the hole from outside the perimeter, so please do not let your curiosity get the best of you and go inside the fence to get a better view. That is dangerous." The danger comes not only from the steep pitch of the chasm's walls, but also because the overhanging surface soil could give way.  

The Montana Department of Environmental Quality Abandoned Mines Division plans to fill the chasm at Great Divide this summer. The agency may use a new technology to stabilize the hole by filling it with a giant foam plug and resurfacing with soil.

The run is expected to re-open for skiing and riding next winter. Other parts of Huckleberry Hill and the adjacent Snaggletooth Cliff area are still open for advanced and expert skiers this winter.

Great Divide, despite its new geologic feature, has amassed a snow pack that should last well into spring skiing. "It's an excellent snow pack. The warm spells just compress it, so we're skiing on a glacier right now tilling in fresh snowfall," said Taylor. "March and April suns will have a hard time working it over. We'll be skiing in May this year."