The very dangerous sink hole, about 30 feet in diameter and at least 25 feet deep that was discovered on the San Rafael in April has now been filled. It was determined to be an old mine shaft which water had gotten into and caved in creating a hazardous hole to the surface.
A group of off highway vehicle riders found the hole and notified the Bureau of Land Management, who controls most of the land in the San Rafael. The BLM fenced the area to prevent anyone from getting close and it was just recently filled.
Sink hole is no more
"The large gap in the Swell was discovered by ATV riders."