On 7-30-15 a report of rock down, but no indication of a fall above the anchorage of the bolts, until 8-10-15 at which time it was reported as a roof fall. Weathering was the cause of the fall. The area was bolted with 8' bolts with resin at the anchorage point. The fall is approx. 35'L X 16'W X 9' in height. It did not obstruct ventilation.