A roof fall was discovered at north G., 2,1/2 x-cut. #0 hdg. Fell above the anchorage 18' wide 7' high, do not know how long. 6' super twist bolts and 12' post tensioned cable bolts were in use. No men or machines were injured or trapped, no ventilation or travel was affected. This fall was 2,800 feet out-by the section loading point.