Collapsing and Cracking on Black Mtn, N Madison

While touring up black mountain on Saturday, February 15th 2020, our group heard very loud whoofing on flat ground, collapsing large areas. There was small cracks formed but we were on very low angle slopes. We switched to a back-up plan to get down. A second large whoofing occurred minutes later a short distance away from the first. This time we could feel the snow drop below us by a few inches. We turned around and followed our tracks down. We dug two pits in the vicinity of the collapsing. Two extended column tests produced failures on the same depth hoar at the ground, ECTP 23 and ECTP 16. The latter result was on a pit of at least a meter deep. WE collapsed another flat while skiing down. No other obvious signs of instability were seen.