Not so happy valley

We sledded into gorge 15km, climbed to happy valley on an un-breakable crust. Dug a pit at 2000m, north aspect, 37 degree slope. Total depth 125cm. Results: ECTP13 and CTE (on3). Both tests had a sudden planar collapse down 40cm, and the blocks slid off onto our laps. We skied down the uptrack.