Deep instability under cohesive wind slab

Cohesive hard slab from surface to 55" down. Got release 55" down after light pressure when column was isolated from the back. When second column was not isolated from the back on our second attempt got release after some light tapping on shovel. Sheer plane bed surface consisted of small surface hoar crystals which formed between the end of the heavy storm cycle and the recent wind event. The release with so little pressure from the top so deep in the pack was frightening in its inference on our skiing future. Our total dig was seven feet plus. Storm Snow deposited below the shear plane was stable.