While skinning on the Garden City Ridge, I heard a whoomphing and saw cracks shoot just below the ridgeline. I was 75 feet west of the main Garden City bowl. The terrain below me was between 28-30 degrees, so cracking and buckling was the only result. I followed the cracks and buckles along the ridgeline. About 600 feet from the initial cracking, I could see that I had sympathetically released a small soft slab on a 32 degree rollover about 100 feet off the ridge.