In Caverns Below by Stanton A. Coblentz — Read

I have always marvelled that Clay and I lived through the cataclysm. But probably we owe our survival to the fact that the fissure, far from being perpendicular, sloped at an angle of only thirty or forty degrees, so that, while rolling over and over in our descent, we were at least spared a direct drop.

At all events, we finally did come to a stop without receiving any fatal hurt. It may have been minutes, or it may have been hours, before I recovered consciousness; but when at length I came to myself, it was with a dull aching in the head, and with a sensation of soreness in every limb and muscle.