I do not believe we have anything equivalent to "quick sand" in PA, but if you ever, as I have, feel yourself sinking by your own weight into muck, lay down on your back or chest or side. As soon as you make this shift of weight, your feet will begin to rise to the surface. It may be slow at first, but it is scientifically required that this will happen, even if the muck is the consistency of a hearty soup. Logic will carry you from there.