Anthony's Map Key
All my dungeon maps will use a universal key, presented here for your convenience.
This symbol represents a change in elevation, with the lines radiating out into the lower elevation area. The number indicates how sheer the elevation change is. A drop of 5 ft. is probably a gentle slope akin to what you would see with typical contour lines. A drop of 40 ft. or 50 ft. is more like a cliff.
This symbol represents a sheet of ice. Ice is not necessarily difficult terrain, but movement on ice is halved, and taking a standard action requires a reflex check (DC 10) to avoid being knocked prone. The lines radiate out into the area covered by ice, and the filler waves serve as a reminder that you are, in fact, moving over ice.
This symbol represents water, with the lines radiating out into the area covered by water. Additional contour lines paired with numbers indicate the depth of the water, and an arrow indicates the current of the water, if any.