A park ranger should be able to

They [park rangers] will be needed on the trail. Once we outlaw the motors and stop the road-building and force the multitudes back on their feet, the people will need leaders. A venturesome minority will always be eager to set off on their own, and no obstacles should be places in their path; let them take risks, for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches–that is the right and privilege of any free American. But the rest, the majority, most of them new to the out-of-doors, will need and welcome assistance, instruction and guidance. Many will not know how to saddle a horse, read a topographical map, follow a trail over slickrock, memorize landmarks, build a fire in the rain, treat snakebite, rappel down a cliff, glissade down a glacier, read a compass, find water under sand, load a burro, splint a broken bone, bury a body, patch a rubber boat, portage a waterfall, survive a blizzard, avoid lightning, cook a porcupine, comfort a girl during a thunderstorm, predict the weather, dodge falling rock, climb out of a box canyon, our pour piss out of a boor. Park rangers know these things, or should know them, or used to know them and can relearn; they will be needed.

Edward Abbey, Desert Solitaire, pp. 69-70 (Ballantine paperback ed.) See also Robert Heinlein.