As a Grand Canyon hiker, the Kaibab Limestone formation means excited anticipation of the hike to come on your way in, or simply relief on the way out, knowing that your exertions are nearly over. The rock underneath your feet on the rim, and stretching away from the rim to the north on the Kaibab Plateau, or to the south on the Coconino Plateau, is Kaibab Limestone believed to be 270 million years old. It is estimated that some 8000 feet worth of additional formations were on top of the Kaibab in the geological past, but they have all eroded away except for just a few places in the park, leaving the hard but very porous Kaibab Limestone as the caprock of the canyon.
Since the Kaibab Limestone is very porous, you hardly find running or standing water anywhere on it. Rainwater falling on it quickly seeps down into it, and continues to percolate on down through the entire formation and other porous formations beneath it, only to finally emerge from occasional springs lower down in the canyon. This can make for difficult logistics for long hikes to remote parts of the rim, such as the Powell Plateau, where any water you use for however many days you hike must come in on your back.You get a great view of the Kaibab Limestone formation right near the trailhead of the Bright Angel Trail, looking to the northwest as the rim curves away to Maricopa Point. The Kaibab is the top formation, rounded a bit at the top but then turning into cliffs. The Kaibab Limestone continues on down to the base of those cliffs where the ground starts to slope, marking the start of the Toroweap Formation, with the even steeper and higher cliffs of the Coconino Sandstone below that. This is the pattern you always look for to find the Kaibab in the distance: from the rim look down to the first set of cliffs and down further to their base. Dutton Point at the south end of the Powell Plateau on the North Rim provides another great view of the Kaibab Limestone, with its view of Muav Canyon sweeping off to the north. Kaibab Limestone frequently erodes near the rim into pillars and hoodoos, and you can see some near the center of this picture. Trails usually find a route through the Kaibab Limestone fairly easily, despite its cliffs, since natural breaks in the cliff are usually not too far apart. Here the South Kaibab Trail drops swiftly through the Kaibab Limestone on a set of tight switchbacks that are easily negotiated, but only because the engineers that built the South Kaibab Trail in the 1920’s blasted into a nasty cliff to create them.
Many trails pass though the Kaibab Limestone very quietly, with no cliffs present at all. These trail sections will commonly wander through the trees, like here on the Waldron Trail, with distant views blocked until the trees clear out in meadows on the slopes of the Toroweap Formation. The tops of the Tanner and New Hance trails through the Kaibab are like this, with short but steep switchbacks that are wonderfully cool on their shaded, north-facing slopes in the summer, but become treacherous when covered by snow and ice in the winter, when, if you are sensible, you will wear crampons or ice cleats on your boots.
To read more detailed geological information about the Coconino Sandstone, visit the United States Geological Service page for the Kaibab Limestone.