Grand Canyon trails like the Hakatai Shale. Within the sequence of Grand Canyon Supergroup formations, the Hakatai is immediately below the Shinumo Quartzite, which forms high, sheer, impenetrable cliffs, and is just above the Bass Formation and the Vishnu basement rocks, which also are cliff forming and are difficult to navigate through. The Hakatai, though, is mostly soft and crumbly, and forms gentle slopes. And, since the supergroup formations are tilted and are frequently broken up by fault lines, trails can navigate up or down through a section of supergroup formations by following the Hakatai.While outcrops of Hakatai appear in scattered areas of the inner canyon, the Hakatai makes one large appearance within the big sequence of supergroup formations in the eastern inner canyon, the sequence stretching from where it first emerges just downstream from the mouth of the Little Colorado River, to where it finally pinches out below the Great Unconformity in the vicinity of Horseshoe Mesa. The Hakatai first appears within this sequence just upstream of this spot at Hance Rapids, at the foot of the New Hance Trail. Here, like nearly everywhere it appears, the patches of lurid red-orange within it make it easy to identify. From Hance Rapids, two trails follow the Hakatai for quite some time. The New Hance Trail follows the Hakatai for two miles, as it wanders up a creek bed on the floor of Red Canyon, named precisely for the red slopes of Hakatai Shale that form the base of its walls. Here the New Hance trail is at the point where it is just climbing up from the creek bed, following the band of Hakatai up between cliffs of Shinumo Quartzite above and stair-step cliffs of the Bass Formation below. The other trail following the Hakatai up from Hance Rapids is the Tonto Trail. While the Tonto Trail is up on the Tonto Platform for most of its hundred mile length, its first few miles slowly climb up from the Colorado River following a platform of Hakatai Shale. Here we are in the Hakatai about a mile downstream from Hance Rapids, following the steady upward slant of the Hakatai that you can clearly see in the sequence of supergroup formations across the river. From here the Tonto Trail continues to follow the Hakatai as it curves back into Mineral Canyon, finally reaching the Tonto Platform though a break in the Tapeats Sandstone after about another three miles. The South Kaibab Trail is an excellent example of a trail finding a way through using the Hakatai. The trail follows a very complex set of faults that have scattered chunks of Hakatai over a thousand vertical feet, starting right where the trail penetrates the Tapeats Sandstone cliffs at the Tipoff, and continuing on down until near the Colorado River. This first picture is from the Tipoff, and you can clearly see the trail curving through the red-orange Hakatai down to a big residual block of Shimuno Quartzite, which the trail curls right around within the Hakatai and continues its easy descent on the other side. This second picture along the South Kaibab Trail is from another viewpoint further down, looking back at the descent of the trail through the Hakatai. In the upper right-hand corner is the same big residual block of Shinumo seen from above in the first picture, and beneath it is a tongue of Bass Formation that one of the many faults in the area has shoved up above this spot. But this spot is at another, lower boundary between the Hakatai and the Bass, and if you look on the left side of the picture you can see where the trail continues on down further within the Hakatai for several hundred feet further, through yet another, lower chunk of Hakatai, created by yet another fault. The North Bass Trail also follows the Hakatai for a time, first right along Shinumo creek and then up and over a saddle on the way to the Colorado River. This spot is in the Hakatai on the way up to that saddle, looking back down towards Shinumo Creek. The hillside on the other side of the creek shows a fine cross-section of the Grand Canyon Supergroup all the way from the Dox Formation on top to the Bass Formation at the bottom, and the Vishnu Complex below it. You can also clearly see a pair of fault lines (the black lines) dramatically cutting though and offsetting the formations.
To read more detailed geological information about the Hakatai Shale, visit the excellent Wikipedia page for the Hakatai Shale.