The following is a transcript of the narration for this panorama. To listen to the narration, enter the project at this location and press the play button.
I love this panorama spot for its sheer beauty. The Colorado River running muddy, and above it, facing use across the river, one colorful layer after another of the Grand Canyon Supergroup formations, dramatically slanting downward from left to right. And below the supergroup formation, we see the Vishnu Complex basement rocks making their very first appearance, forming the beginning of the Granite Gorge, which will confine the Colorado to a tight, narrow inner canyon for many river miles to come.
The highest layer within the supergroup we see across the river from here are the sheer brown cliffs of the Shinumo Quartzite. As the softer, reddish Hakatai Shale erodes away and undermines the Shinumo, giant blocks of the hard quartzite calve away and tumble down the slopes of the Hakatai, including the jumble of boulders that surround us right here.
Across the river, bright red splotches of the Hakatai peek through in spots, and the spot where we standing right here is in the Hakatai. The Hakatai slants up from the river on this side of the river as well, and the Tonto Trail, which began back at Hance Rapids less than a mile from here, uses it as a ramp to rise up from the river until it reaches its usual place up on the Tonto Platform 3 trail miles further west.
Below the Hakatai Shale is the Bass Formation, the lowest and oldest formation with the Grand Canyon Supergroup. I think the fluted, reddish brown cliffs in the top portion of the Bass Formation are stunningly beautiful as we look across the river to them from here, but it is the history embedded within lower layers within the Bass intrigue me. About 1 billion years ago, dark sills of Cardenas Lava pushed their way into the Bass Formation, then already 200 million years old, and the dark, black band we see here is one of those sills. When the hot lava came in contact with limestone layers within the Bass, it cooked the limestone and turned it into asbestos, and it is asbestos that forms the white splotches you can see scattered along the edges of the sill.
Look closely near the base of the sill and you can make out bits and portions of a trail. In the late 19th and early 20th centuries, miners followed the trail, which stays close to the bottom of the sill as it rises up to the west, and eventually curves around into Asbestos Canyon, where most of the mining of asbestos took place. Only a few tons of asbestos were ever mined, and to reach market it had to be hauled on mules back down the trail to the river, then ferried across the river in small boats, then hauled again by mule up to the rim, then hauled some 70 miles by wagon to the railroad in Flagstaff, and then finally loaded onto a train. As in the case of nearly all early Grand Canyon mining operations, no great fortunes were made.
Heading east on the Tonto Trail from here, we will travel about half a mile, about half the distance back to the start of the Tonto Tail at Hance Rapids, to a panorama spot just across the river from where the Bass formation first rises up from the water.
Heading west on the Tonto Trail, we travel a short distance further up the Hakatai Ramp to another fine view of the supergroup layers across the river, and where the trail first begins its swing back into Mineral Canyon, which it winds its way through for a couple of miles on its way up to the Tonto.