the Great Unknown), I sent one text from camp the first night (surprise, cellular coverage at mile 6!), and on the second or third night I had a two-minute conversation on the emergency satellite phone (we couldn't download a waiting message on the phone so we each checked on our loved ones; it turned out to be a "Welcome to Verizon" message or whatever satellite company it was). I had seen not a single sign of any sort since we left Lee's Ferry aside from some number markers on the Unkar Ruins trail. So the beginning of our day was a real culture shock. Less than a quarter mile from our camp at Cremation, a bridge came into view!
And...there is green stuff all over the place, in spite of the 100+ degree temperatures that last all through the summer season. Cottonwood trees and grass and stuff. It turns out that Phantom Ranch was located along Bright Angel Creek, one of the larger tributary streams flowing into the Grand Canyon. Bright Angel Creek begins in earnest at Roaring Springs around 10 miles upstream. The water bursts out of the rock at the base of the Muav Limestone as an instant river. There is so much water that pumping stations were built so that the springs supply the water needs of the developments at both the North Rim and South Rim of Grand Canyon National Park: all the hotels, the campgrounds, the visitor centers, and the restrooms. And there is enough left over that the creek flows all year at the Ranch and supports a robust population of fish (eight native species originally and two introduced trout species that are being removed).
We moved on downstream. It was a short day on the river, only five miles total, so we drifted with the current for awhile, passing gigantic towers of schist and granite. The peak in the picture below reminded me of Sentinel Rock in Yosemite Valley.
As we noted in yesterday's post, these rocks are the deep crust remnants of a 1.7 billion year old mountain range that once extended from at least California (Death Valley area) to Mexico and perhaps Oklahoma and Arkansas. The mountains were pushed up as a result of the collisions between a series of island terranes and the core of the North American continent.
These rocks used to be mud and silt on the ocean floor, or volcanic rock like one sees in Japan or the Aleutian Islands. The rocks were crushed, buried, and heated nearly to the melting point, but not quite (different minerals melt at different temperatures, so part of the rock could have been molten, but not all of it). The rocks were twisted and folded like saltwater taffy, and later on they were intruded by hot masses of granitic magma, forming the pink rock in these pictures.
I was walking in a small unnamed canyon just upstream of Salt Creek (our camp was very creatively called "Above Salt Creek"). There was a small trickle of water.
The little bit of erosion has attacked the boundary between the schist and the granite, highlighting a fold in the schist.
My ankles were bothering me again, so there was no way I was going try to climb the jumble of boulders at the head of the canyon, but before I got there my attention was drawn to one of the strangest rocks I had seen in awhile. It was bright red.
Most of the time, geologists are pretty loose with their definition of the color red, using it to describe a lot of brown and reddish brown rocks and sediments. But this stuff was really red. It was essentially fine-grained, but may have had small phenocrysts (small crystals) of a white mineral, maybe feldspar. I couldn't tell, and to my shame I was caught in the wild without my handlens! It was fairly easy to weather, as you can see from the mineral veins that stand out in relief (this is material, probably calcium carbonate, that filled cracks and fissures in the rock much later).
I'm guessing it might have been some kind of metavolcanic rock, but really as a non-petrologist, I am not at all sure. Any ideas out there, gang?
The shadows grew longer in the dark canyon as the boatmen checked their rigs. Tomorrow was promising to be the most challenging day of the trip, with at least ten major rapids, including Granite (8), Hermit (8), and Crystal (9-10).