Sunday, July 24, 2016

A Smoke-Filled Grand Canyon Rafting Trip

If it seems like I am doing a lot of Grand Canyon river trips this year, let me say that I will be doing five of them this year; one each in May, June, July, August and September. There is a nice symmetry to a schedule like that. I get to see the canyon emerge from winter into its flower-dappled spring and slowly roll into the dog days of summer, with just a hint of Indian Summer at the end. I like that. I recently finished my third trip and was worried from the start that this might be the hardest with the heat dome that has developed over North America this year. But we saw some monsoon clouds and moisture, and there was a wonderful group of 11 people. This was one of my geology-charter trips.

Bright, clear sunshine at the start as we float through the Supai Group of rocks. Note the haze in the far distance - that is smoke from the Fuller Canyon Fire on the North Rim.

Vasey's Paradise is normally a good size spring issuing from the Redwall Limestone but its discharge is much compromised this season with the relatively low snow pack on the North Rim this past winter. The large hole on the left is completely dry and just a trickle comes out at center.

Just past Redwall Cavern, we entered the smoke zone. It was eery and weird looking to see the canyon in an orange haze.

It reminded me of my high school days in southern California when we ran track and field in the height of the smog epidemic.

This was the day that the fire grew from about 3,000 to 14,000 acres due to a flare up in the wind. We were right below the fire up near Saddle Canyon.

It did make for some pretty interesting pictures.

I'm not sure what everyone made of the smoke although a few were bothered by it at night. We did do the Saddle Canyon hike in the smoke as it drifted in and out of the canyon above us.

We finally got beyond the smoke and could look back upstream as it billowed up over Saddle Mountain.

With the smoke gone, we decided to hike to the Nankoweap granaries. I never would have imagined doing this on a middle-of-July trip but we started early and hiked with wet clothing. It was a breeze!

And a great view!

These are the granaries, located in a niche cut into the Muav Limestone about 800 feet above the Colorado River. They likely were constructed about 1,000 years ago by farmers who lived near the delta of Nankoweap Creek.These granaries were used to keep critters from getting into food stores at night, just as on river trips today when food and trash is put in closed containers to prevent the same.

A final view of the Colorado River from the granaries.

We set up lunch in some rocky ledges etched into the Tapeats Sandstone just below Sixty-Mile Rapid. Many people wonder how the ledges form, if the whole deposit is sandstone? The question actually is:"If it is all sandstone, why does it erode in such nice neat layers?"

The answer can be found looking back under the ledges. The formation is not entirely sandstone but actually interfingers with stringers of Bright Angel Shale. Notice how the shale is more readily excavated by the river since it is softer. The sandstone becomes undercut and ultimately collapses downward.

This is the Sandra, an original 1940's-era cataract boat made by Norman Nevills, considered by most to be the first commercial outfitter in Grand Canyon. Rowing the boat is Greg Reiff, the grandson of Norm Nevills. He patched her up and has now made 33 trips in the Grand Canyon with her.

Travertine 'drapes' on top of the Bright Angel Shale. The travertine formed when spring water, saturated by the dissolution of calcium from the Redwall Limestone, degassed and precipitated limestone. To a geologist, travertine is spring deposited limestone, to counter-top makers travertine is everything from limestone to marble to who knows what. The dates on this travertine are around 330,000 years.

The same process continues nearby within the drainage of the Little Colorado River. About 13 miles upstream from the confluence of the two rivers, is Blue Springs, the largest spring in Arizona at about 220 cfs. Groundwater is dissolving calcium in the Redwall Limestone (where the spring issues from) and the dissolved calcium gives the water its blue color. As the water runs over boulders, the CO2 is driven off and travertine forms in the bed of the LCR.

Wow! The canyon would be spectacular enough but then this warm, colorful water frames it all.

At home in a rocky paradise.

Running Unkar Rapid with the Dox Sandstone above the rapid.

One of the more popular camps above the Inner Gorge is Upper Rattlesnake Camp. I've camped here a lot and have grown quite fond of this little outcrop in the Dox. It is a mudstone/shale that is bounded above and below by thin layers of sandstone. It's like an ice cream sandwich. But the mudstone appears as if it is two weeks old! You could find materials like this on any exposed river floodplain. That is how unchanged it is after over 1 billion years.

Our boatman, Mikenna, has "adopted" the Clear Creek beach. You can read about the Adopt a Beach Program of the Grand Canyon River Guides here. As we stopped, I noticed the fabric in the Vishnu Schist and took a few pictures.

Erosive patterns composed of gray schist rock (metamorphosed shale or sandstone) with light colored quartz dikes (once molten magma).

Interesting shape with quartz dike remnants still plastered on in two places.

I like to set up my bed near the beach where it is a bit cooler in the summer for sleeping.

On our way to Elves Chasm in the Tapeats Sandstone.

Two large boulders of travertine frame the beautiful waterfall.

The Desert Spiny lizard (Scleroperos magister). They can change their color to better absorb or reflect heat.

Spectacular setting on top of Deer Creek Falls after a good hike of about 300 feet uphill. That's the Powell Plateau in the far distance. Note also how the Tapeats Sandstone across the river pinches out gradually away from the photographer. This was the location of a substantial knob of granite that protruded above the Tapeats depositional plane.

Looking into the Deer Creek Narrows from the trail above.

Wild plant garden.

Here is everyone from the trip, except myself who took the picture. You all were great river companions!

3 comments:

citizenschallenge said...

Looks like a great time, despite the fires.
One of these years I'm gonna be on one of those trips.
Wayne, me know if your ever looking for a cook, dishwasher. ; - )


Happy Trails.

Deb Larsen said...

Appreciating the oddities we see... The old rock that resembles the ice cream sandwich. Keep sharing the fun stuff too. Like how your brain works, Wayne.

BELINDA BILLS said...

Another great trip Wayne!