Friday, May 29, 2015

Grand Canyon Field Institute 10-Day Colorado River Rafting Trip - Part 2 Phantom Ranch to Diamond Creek

Part 2 of this 10-day Grand Canyon raft adventure begins downstream from Phantom Ranch.

The angular unconformity between the Grand Canyon Supergroup (lower tilted strata) and the Cambrian-age Tapeats Sandstone. Note that the Supergroup rocks are beveled to near horizontal suggesting a long period of erosion to plane them flat.

Wider view of the same unconformity, exposed near Stone Creek in Grand Canyon (river mile 132). The lighter colored Supergroup rocks belong to the Bass Limestone and are underlain by darker intrusive rocks that invaded the limestone about 1.1 billion years ago.

Downstream view along the Colorado River from Stone Creek camp showing the same limestone-over-intrusive rock as the previous photograph.

Group photo at Stone Creek Falls. We were able to lay over here for two nights and thus hike up into Stone Creek.

Grand Canyon is home to hundreds of springs that populate the floor of the canyon with lush riparian vegetation. Stone Creek is one of the warmer falls, especially in the summer.

A chuckwalla basks in the morning sun in Stone Creek Canyon. These vegetarians are among the largest lizards in Grand Canyon and defend themselves by wedging into cracks in the rocks and then puffing up their stomachs with air.

Cactus field in Stone Creek Canyon

A flood in Stone Creek about six years ago exposed a cross-section through an ancestral mescal pit (agave roasting pit). This pit is lined with red rock slabs near its base (bottom center) and appears to be still filled with the once heated rocks. Why this pit is still rock filled is a mystery - was the agave cooked but then never gathered?

The canyon tree frog is found in most Grand Canyon streams and makes a rather vocal call for such a small amphibian.

Another waterfall along Stone Creek's upper reaches

And yet another fall, this one at the head of our day's exploration. Many springs are located on the north side of the Colorado River and beneath the North Rim, where snowfall amounts in normal years can reach upwards of 200 to 250 inches. About 10% of this snow will make its way into the aquifer to supply the springs

Water in the desert is a true miracle and the Grand Canyon is full of miracles!

Arriving back at camp on the Colorado River. We were  very fortunate to have this camp for two nights on this trip.

Prickly pear cactus frames Deer Creek Falls along the Colorado River. These falls are relatively "new" as the old alignment of Deer Creek was blocked by a giant landslide. Now Deer Creek is in the process of excavating a new canyon to the river.

Note the Great Unconformity near the top of the Falls where the Tapeats Sandstone overlies the Precambrian granite. This gap in the rock record is about 1.2 billion years of duration.

Evidence for the giant slide that blocked the former path of Deer Creek and the Colorado River can be seen from the landing at Deer Creek Falls. Note the yellowish-colored rubble sitting atop the layered Tapeats Sandstone. This is the rusty brown dolomite of the Bright Angel Shale that has traveled along a giant mega-landslide from the north side of the river (right). This material slipped on weak Bright Angel Shale and slumped downwards into the canyon of the Colorado River, blocking it and creating a dam. The rusty brown material shown here actually rides even higher up the slope (out of view here) to a point above where it it is still in place on the south side!

After visiting Havasu Canyon, we camped on some ledges within the Muav Limestone

At first, the group was skeptical about camping directly on solid rock

But with thick and comfortable sleeping pads, ledge camping has become kind of a desired option on these trips. The proximity to the river in a narrow place provides scenic opportunities like no other.

The Icebox section the river lived up to its name on this early May trip. But the entire west experienced abnormally cool and moist conditions during the month. We were lucky to have been in one of the warmest places around during this time.

The far western Grand Canyon is quite different than the more frequently visited areas to the east. Here Mojave Desert vegetation dominates, the early Paleozoic rocks become more marine and limey, and the whole character of the canyon changes. This sand bar has formed on an island in the river near Granite Park (river mile 209).

Scene from a Colorado River cobble bar in western Grand Canyon.

It was wonderful to see and feel the warmth of the sun this afternoon

Giant barrel cactus in western Grand Canyon

I've barely said a word about the folks on this trip who were such a pleasure to travel with! Here Larry C. entertains Mickey H. with his four-string ukulele. We had so much fun in these camps for the ten days.

Our lead guide Jack, cooks up some nice steaks at Granite Park camp

And our assistant guide Kim, whose smile was graciously infectious and welcomed! AzRA gave us a fantastic trip down the river.

Sunrise on the basalt lava flow remnants near Granite Park

Wider view of the lava flow remnant on top of the Tapeats Sandstone. The moon is barely visible in this size photo in the background.

The strata in western Grand Canyon is confusing to most people because there is a thick stack of limestone that is difficult to differentiate. I provide a guide to it below.

Annotated guide to western Grand Canyon limestones. I have not labeled the unclassified dolomite that is found between the Temple Butte and Muav limestones.

Beginning of the Lower Granite Gorge. Grand Canyon has three of them - Upper, Middle and Lower.

View of Diamond Peak (right) and the trace of the Hurricane fault (center valley). Diamond Peak is capped by Redwall Limestone. The fault places Vishnu Schist (darker crags on the left) against the Muav Limestone ledges to the right, showing a throw on the fault of about 1,500 to 2,000 feet.

Final view of the Lower Gorge before the Diamond Creek take-out. Thanks to everyone who participated in this adventure and for supporting the Grand Canyon Field Institute!

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