Tuesday, December 28, 2010

2008 Day 2 Mile 26.2 to Saddle Canyon Camp 47.2

Day 2 Mile 26.2 to Saddle Canyon Camp 47.2

Wayne discussed the five criteria needed to form the Grand Canyon in the morning talk (I have a 25 minute recording of the whole talk for Day 2 - available by request is a 25MB mp3 of the recording - later with Wayne permission I may provide access to the over 1GB avi video):
1.    Large expanse of stratified rock
2.    Variably coloured (pretty/brightly coloured also in our case)
3.    Gently uplifted
4.    Eroded/Exposed by Big River(s)
5.    Dry Arid Environment
Wayne also showed maps/images of what the southwest US looked like when the various layers of the grand canyon were deposited (at sea level).  These are featured in Wayne's Ancient Landscapes book (which become available soon after the 2008 trip).

05:35 wake up early, pack - eager to continue the river trip

06:45 The chair circle gets good use as we eat breakfast - below Wayne talks to Mike Miller

River level is beginning to be dominated by Red Wall Limestone - we REALLY are in a "grand" canyon now photo taken 08:47

08:49 Mile 28 Redwall Limestone is permeable to water and sensitive to being dissolved by even slightly acidic ground water/rain.  It has many caves and features formed by water/solution deposits.  See the caves and water formed surface features below.

Later when the Muav appears we will find that a spring at that level saturates the Muav before it can extend up into the Redwall and that water sources feeding the Redwall often flow downward into the Muav.   Here is an article on geology impact on water along the south rim discussing springs, recharge and flow patterns. 

The Grand Canyon is widened by side channel erosion - here is a pour off in the Redwall (over time a side canyon will form).  Wayne pointed out that anytime you see a waterfall near the river, this is relatively new and temporary - headward erosion will move this back forming a side canyon.

Mile 31.7 we see Stanton's Cave in the Redwall (this has hundreds of feet of passages formed by water/roof rockfall combined with water - notice the debris below the entrance)

Processing the image to enhance dark detail we can see the "bat gate" used to prevent human interference while allowing the bats access to their cave

Much of the Grand Canyon area is desert but springs and side canyon water sources create riparian environments with plant and animal diversity.
Vasey's Paradise at mile 31.9 is an example of north rim groundwater coming out of the Redwall (springs out of limestone are fairly common in the Grand Canyon)
See all the small openings formed by water dissolving limestone

Mile 33.1 the Redwall Cavern appears in the distance

At first it appears "small", but size can be deceiving - see the people (this is a BIG cavern)

10:15 We continue to see a number of springs out of the limestone - at roughly mile 34 here is a nice example
Mile 34.8 we hike up Nautiloid Canyon (cut into Redwall Limestone approx 350 million years old or early Mississippian)

There are many fossils of Nautiloids (cephalopod mollusks) - this one was about a half meter long.

Mile 35.8 we see the Bridge of Sighs - an arch in the Redwall (notice the caves to the left of the arch, guess how the arch was formed)

Mile 36 we see the Muav Limestone appear for the first time

Wayne lectures on the geology appearing around each bend - above him in the below is the Eminence Break mega-landslide (a favorite hike of mine done in both 2009 and 2010)
Mile 38 onward we see "Smiley Faces" formed of Temple Butte Limestone.  In the eastern GC this formed in river channels so is sparse but as we move west the deposits become more frequent and finally join up into an expanse of Temple Butte Limestone up to 400 feet thick within the Grand Canyon and over 1000 feet thick further west.  Temple Butte Limestone looks much like the Redwall but is found between the Redwall Limestone and the Muav.

Mile 39.2 we see an adit cut into the Muav Limestone.  This several hundred foot long test hole is part of the Marble Canyon Dam site.  It is connected to a drift in the Redwall Limestone above it (2nd photo) - we are grateful this dam was never built as we (and a key part of the Grand Canyon) would be deep under water.

Detail of Redwall drift - note remains of steel
Mile 43 we see the Anasazi Bridge made of wood spanning a gap in the Muav Limestone (no way do I see how one got up to that bridge!).

Our campsite at mile 47.2 was Saddle Camp - a hike up Saddle Canyon was done before dinner and covered by Sueanne in detail.  See the Temple Butte Smiley Face from Saddle Canyon (above Ed in the below photo).

Below is a 2004 trip photo with more detail of the identical area (source is http://www.physci.mc.maricopa.edu/Geology/FieldTrips/ColoradoRiver/2004Summer/ColoradoRiver_su04_Images_Day03.htm)

Saddle Camp had great views of Redwall cliffs - note how much deeper into the canyon we are at end of day 2.

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