Saturday, January 1, 2011

2009 Day 5 Sep 17 Grapevine 81.5 to Big Dune 118.7

Sept 2009 Geology River Trip - Day 5 Part 1 Grapevine to lunch stop (Sept 17 from Grapevine 81.5 to Big Dune 118.7)

This journal covers Day 5 – from Grapevine Camp to Big Dune.

06:57 Wayne Geology lecture – inner gorge behind him (which was a key topic).


08:10 Polished inner gorge gleams in the morning sun


08:23 The inner gorge climbs above us


08:24 until the Tapeats stands high above our course


We pass Clear Creek pull-in (one has to climb over the fins seen here to enter the creek which is a walkup)


Clear Creek entry – pleasant hike up to a dry fall – we did not stop this trip as we had distance to travel


08:35 inner gorge is NOT a barrier for Bighorn - we see today’s first bighorn pair – we would see many today


Around 08:50 we pass the gauging station


And stop at the boat beach to get water and let folks go check out the flesh pots of Phantom Ranch


09:24 I personally ran to Phantom Ranch for the tee shirts (new styles every year – you just gotta get them all)


And the famous lemonade


We get the water and quickly get back on the river

10:39 Bighorn female on beach


11:17 Raven says “This is a great beach, please stop”


So we do – for a quick lunch break and a few use the opportunity for side hikes – 11:23 here Wane heads up a side canyon to check out the geology


11:37 here is a nice colorful agate in conglomerate we see on the beach


11:39 and a polished limestone boulder


End of part 1 of Day 5 – continued in Part 2

Subject:  Sept 2009 Geology River Trip - Day 5 Part 2 lunch stop to Big Dune (Sept 17 from Grapevine 81.5 to Big Dune 118.5)

This journal covers Day 5 – from Grapevine Camp to Big Dune.  Part 2 – from lunch stop to Big Dune Camp at mile 119

12:28 after lunch we head down river – here is a schist vein in granite that looks like it spells out NY or perhaps even I heart NY (OK, only to a New Yorker)


13:06 Amphibolite embedded in gorge wall near the river


13:21 More bighorn – first a female spots us


13:21 and there is the bighorn male


13:30 around mile 107 ahead we spot Powell Plateau – notice the lone pine that stands out on the right – Wayne hiked there for his birthday


13:30 Here is a telephoto shot of that tree


Mile 107.5 shortly before the Ross Wheeler we see Dox Castle ahead on river right (right skyline) – notice other Supergroup  below and middle skyline.

Dox Castle is the type locality for Dox Formation and was named by William Bass after Virginia Dox (the first female visitor he guided in the grand canyon).

Link to another photo from the esplanade of Dox Castle on the web.


13:40 in this area we were temporarily lost (at least based on Drew’s expression)


13:49 but soon spot the Ross Wheeler around river mile 108 (river left) which we can place on the map and thus get unlost


Here is a detail zoom of the metal boat (which is chained to rocks above the high water line to prevent river high jinks from “messing with it”)


Mile 108.x supergroup is again visible for the next few miles due to faulting - In this area we see Hotauta Conglomerate, Bass Limestone, Hakatai Shale, Shinumo Quartzite, and Dox Formation


13:52 shortly after we spot the Bass mine tram ruin on river left (around mile 109)


13:59 we pass an AZRA trip that had Ed Hasse from the 2008 geology trip as crew


14:02 Mile 109 View northwest towards the Redwall-capped Fan Island (on middle skyline). The Tapeats ends abruptly against a Shinumo island below and right of Fan Island.

Wayne discussed this area, the return of the supergroup, and the Shinumo island at some length on the river.



14:05 Mile 110 Rapid


In the photo below the inner gorge rock at the lower right is the dark Elves Chasm Granodiorite/Gneiss is the oldest dated rock in Arizona (at 1840 Ma) and represents a metamorphosed granodiorite pluton even older than the oceanic sediments and lavas of the Vishnu, Brahma, and Rama units. It is thought to be similar in age and composition to the Trinity Gneiss. Note the light-colored dikes of the Garnet Pegmatite Suite.  Here is a link discussing metamorphic facies showing the relationship of temperature and pressure (and therefore depth) to which metamorphic rocks were formed.  Wayne discussed how depth and temperature determined the characteristics of the inner gorge rocks we have been seeing today.


Mile 115 Light colored dikes intrude Elves Chasm Pluton (nicely exposed at river level)


14:50 Mile 115.9 we observe a fault in the Tapeats (notice the Tapeats is not impacted left or right of the fault)

This fault is named the Monument Fold – it dates from the Laramide Orogeny and is about the same age as the Butte fault.

First photo is river right where the displacement is less pronounced.


Here is the fault on river left where it is much more obvious


A close-up of the fault


15:09 As quickly as the inner gorge rose, it now starts to descend . . .


15:09 we were passed by many birds in this section – here are three (sorry for the focus problems in this image – if someone has a better shot it would be VERY welcome)


15:16 just a few minutes later we have the Tapeats at the river’s edge – this was a beautiful day in the Grand Canyon


15:41 we soon stopped at Big Dune – here Mark and Cindy setup camp


15:58 getting to camp early allowed us to do some fun climbing in the Tapeats ledges


16:02 nice views up and down river


And a photo of the view from just before our turnaround up on the ledges


16:57 the obligatory groover photo in Big Dune Camp


16:58 view of the camp – this was a great campsite!


17:06 there are four Sacred Datura (moon flower) buds in the below that will open tonight (these are yellow and standing up – flowers from prior nights are white and fallen down)


Moonflower Blossom


17:08 the point below our camp (where we hiked to)


End of part 2 of Day 5 – end of Day 5

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