Talk:Geology of the Grand Canyon area

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Old talk[edit]

Hi Mav, re the centre/right thing, I disagree, but not enough to want to argue about it - if we are going to center it, why don't we go the whole way and make it as wide as we can? I know, I know, but the Grand Canyon is perhaps the only page that would really justify this kind of treatment! Mark Richards 20:12, 28 Apr 2004 (UTC)

We are limited by what people with 800x600 screens can see. --mav

I removed this from the Grand Canyon page - I think its all covered here. Wow - there is SO much work to do on this still! Let's go! Mark Richards 19:34, 28 Apr 2004 (UTC)

The strata, from the bottom to top, are:

   * Early Proterozoic Schist and Granite: 1.7 billion years ago
         o Vishnu Schist 
   * The Earlier Unconformity: 1.7 to 1.25 billion years ago
   * The Middle and Late Proterozoic Grand Canyon Supergroup: 1250 to 820 million years ago
         o The Uncar Group
         o Bass Limestone
         o Hotauta Conglomerate
         o Hakatai Shale
         o Shinumo Quartzite
         o Dox Sandstone
         o Cardena Lavas 
   * Nakoweap Formation: 1 billion years ago
   * The Chuar Group: 950 million years ago
   * The Sixtymile Formation: 820 million years ago
   * The Great Unconformity: 820 to 570 million years ago
   * Paleozoic Sediments: 570 to 245 million years ago
   * The Cambrian Tonto Group: 570 to 505 million years ago
   * A Pre-Devonian Unconformity: 505 to 360 million years ago
   * Devonian Deposits: 408 to 360 million years ago
         o Devonian River Channels
         o Temple Butte Formation 
   * The Redwall Limestone: 360 to 320 million years ago
         o Surprise Canyon Formation 
   * The Supai Group: 320 to 286 million years ago
         o Watahomigi
         o Manakacha
         o Wescogame
         o Esplanade 
   * The Hermit Shale: 286 to 245 million years ago
   * Coconino Sandstone
   * The Toroweap Formation
   * The Kaibab Formation
   * Mesozoic Geology: 245 to 66 million years ago
         o Shinarump Conglomerate
         o Moenkopi Formation
         o Chinle Shale
         o Chinle Formation
         o Moenave Formation
         o Kayenta Formation
         o Navajo Sandstone
         o Caramel Sandstones
         o Entrada Sandstones
         o San Rafael Group
         o Dakota Sandstone
Yep - still a lot to do. --mav

Invisible references[edit]

Invisible references via the Inote template (see talk page) are now implemented in this article. Your comments appreciated. Mozzerati 21:44, 2005 Apr 20 (UTC)

Should there be any talk about the current controvery over the grand canyon's age?[edit]

These articles suggest that there may be some controversy in the government's stance on the geological age of the grand canyon.

[1] [2] —The preceding unsigned comment was added by Chrisdab (talkcontribs) 22:23, 6 January 2007 (UTC).

See the discussion at Talk:Grand_Canyon. The fact that the government may choose to ignore science does not mean that the age of the Grand Canyon is controversial. Geologyguy 22:37, 6 January 2007 (UTC)
There is more then one theory on how the Grand Canyon formed. And this also includes differences in the age of the Grand Canyon. If someone has literature, please show it here. --41.18.46.57 (talk) 07:39, 11 July 2009 (UTC)
If you have a reliable source about any other geological estimates of the age of the canyon, please mention it. But I'm pretty sure that the ice age is the only valid theory for it's formation. Auntie E (talk) 13:08, 11 July 2009 (UTC)
Canyon formation likely went faster during the ice age due to increased precipitation but I would not say that it caused the canyon's formation. Rather, downcutting of the Colorado River as the Colorado Plateau rose and the Gulf of California opened up is the consensus view. --mav (talk) 02:23, 31 August 2009 (UTC)
A tempest in a young-Earther crackpot does not a scientific controversy make. --mav (talk) 02:23, 31 August 2009 (UTC)

There is certainly scientific uncertainty over the exact age of the Grand Canyon as evidenced by the ongoing research. The NPS Grand Canyon website contains lots of scientifically valid information and I could find no hint of a younger age for the canyon. The statement is made on the website that the canyon is 5-6 million years old and shows new and older rock formations with ages of a few hundred million to billions of years old. I was just at the canyon a few weeks ago. I guess I should have polled the employees for an age estimate :). Desoto10 (talk) 01:04, 17 September 2009 (UTC)

From what I've read, it is much more an issue of definitions; Did something we know as the "Grand Canyon" exist prior to 5 to 6 million years ago? Well, it depends on whether or not you call one or the other of the (at least) two ancestral canyons that eventually merged, the "Grand Canyon" or not. IMO, the Grand Canyon did not exist until the merger and we have a ballpark figure for when that happened. Unfortunately, much of the downcutting prior to 5 to 6 million years ago occurred in Mesozoic-aged strata that have since been almost completely removed from the Grand Canyon area. Much was also carried away by expansion of the canyon itself. Pitty. I would love to know where the upper canyon emptied and exactly how the merger happened. --mav (talk) 13:02, 20 September 2009 (UTC)

Why name it 'Vishnu Schist'?[edit]

What about the history of the names given to various layers? Especially, the 'Vishnu Schist', whats the origin of this name? 'JB, 15-May-2007, Australia'

Most geological formation names are based on some local geographic feature in the area where the rock unit was described. I know there is a Vishnu's Temple in the Grand Canyon, and maybe other similarly named locations. Many of the geographic features, including many with names from Hindu theology such as Vishnu, Shiva, and Krishna, were given by USGS explorer Clarence Dutton in 1880-81. Hope this helps. Cheers Geologyguy 02:11, 15 May 2007 (UTC)
Also, Zoroaster, as in the Zoroaster Granite, is a prophet from the religion Zoroastrianism.
In almost all cases, that info is more appropriate in articles about the individual formations. --mav (talk) 02:24, 31 August 2009 (UTC)

Photo not of a crinoid?[edit]

In the section "Hermit, Coconino, Toroweap, and Kaibab", there is a photograph with the caption "Fossils, such as this one of a crinoid, are common in the Toroweap and Kaibab formations". The predominant feature in the photo looks like the pedicle valve of a Productid brachiopod. Although there might be some crinozoid stems in the photo, I think the caption should be changed to "Fossils, such as this one of a brachiopod...". Or am I just missing something? —Preceding unsigned comment added by Sonomadiver@gmail.com (talkcontribs) 21:39, 6 July 2010 (UTC)

You're not missing anything, the original source of the photo confirms that the large fossil is a brachiopod. I'll modify the caption accordingly. Thanks for spotting that. Mikenorton (talk) 22:17, 6 July 2010 (UTC)
Thanks for the feedback! - sonomadiver

Galeros Formation[edit]

From the article "Galeros Formation is a mainly greenish formation composed of interbedded sandstone, limestone, and shale with some shale. It ranges in color from red to purple".

  • "Shale with some shale" looks like an error.
  • What is the color of Galeros Formation?

Avihu (talk) 06:21, 1 September 2012 (UTC)

Fixed some wording, the redundant "some shale" bit and took out the "red to purple". The colors and lithology of the formation are variable, don't have the ref used -- but for the brief summary given that may work. Details of the group are available in: Ford, T.D. and Breed, W.J., 1973, Late Precambrian Chuar Group, Grand Canyon, Arizona: Geological Society of America Bulletin, v. 84, no. 4, p. 1243-1260. Vsmith (talk) 13:54, 1 September 2012 (UTC)

Toroweap Formation[edit]

Toroweap Formation is "is a ledge- and cliff-former" and is divided into the following three members: Seligman is a slope-forming, Brady Canyon is a cliff-forming and Wood Ranch is a slope-forming. Two out of three are slope-forming, but the formation as a whole is a ledge- and cliff-former? Avihu (talk) 18:22, 8 September 2012 (UTC)

Changed per Toroweap Formation and strat column (fig 1). Vsmith (talk) 00:13, 9 September 2012 (UTC)

Volcanic activity dams the new canyon[edit]

From the article "Dams that were 150 to 400 feet (46 to 120 m) high were overtopped by their lakes in 2 to 17 days while dams 200 to 1,000 feet (61 to 300 m) high were overtopped in 22 years. 400 feet dams in just up to 17 days, but 200 feet dams in 22 years? Avihu (talk) 17:44, 14 September 2012 (UTC)

That does seem off a bit ... don't have the book (Beus, Stanely S.; Morales, Michael, eds. (2003). Grand Canyon Geology (2nd ed.). New York, Oxford: Oxford University Press. ISBN 0-19-512299-2) used as a reference to check. Looks like that was added by User:Mav at 03:40, 14 September 2009. I'll ask him to stretch his memory back 3 years or maybe check the source and add / fix for clarification. Vsmith (talk) 00:55, 15 September 2012 (UTC)
Yep - Page 321 does say "22 years" but now that I think about it, it must be an error in the book since the sentence right before that says that overtopping was very rapid. 22 "days" makes much more sense in that regard. Absent another source confirming that, our only recourse is to comment out that part. I'll do that. --mav (reviews needed) 13:54, 15 September 2012 (UTC)
Well, I found source that corroborate the 22 years period. See the description of Prospect Dam on pages 34 and 35 of Jeremy Schmidt, The Grand Canyon National Park: A Natural History Guide. Avihu (talk) 17:36, 22 February 2013 (UTC)

The Bass Limestone[edit]

From the article "The Bass Limestone was deposited in a shallow sea near the coast as a mix of limestone, sandstone, and shale. It is 120 to 340 feet (37 to 100 m) thick and grayish in color." According the USGS site it contains dolomite and not limestone (contrary to the formation name), it's color is "Red-brown and reddish-gray" and it is "260 to 300 ft" thick. The color and the thickness are just small variations from what is written in the article, but the lithology is not. By the way the elaborate Rock Hounds site also specify dolomite instead of limestone. Avihu (talk) 17:34, 17 September 2012 (UTC)

Vsmith? Mav? Anyone? Avihu (talk) 16:48, 19 September 2012 (UTC)
The Harris ref (through Google books p 21) does state that and is in disagreement with the USGS website. Harris has only a brief mention of the Bass - essentially what is in the article and no more. The USGS site switches to Bass Formation and gives a bit more detail, including the dolomite part. I suppose it could be read as the Bass was deposited as a limestone which was later dolomitized... but that's reading more than the refs explicitly state. I'd say, go with the more detailed USGS ref. Vsmith (talk) 00:51, 20 September 2012 (UTC)
That's what I did in my translation of the article into Hebrew. In the Hebrew Wikipedia we have a rule that you can use source only if you read it yourself. Unfortunately almost all the books in the reference section of the English article are unavailable through Google books, so I had no choice but to search for replacements and this how I got to find this discrepancy between the Article and the USGS site. I leave it to you guys to update the English version. Avihu (talk) 17:25, 20 September 2012 (UTC)

Vishnu Schist[edit]

From the article "when thousands of feet of volcanic ash, mud, sand, and silt were laid down in a shallow backarc basin similar to the modern Sea of Japan", this need a bit of clarification. Avihu (talk) 17:08, 30 September 2012 (UTC)

?? Avihu (talk) 15:00, 2 October 2012 (UTC)
???? Avihu (talk) 19:53, 28 October 2012 (UTC)

The first two paragraphs became a bit confused with lots of edits and use of different refs. Some edits made in an attempt to clear that up a bit. Please take a look. --mav (reviews needed) 22:17, 28 October 2012 (UTC)

I am not sure that deleting the reference to "thousands of feet" is doing justice to the article. In the article GEOLOGY OF GRAND CANYON NATIONAL PARK, NORTH RIM, Annabelle Foos from the Geology Department, University of Akron is very specific "The oldest rocks exposed in the Grand Canyon are the Proterozoic Vishnu schist. Approximately 2 billion years ago, 25,000 feet of sediments and volcanic material were deposited on the sea floor". Avihu (talk) 05:03, 29 October 2012 (UTC)

quote from Beus and Morales[edit]

Supai Group[edit]

In this section, a part reads, "thickness of 600 to 700 feet (200 to 200 m)." The metric part needs to be looked up from the original source and updated (I could use conversions to write "(183 to 213 m)", but that doesn't seem like a good change). — Preceding unsigned comment added by 24.94.232.216 (talk) 05:42, 11 November 2012 (UTC)

The metric part is an automated conversion showing only one significant digit. Normally that is correct given the likely ambiguity in the cited data ("600 to 700 feet"), but a difference of only 100 feet rounds to 200 meters for both cited values in the range when only one sig fig is used. So I got rid of the convert template and just give (around 200 m) for the metric conversion. --mav (reviews needed) 14:10, 11 November 2012 (UTC)