The Muav Limestone This unit, the Muav Limestone, and the two preceding units (the Tapeats and the Bright Angel) together are known as the Tonto Group. All 3 of them were deposited in the Cambrian and together they represent a fairly traditional sequence of rocks. When sea levels rise substantially, the rocks often record a sequence of shallow-water sandstones followed by quiet water shales and marine limestones formed when the water levels peaked. That story is told quite well in the Tonto Group. The Muav is a yellowish-gray limestone that forms slopes in-between the easily eroded Bright Angel formation and the thick limestones above. It contains some fossils but they’re few and far between. The rock is a mostly fine-grained limestone known as a micritic limestone. The rock actually tells a good amount about the sedimentary environment in the Canyon area. In the eastern part of the Canyon, the unit is thicker and the limestones are interbedded with siltstones reminiscent of the Bright Angel formation. In the western part of the Canyon, the unit is nearly twice as thick and is a much more pure carbonate. The silt supply came from higher ground in the East and didn’t make it to the west. The rocks were deeper in the west, leaving more space to accommodate sediment. -JBB Image credits: https://flickr/photos/grand_canyon_nps/7705972158/ https://flickr/photos/grand_canyon_nps/6094535727 Read more: 3dparks.wr.usgs.gov/coloradoplateau/lexicon/muav.htm bobspixels/kaibab.org/geology/gc_layer.htm grandcanyonnaturalhistory/pages_nature/geology/7-muav.html asset.emsofl/ONLINE%20CLASS/EarthSci/_labdata/unit7/pages/strata/muavlime.html Previous articles: https://facebook/photo.php?fbid=71718732167564 https://facebook/photo.php?fbid=717596974968016 https://facebook/photo.php?fbid=718487278212319 https://facebook/TheEarthStory/posts/718917208169326 https://facebook/TheEarthStory/posts/719035941490786 https://facebook/TheEarthStory/posts/719534524774261 https://facebook/photo.php?fbid=720485404679173 https://facebook/photo.php?fbid=720916891302691 https://facebook/TheEarthStory/posts/721282287932818 https://facebook/TheEarthStory/posts/721455997915447 https://facebook/TheEarthStory/posts/722212221173158 https://facebook/TheEarthStory/posts/722332104494503 https://facebook/TheEarthStory/posts/723288294398884 https://facebook/TheEarthStory/photos/a.352867368107647.80532.352857924775258/723925267668520/?type=1 https://facebook/TheEarthStory/photos/a.352867368107647.80532.352857924775258/724756080918772/?type=1 https://facebook/TheEarthStory/posts/724792024248511 https://facebook/TheEarthStory/posts/725410850853295 https://facebook/TheEarthStory/posts/726153457445701 https://facebook/TheEarthStory/posts/726938514033862 Dear Readers, Most of our posts are not reaching you in your news feed due to fbs filtering system. If you wish to enjoy our posts more often, use the following for information on how to go about it: tinyurl/qgwac8k.
Posted on: Wed, 30 Jul 2014 21:25:01 +0000