# Raven Ridge

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{{Short description|Sedimentary rock exposure in Colorado and Utah, U.S.}}
{{for multi|AMD's APU codename|AMD Raven Ridge|the place in Washington state|Raven Ridge (Washington)}}

[[File:Raven Ridge, Colorado.jpg|thumb|upright=1.4| Raven Ridge. NASA satellite photo, 2008.<ref name="nasa">[http://earthobservatory.nasa.gov/IOTD/view.php?id=36504 Raven Ridge, Colorado] at NASA Earth Observatory</ref>]] 
'''Raven Ridge''' is a starkly visible [sedimentary rock](/source/sedimentary_rock) exposure located in [Rio Blanco County](/source/Rio_Blanco_County), [Colorado](/source/Colorado) and [Uintah County](/source/Uintah_County), [Utah](/source/Utah), USA.  It is managed by the [Bureau of Land Management](/source/Bureau_of_Land_Management). The ridge contains a diverse selection of rare plants unique to the state of Colorado.

==Geology==

The Raven Ridge and the adjacent parallel Squaw Ridge are northwest [striking](/source/Strike_and_dip) [rock exposures](/source/Outcrop) which provide an opportunity to understand this part of Earth's history. This section through a sequence of rock layers that were deposited between ~53-49 million years ago, has become exposed because of its later [tectonic](/source/tectonic) history. The [outcrop](/source/outcrop)s span the geological time interval that includes the early and middle portions of the [Eocene Epoch](/source/Eocene_Epoch).  During this time, ancestral horses, primates, and rodents, among many other mammal groups, were common at Raven Ridge. At the southern edge of Raven Ridge are found the only available surface coal beds in the area.<ref>{{cite book|author=Geological Survey (U.S.)|title=Bulletin - United States Geological Survey|url=https://archive.org/details/bulletinuniteds70usgoog|year=1910|publisher=The Survey|page=[https://archive.org/details/bulletinuniteds70usgoog/page/n264 208]}}</ref>

The rocks of Raven Ridge were originally deposited on or near a shore line as horizontal sedimentary layers within the [Uinta Basin](/source/Uinta_Basin). [Uplift](/source/Tectonic_uplift) and [folding](/source/Fold_(geology)) associated with the later stages of the [Laramide Orogeny](/source/Laramide_Orogeny) subsequently tilted them into a nearly vertical position.<ref name="nasa"/><ref>
{{Cite journal|doi=10.1306/5D25B7E9-16C1-11D7-8645000102C1865D
|title=AAPG/Datapages, Inc. DOI Citation
|journal=AAPG Bulletin
|volume=51
|publisher=search.datapages.com
|last=Picard 
|first=M. Dane 
|year=1967
}}
</ref>

==Plants==
Raven Ridge is the habitat for eight [endemic](/source/Endemism) rare plant species: ''Penstemon grahamii'' (Graham's beardtongue), ''Penstemon albifluvis'' (White River beardtongue), ''Astragalus lutosus'' (Dragon milkvetch), ''Aquilegia barnebyi'' (Mancos columbine), ''Cryptantha rollinsii'' (Rollins's catseye), ''Parthenium ligulata'' (Colorado feverfew), ''Eriogonum ephedroides'' (ephedra buckwheat), and ''Phacelia incana'' (hoary phacelia).  Numerous other plants are found there as well.<ref name="parks"/><ref>{{cite web|url=http://www.conps.org/pdf/Plant%20Lists/RavenRidgeByGenus.pdf|title=Plants of Raven Ridge, near Rangely, CO, Rio Blanco Co. [Rio Blanco Co(s), Colorado]|publisher=Colorado Native Plant Society|access-date=2009-10-11}}</ref>

==Fossils==
Found at the summit of the ridge are a multitude of perfectly preserved fossil [gastropod](/source/gastropod)s.<ref name="parks">{{cite web
|url=http://parks.state.co.us/NaturalResources/CNAP/NaturalAreasInfo/AlphabeticalListing/RavenRidge.htm
|title=Raven Ridge - Colorado State Parks
|publisher=parks.state.co.us
|access-date=2009-10-11}}</ref>

==References==
{{reflist|22em}}

==External links==
{{commons category|Raven Ridge}}
* {{Cite journal|jstor=3514776|title=Evidence of Reworked Cretaceous Fossils and their Bearing on the Existence of Tertiary Dinosaurs|last=Eaton|first=Jeffrey|year=1989|work=The Society of Economic Paleontologists and Mineralogists|publisher=JSTOR|display-authors=etal|volume=4|pages=281–286|doi=10.2307/3514776}}
* {{cite book|last=Woodburne|first=Michael O.|title=Late Cretaceous and Cenozoic Mammals of North America: Biostratigraphy and Geochronology|url=https://books.google.com/books?id=73ZaLf_LL9cC&pg=PA126|year=2004|publisher=Columbia University Press|isbn=978-0-231-13040-0|page=126}}

{{coord|40|11|22|N|109|03|53|W|display=title}}

{{authority control}}

Category:Paleogene geology
Category:Landforms of Rio Blanco County, Colorado
Category:Landforms of Uintah County, Utah
Category:Bureau of Land Management areas in Colorado
Category:Ridges of Colorado

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Adapted from the Wikipedia article [Raven Ridge](https://en.wikipedia.org/wiki/Raven_Ridge) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Raven_Ridge?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.