{{Short description|Visible exposure of bedrock or ancient superficial deposits on the surface of the Earth}} {{More citations needed|date=September 2011}} [[File:Rockeskyller Kopf 3.JPG|thumb|Outcrop of volcanic rock in Germany]] An '''outcrop''' or '''rocky outcrop''' is a visible exposure of [[bedrock]] or ancient [[superficial deposits]] on the surface of the Earth and other [[terrestrial planets]].<ref>Howell, J. V., 1960, ''Glossary of Geology and Related Sciences''. Washington, DC: American Geological Institute, pp. 207–208</ref>

==Features==

In most places, bedrock or superficial deposits are covered by [[soil]] and vegetation. Where these are removed through [[erosion]], [[tectonic uplift]], or excavation by humans, the underlying rock may ''crop out'', or be exposed. Most frequently, this occurs on steep hillsides, mountain ridges and mountaintops, river banks, and areas which are tectonically active. For example, [[Finland]] has many coastal and [[littoral]] outcrops due to [[Glacier|glacial]] erosion during the last glacial maximum ({{Circa}} 11000 BC), followed by scouring by sea waves, then [[Postglacial rebound|isostatic uplift]].

==Study== Outcrops allow direct observation and sampling of the [[bedrock]] ''[[in situ]]'' for [[Geology|geologic]] analysis and creating [[geological map]]s. In situ measurements are critical for proper analysis of [[Historical geology|geological history]] and outcrops are therefore extremely important for understanding the [[geologic time scale]] of earth history. Some of the types of information that cannot be obtained except from bedrock outcrops or by precise drilling and coring operations, are [[structural geology]] features orientations (e.g. bedding planes, [[fold (geology)|fold]] axes, [[Foliation (geology)|foliation]]), depositional features orientations (e.g. paleo-current directions, grading, [[facies]] changes), [[paleomagnetic]] orientations. Outcrops are also very important for understanding fossil assemblages, and paleo-environment, and evolution as they provide a record of relative changes within geologic [[stratum|strata]].

Accurate description, mapping, and sampling for laboratory analysis of outcrops made possible all of the geologic sciences and the development of fundamental geologic laws such as the [[law of superposition]], the [[principle of original horizontality]], [[principle of lateral continuity]], and the [[principle of faunal succession]].

== Types of outcrops == Outcrops occur in numerous forms, including, but not limited to:<ref>{{Cite journal |last=Fitzsimons |first=James A. |last2=Michael |first2=Damian R. |date=2017-07-01 |title=Rocky outcrops: A hard road in the conservation of critical habitats |url=https://www.sciencedirect.com/science/article/abs/pii/S0006320716308473 |journal=Biological Conservation |series=Small Natural Features |volume=211 |pages=36–44 |doi=10.1016/j.biocon.2016.11.019 |issn=0006-3207|url-access=subscription }}</ref>

* [[Cliff|Cliffs]] * [[Tor (rock formation)|Tors]] * [[Escarpment|Escarpments]] * [[Inselberg|Inselbergs]]

==Examples== On [[Ordnance Survey]] maps in [[Great Britain]], cliffs are distinguished from outcrops: cliffs have a continuous line along the top edge with lines protruding down; outcrops have a continuous line around each area of bare rock. An outcrop example in [[California]] is the [[Vasquez Rocks]], familiar from [[location shooting]] use in many [[movie|films]], composed of uplifted [[sandstone]].<ref>{{Cite web |url=http://employees.oxy.edu/jerry//vazquez.htm |title=oxy.edu. Vazquez Rocks. access date:5/22/2010 |access-date=2010-05-24 |archive-url=https://web.archive.org/web/20110608223233/http://employees.oxy.edu/jerry//vazquez.htm |archive-date=2011-06-08 |url-status=dead }}</ref><ref>{{Cite web |url=http://parks.lacounty.gov/Parkinfo.asp?URL=cms1_033383.asp&Title=Vasquez%20%20Rocks%20Natural%20Area%20and%20Center |title=parks.lacounty.gov. Vazquez Rocks Natural Area and Nature Center. access date:5/22/2010 |access-date=2010-05-24 |archive-date=2012-09-20 |archive-url=https://web.archive.org/web/20120920004535/http://parks.lacounty.gov/Parkinfo.asp?URL=cms1_033383.asp&Title=Vasquez%20%20Rocks%20Natural%20Area%20and%20Center |url-status=dead }}</ref> [[Yana, India|Yana]] is another example of outcrops, located in [[Uttara Kannada]] district in [[Karnataka]], [[India]]. <gallery mode="packed" heights="150"> File:Serrotebranco.JPG|Serrote Branco outcrop in [[Caicó]], [[Brazil]] File:Granodiorite of the Fennoscandian Shield.jpg|[[Precambrian]] outcrop in Finland File:Śląskie Kamienie - Dívči Kameny.JPG|[[Granite]] outcrops at [[Śląskie Kamienie|Silesian Stones]] Mountain in southwestern [[Poland]] File:Yana Rock no border.jpg|Outcrop near [[Yana, India]] File:Roubidoux sandstone bluff.JPG|Outcrop of the [[Roubidoux Formation]] in the [[Ozarks]] of southern [[Missouri]] File:Vasquez Rocks County Park.jpg|Outcrop in the [[Vasquez Rocks Natural Area Park]] of southern [[California]] File:12 1072m - Valley of Desolation.jpg|Valley of Desolation in the [[Camdeboo National Park]] </gallery>

== See also ==

{{portal|Earth sciences}} * {{annotated link|Digital outcrop model}} * {{annotated link|Geological formation}} * {{annotated link|Geologic time scale}} * {{annotated link|List of rock formations}} * {{annotated link|Subcrop}} * {{annotated link|Floater (geology)}}

==References== {{Reflist}}

==External links== {{Commons}} * {{Wiktionary-inline}}

{{Authority control}}

[[Category:Rock formations]] [[Category:Rocks]]