outcrop
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An outcrop or rocky outcrop is a visible exposure of
bedrock Bedrock in geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of which it is composed, and ...
or ancient
superficial deposits Superficial deposits refer to geological deposits typically of Quaternary Quaternary ( ) is the current and most recent of the three Period (geology), periods of the Cenozoic Era (geology), Era in the geologic time scale of the International Comm ...
on the surface of the Earth.


Features

Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial deposits are covered by a mantle of
soil File:Stagnogley.JPG, Surface-water-Gley soil, gley developed in glacial till, Northern Ireland. Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth's body of soil, called the pedosphere ...

soil
and vegetation and cannot be seen or examined closely. However, in places where the overlying cover is removed through
erosion In earth science, erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust, and then sedime ...

erosion
or
tectonic uplift Kupe's Sail at Palliser Bay in New Zealand Tectonic uplift is the orogeny, geologic uplift of Earth#Surface, Earth's surface that is attributed to plate tectonics. While isostatic response is important, an increase in the mean elevation of a r ...
, the rock may be exposed, or ''crop out''. Such exposure will happen most frequently in areas where
erosion In earth science, erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust, and then sedime ...

erosion
is rapid and exceeds the
weathering Weathering is the deterioration of rocks A rock is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition and the way in wh ...
rate such as on steep hillsides, mountain ridges and tops, river banks, and tectonically active areas. In
Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the west, Russia to the east, Norway to the north, and is defined by the Gulf of Bo ...

Finland
,
glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age#REDIRECT Ice age {{Redirect category shell, 1= {{R from move {{R from ambiguous term {{R from other capitalisation {{R unprintwor ...

glacial
erosion during the last glacial maximum (ca. 11000 BC), followed by scouring by sea waves, followed by
isostatic upliftThe term isostatic may refer to: *Isostatic depression in geodynamics *Isostatic powder compaction in metallurgy and ceramic engineering *Isostatic press in manufacturing See also

*Isostasy in geology: gravitational equilibrium between the e ...
has produced many smooth coastal and littoral outcrops. Bedrock and superficial deposits may also be exposed at the Earth's surface due to human excavations such as quarrying and building of transport routes.


Study

Outcrops allow direct observation and sampling of the
bedrock Bedrock in geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (geology), rocks of which it is composed, and ...
''
in situ ''In situ'' (; often not italicized in English) is a Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, known as ...

in situ
'' for
geologic Geology (from the Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following peri ...

geologic
analysis and creating
geologic map A geologic map is a special-purpose map made to show various geological features. Rock units or geologic strata are shown by color or symbols. Bedding planes and structural features such as faults, folds, are shown with strike and dip St ...
s. In situ measurements are critical for proper analysis of geological history and outcrops are therefore extremely important for understanding the
geologic time scale The geologic time scale (GTS) is a system of chronological datingChronological dating, or simply dating, is the process of attributing to an object or event a date in the past, allowing such object or event to be located in a previously establish ...

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 Structural geology is the study of the three-dimensional distribution of Rock (geology), rock units with respect to their Deformation (geology), deformational histories. The primary goal of structural geology is to use measurements of present-day ...
features orientations (e.g. bedding planes,
fold Fold or folding may refer to: Arts, entertainment, and media *Fold (album), ''Fold'' (album), the debut release by Australian rock band Epicure *Fold (poker), in the game of poker, to discard one's hand and forfeit interest in the current pot *Ab ...
axes,
foliation In mathematics Mathematics (from Ancient Greek, Greek: ) includes the study of such topics as quantity (number theory), mathematical structure, structure (algebra), space (geometry), and calculus, change (mathematical analysis, analysis). ...
), depositional features orientations (e.g. paleo-current directions, grading,
facies carbonate facies (Holocene) on Long Island, Bahamas Long Island is an island in the Bahamas that is split by the Tropic of Cancer. It is one of the Districts of the Bahamas and is known as the most scenic island in the Bahamas. Its capital is Clar ...
changes),
paleomagnetic Paleomagnetism, or palaeomagnetism, is the study of the record of the Earth's magnetic field Earth's magnetic field, also known as the geomagnetic field, is the magnetic field A magnetic field is a vector field that describes the magnet ...
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
strata (Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country located mostly in the southern half of South America. Sharing the bulk of the Southern Cone with Chile to the west, the country is ...
. 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#REDIRECT Law of superposition 250px, Layer upon layer of rocks on north shore of Isfjord (Svalbard), Isfjord, Svalbard, Norway. Since there is no overturning, the rock at the bottom is older than the rock on the top by the Law of Superposition. ...

law of superposition
, the
principle of original horizontality The Principle of Original Horizontality states that layers of sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently sediment transport, transported by the action of wi ...
,
principle of lateral continuity 300px, The Permian through Jurassic strata of the Colorado Plateau">Jurassic.html" ;"title="Permian through Jurassic">Permian through Jurassic strata of the Colorado Plateau area of southeastern Utah that makes up much of the famous prominent rock ...
, and the
principle of faunal succession The principle of faunal succession, also known as the law of faunal succession, is based on the observation that sedimentary rock strata contain fossil A fossil (from Classical Latin: , literally "obtained by digging") is any preserved r ...
.


Examples

On
Ordnance Survey , nativename_a = , nativename_r = , logo = Ordnance Survey 2015 Logo.svg , logo_width = 240px , logo_caption = , seal = , seal_width = , seal_caption = , picture = , picture_width = , picture_caption = , formed = , preceding1 = , dis ...
maps in
Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the List of European islands by area, largest European island, and the List of i ...

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 California is a U.S. state, state in the Western United States. With over 39.3million residents across a total area of approximately , it is the List of states and territories of the United States by population, most populous and the List of ...

California
is the
Vasquez Rocks Vasquez Rocks Natural Area Park is a park located in the Sierra Pelona Mountains The Sierra Pelona, also known as the Sierra Pelona Ridge or the Sierra Pelona Mountains, is a mountain ridge in the Transverse Ranges The Transverse Ranges are a gr ...

Vasquez Rocks
, familiar from
location shooting Location shooting is the shooting of a film A film, also called a movie, motion picture or moving picture, is a work of visual art used to simulate experiences that communicate ideas, stories, perceptions, feelings, beauty, or atmosphere ...
use in many
films A film, also called a movie, motion picture or moving picture, is a work of visual art The visual arts are art forms such as painting Painting is the practice of applying paint, pigment, color or other medium to a solid surface ...

films
, composed of uplifted
sandstone Sandstone is a clastic sedimentary rock of a clast (sand grain), derived from a basalt Basalt (, ) is a fine-grained extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron ('' mafic '' ...

sandstone
.parks.lacounty.gov. Vazquez Rocks Natural Area and Nature Center. access date:5/22/2010
/ref> Yana is another example of outcrops, located in
Uttara Kannada Uttara Kannada, formerly known as North Canara, is a district in the Indian states and territories of India, state of Karnataka. It is bordered by the state of Goa and Belagavi District to the north, Dharwad District and Haveri District to the ea ...
district in
Karnataka Karnataka (ISO 15919, ISO: , ) is a States of India, state in the south western region of India. It is the largest state in South India and sixth largest in India. It was Unification of Karnataka, formed on 1 November 1956, with the passage of ...

Karnataka
,
India India (Hindi: ), officially the Republic of India (Hindi: ), is a country in South Asia. It is the List of countries and dependencies by population, second-most populous country, the List of countries and dependencies by area, seventh-largest ...

India
. File:Serrotebranco.JPG, Serrote Branco outcrop in Caicó,
Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, ...

Brazil
File:Granodiorite of the Fennoscandian Shield.jpg,
Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of History of the Earth, Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the ...

Precambrian
outcrop in Finland File:Śląskie Kamienie - Dívči Kameny.JPG,
Granite Granite () is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools ...

Granite
outcrops at 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 California is a U.S. state, state in the Western United States. With over 39.3million residents across a total area of approximately , it is the List of states and territories of the United States by population, most populous and the List of ...

California


See also

*Digital outcrop model *Geological formation *Geologic time scale *List of rock formations


References


External links

* * {{Authority control Rock formations Rocks