Editing Unconformity (section)

==Types==

===Disconformity===
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[[File:Disconformity.jpg|thumb|120px|Disconformity]]
A '''disconformity''' is an unconformity between parallel [[stratum|layers]] of [[sedimentary rocks]] which represents a period of erosion or non-deposition.<ref name="Monroe">{{cite book | url=https://books.google.com/books?id=iXfhFnoQBQ0C&pg=PA267 | title=Physical geology: exploring the Earth | publisher=Cengage Learning | author=Monroe J.S., Wicander R. & Hazlett R.W. | year=2007 | pages=267 | isbn=9780495011484}}</ref> Disconformities are marked by features of [[subaerial]] erosion. This type of erosion can leave channels and [[paleosols]] in the rock record.<ref>{{cite book |last1=Boggs |first1=Sam |title=Principles of sedimentology and stratigraphy |date=2006 |publisher=Pearson Prentice Hall |location=Upper Saddle River, N.J. |isbn=0131547283 |edition=4th |page=405}}</ref>

===Nonconformity===
[[File:Nonconformity.jpg|thumb|120px|Nonconformity]]
A nonconformity exists between sedimentary rocks and [[metamorphic rocks|metamorphic]] or [[igneous rocks]] when the sedimentary rock lies above and was deposited on the pre-existing and eroded metamorphic or igneous rock. Namely, if the rock below the break is igneous or has lost its bedding due to metamorphism, then the plane of juncture is a nonconformity.<ref>{{cite book|last=Stokes|first=W. Lee|title=Essentials of Earth History 4th Edition|publisher=Prentice Hall, Inc.|year=1982|isbn=0-13-285890-8|page=[https://archive.org/details/essentialsofeart0000stok/page/65 65]|url-access=registration|url=https://archive.org/details/essentialsofeart0000stok/page/65}}</ref>

===Angular unconformity===
[[File:Angular unconformity.jpg|thumb|120px|Angular unconformity]]
An angular unconformity is an unconformity where horizontally parallel [[stratum|strata]] of sedimentary rock are deposited on tilted and eroded layers, producing an angular discordance with the overlying horizontal layers.{{sfn|Boggs|2006|pp=404-405}}  The whole sequence may later be deformed and tilted by further [[orogeny|orogenic]] activity. A typical case history is presented by the Briançonnais realm (Swiss and French Prealps) during the Jurassic.<ref>Septfontaine M. (1984): Le Dogger des Préalpes médianes suisses et françaises - stratigraphie, évolution paléogéographique et paléotectonique.- Mém. Soc. Helv. Sci. Nat., vol. 97, 121 p. (Birkhäuser éd.)</ref><ref>Septfontaine M. (1995): Large scale progressive unconformities in Jurassic strata of the Prealps South of lake Geneva: interpretation as synsedimentary inversion structures. Paleotectonic implications. Eclogae geol. Helv., 88:3 553–576.</ref>
<!--[[File:Briançonnais modèles 7F.jpg|thumb|alt= modèles palinspastiques|Block diagrams and profiles of Palinspastic Alps (Briançon sl) Middle Jurassic]][[File:Discordances successives Jurassique Préalpes.jpg|thumb|Successive angular unconformities and fans on the margin N-Briançon, affecting 650m of sediment during 50 Ma; Dogger-Malm, Chablais Alps (Suisse, France).]]-->

Angular unconformities can occur in [[ash fall]] layers of [[pyroclastic rock]] deposited by volcanoes during [[explosive eruption]]s. In these cases, the hiatus in deposition represented by the unconformity may be geologically very short – hours, days or weeks.

===Paraconformity===
[[File:Paraconformity.jpg|thumb|120px|Paraconformity]]
A paraconformity is a type of unconformity in which the sedimentary layers above and below the unconformity are parallel, but there is no obvious erosional break between them. A break in sedimentation is indicated, for example, by fossil evidence. It is also called nondepositional unconformity or pseudoconformity.<ref name="Catuneanu">{{cite book | url=https://books.google.com/books?id=8j-6UTXHmDkC&pg=PA15 | title=Principles of Sequence Stratigraphy | publisher=Elsevier | author=Catuneanu O. | year=2006 | pages=15 | isbn=9780080473987}}</ref><ref>{{cite book | url=https://books.google.com/books?id=irgrAQAAMAAJ&q=pseudoconformity | title=Encyclopedia of Science and Technology: An International Reference Work, Volume 14 | publisher=McGraw-Hill | year=1966 | pages=192}}</ref> Short paraconformities are called [[diastem]]s.{{sfn|Boggs|2006|p=401}}

===Buttress unconformity===
A buttress unconformity, also known as onlap unconformity, occurs when younger bedding is deposited against older strata thus influencing its bedding structure.<ref name="Groshong">{{cite book | url=https://books.google.com/books?id=pvG5BAAAQBAJ&q=%22buttress+unconformity%22&pg=SA1-PA7 | title=3-D Structural Geology: A Practical Guide to Surface and Subsurface Map | publisher=Springer Science & Business Media | author=Groshong R. H. | year=2013 | isbn=9783662039120}}</ref>

===Blended unconformity===
A blended unconformity is a type of disconformity or nonconformity with no distinct separation plane or contact, sometimes consisting of soils, [[paleosol]]s, or beds of pebbles derived from the underlying rock.<ref name="Neuendorf">{{cite book | url=https://books.google.com/books?id=yD79FqfECCYC&pg=PA278 | title=Glossary of Geology | author=Neuendorf K.K.E. | year=2005 | pages=73 | publisher=Springer | isbn=9780922152766}}</ref>