Editing Concretion (section)

===Hiatus concretions===
[[Image:OrdovicianEdrio.jpg|thumb|Hiatus concretion encrusted by bryozoans (thin, branching forms) and an [[edrioasteroid]]; [[Kope Formation]] (Upper Ordovician), northern [[Kentucky]]]]
[[Image:HiatusConcretionsIsrael060910.jpg|thumb|Hiatus concretions at the base of the [[Menuha Formation]] (Upper Cretaceous), the [[Negev]], southern [[Israel]]]]
Hiatus concretions are distinguished by their stratigraphic history of exhumation, exposure and reburial. They are found where submarine erosion has concentrated early diagenetic concretions as [[Lag deposit|lag surface]]s by washing away surrounding fine-grained sediments.<ref name=Zaton/> Their significance for stratigraphy, sedimentology and paleontology was first noted by Voigt who referred to them as ''Hiatus-Konkretionen''.<ref>{{cite journal |last1=Voigt |first1=Ehrhard |title=Über Hiatus-Konkretionen (dargestellt an Beispielen aus dem Lias) |journal=Geologische Rundschau |date=October 1968 |volume=58 |issue=1 |pages=281–296 |doi=10.1007/BF01820609|bibcode=1968GeoRu..58..281V |s2cid=128842746 }}</ref> "Hiatus" refers to the break in sedimentation that allowed this erosion and exposure. They are found throughout the fossil record but are most common during periods in which [[calcite sea]] conditions prevailed, such as the [[Ordovician]], [[Jurassic]] and [[Cretaceous]].<ref name=Zaton>{{cite journal |last1=Zatoń |first1=Michał |title=Hiatus concretions |journal=Geology Today |date=24 September 2010 |volume=26 |issue=5 |pages=186–189 |doi=10.1111/j.1365-2451.2010.00762.x|bibcode=2010GeolT..26..186Z |s2cid=247665440 }}</ref> Most are formed from the cemented infillings of burrow systems in siliciclastic or carbonate sediments.

A distinctive feature of hiatus concretions separating them from other types is that they were often encrusted by marine organisms including [[bryozoans]], [[echinoderms]] and [[Tube worm (body plan)|tube worms]] in the Paleozoic<ref>{{cite journal |last1=Wilson |first1=M. A. |title=Disturbance and Ecologic Succession in an Upper Ordovician Cobble-Dwelling Hardground Fauna |journal=Science |date=3 May 1985 |volume=228 |issue=4699 |pages=575–577 |doi=10.1126/science.228.4699.575|pmid=17736081 |bibcode=1985Sci...228..575W |s2cid=28818298 }}</ref> and bryozoans, [[oysters]] and tube worms in the Mesozoic and Cenozoic. Hiatus concretions are also often significantly [[bioerosion|bored]] by worms and bivalves.<ref name=Wilson>{{cite journal |last1=Wilson |first1=Mark A. |last2=Taylor |first2=Paul D. |title=Palaeocology of Hard Substrate Faunas from the Cretaceous Qahlah Formation of the Oman Mountains |journal=Palaeontology |date=February 2001 |volume=44 |issue=1 |pages=21–41 |doi=10.1111/1475-4983.00167|bibcode=2001Palgy..44...21W |s2cid=129664357 |doi-access=free }}</ref>