Editing Concretion (section)

===Elongate concretions===
Elongate concretions form parallel to sedimentary strata and have been studied extensively due to the inferred influence of [[phreatic]] (saturated) zone [[groundwater]] flow direction on the orientation of the axis of elongation.<ref>{{cite journal |last1=Johnson |first1=M.R. |title=Paleogeographic Significance of Oriented Calcareous Concretions in the Triassic Katberg Formation, South Africa |journal=SEPM Journal of Sedimentary Research |date=1989 |volume=59 |pages=1008–1010 |doi=10.1306/212F90D9-2B24-11D7-8648000102C1865D}}</ref><ref name=McBride>{{cite journal |last1=McBride |first1=E. F. |last2=Picard |first2=M. D. |last3=Milliken |first3=K. L. |title=Calcite-Cemented Concretions in Cretaceous Sandstone, Wyoming and Utah, U.S.A. |journal=Journal of Sedimentary Research |date=1 May 2003 |volume=73 |issue=3 |pages=462–483 |doi=10.1306/111602730462|bibcode=2003JSedR..73..462M }}</ref><ref>{{cite journal |last1=Mozley |first1=Peter S. |last2=Goodwin |first2=Laurel B. |title=Patterns of cementation along a Cenozoic normal fault: A record of paleoflow orientations |journal=Geology |date=1 June 1995 |volume=23 |issue=6 |pages=539–542 |doi=10.1130/0091-7613(1995)023<0539:POCAAC>2.3.CO;2|bibcode=1995Geo....23..539M }}</ref><ref>{{cite journal |last1=Mozley |first1=Peter S. |last2=Davis |first2=J. Matthew |title=Internal structure and mode of growth of elongate calcite concretions: Evidence for small-scale, microbially induced, chemical heterogeneity in groundwater |journal=Geological Society of America Bulletin |date=2005 |volume=117 |issue=11 |pages=1400 |doi=10.1130/B25618.1|bibcode=2005GSAB..117.1400M }}</ref> In addition to providing information about the orientation of past fluid flow in the host rock, elongate concretions can provide insight into local permeability trends (i.e., permeability correlation structure; variation in groundwater velocity,<ref>{{cite journal |last1=Davis |first1=J. Matthew |title=Oriented carbonate concretions in a paleoaquifer: Insights into geologic controls on fluid flow |journal=Water Resources Research |date=June 1999 |volume=35 |issue=6 |pages=1705–1711 |doi=10.1029/1999WR900042|bibcode=1999WRR....35.1705D |s2cid=129502157 |doi-access=free }}</ref> and the types of geological features that influence flow.

Elongate concretions are well known in the [[Kimmeridge Clay]] formation of northwest Europe. In outcrops, where they have acquired the name "doggers", they are typically only a few meters across, but in the subsurface they can be seen to penetrate up to tens of meters of along-hole dimension. Unlike limestone beds, however, it is impossible to consistently correlate them between even closely spaced wells.{{citation needed|date=May 2010}}