Lockport Group
{{Infobox rockunit
| name = Lockport Group
| image =
| caption =
| type = Group
| age = Sheinwoodian-Homerian
~{{Fossil range|433|427}}
| prilithology =Dolomite
| otherlithology =Limestone, Chert
| namedfor =
| namedby =
| region = New York, Ohio, Pennsylvania, West Virginia, Ontario
| country = United States, Canada
| coordinates =
| unitof =Cayugan Series
| subunits =*Guelph Formation
| underlies =Vernon Formation
| overlies =Clinton Group
| thickness =
| extent =Appalachian Basin, Michigan Basin
| area =
| map =
| map_caption =
|period=Upper Silurian}}
The Lockport Group is a geologic group in the Appalachian Basin and Michigan Basin in the northeastern United States and Canada. This unit makes up the Niagara Escarpment. Its most famous feature is Niagara Falls. The unit outcrops in New York, Ontario, Michigan, Wisconsin, and Illinois.{{Cite book |last=Kelly |first=Peter E. |url=https://www.worldcat.org/oclc/768163291 |title=The last stand : a journey through the ancient cliff-face forest of the Niagara Escarpment |date=2007 |publisher=Natural Heritage Books |others=Douglas W. Larson |isbn=978-1-55488-332-5 |location=Toronto |oclc=768163291}}
Description
The Lockport Group is made up of four formations. From base to top: Gasport Formation, Goat Island Formation, Eramosa Formation and Guelph Formation. The entire unit is composed of dolomite, with the exception of the Gasport which can be limestone, as well as occasional chert nodules.{{Cite web |last=Tepper |first=Dorothy H. |last2=Goodman |first2=William M. |last3=Gross |first3=Michael R. |last4=Kappel |first4=William M. |last5=Yager |first5=Richard M. |title=Stratigraphy, Structural Geology, and Hydrogeology of the Lockport Group: Niagara Falls Area, New York |url=https://www.nysga-online.org/wp-content/uploads/2019/06/NYSGA-1990-SunB-Stratigraphy-Structure-And-Hydrogeology-Of-The-Lockport-Group-Niagara-Falls-Area-New-York.pdf |access-date=9 April 2023 |website=New York State Geological Association Online}}
Stratigraphy
{{inline citations needed|section|date=July 2024}}
The Guelph Formation is at the top of the Lockport Group. It has been called the "Vernon Transition Zone" due to thin beds and laminations between carbonates, claystones and evaporates. Its base is delimited by a stromatolite bed.
Below the Guelph is the Eramosa Formation. This formation is typically a thinly laminated packstone and grainstone. There are stromatolite beds as well as corals preserved in this formation. Near the base the unit becomes vuggy. Again the top of this formation is marked by a sharp change between grainstone and a stromatolite bed.
== References ==
Category:Geologic groups of New York (state)
Category:Silurian West Virginia
Category:Silurian geology of Pennsylvania
Category:Geologic groups of Pennsylvania
Category:Geologic groups of Ohio
Category:Geologic groups of West Virginia
Category:Geologic groups of Ontario
Category:Limestone groups of the United States