# Midland Formation
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{{Short description|Mesozoic formation in Virginia, United States}}
{{Infobox rockunit
| name = Midland Formation
| image =
| caption =
| type = [Geological formation](/source/Geological_formation)
| age =
[Late Triassic](/source/Late_Triassic) to [Early Jurassic](/source/Early_Jurassic),
late [Rhaetian](/source/Rhaetian) to early [Hettangian](/source/Hettangian)
| prilithology = [sandstone](/source/sandstone), [siltstone](/source/siltstone)
| otherlithology = [shale](/source/shale), [limestone](/source/limestone)
| namedfor = [Midland, Virginia](/source/Midland%2C_Virginia)
| namedby = Lee & Froelich, 1989
| region = [Maryland](/source/Maryland), [Virginia](/source/Virginia)
| country = [United States](/source/United_States)
| coordinates =
| unitof = [Meriden Group](/source/Meriden_Group)
| subunits =
| underlies = [Hickory Grove Basalt](/source/Hickory_Grove_Basalt)
| overlies = [Mount Zion Church Basalt](/source/Mount_Zion_Church_Basalt)
| thickness =
| extent = [Culpeper Basin](/source/Culpeper_Basin)
| area =
| map =
| map_caption =
|period=Hettangian}}
The '''Midland Formation''' is a [Mesozoic](/source/Mesozoic) (latest [Triassic](/source/Triassic) to earliest [Jurassic](/source/Jurassic)) [geological formation](/source/geological_formation) in the [Culpeper Basin](/source/Culpeper_Basin) of [Virginia](/source/Virginia). It is a [sedimentary](/source/Sedimentary_rock) unit which formed in a short period of time between the first two [basalt](/source/basalt) flows in the basin: the [Hickory Grove](/source/Hickory_Grove_Basalt) and [Mount Zion Church](/source/Mount_Zion_Church_Basalt) basalts. The most common rocks in the formation are dark reddish [interbedded](/source/Interbedding) [sandstones](/source/Sandstone) and [siltstones](/source/Siltstone), representative of fluvial (stream) environments. Rare but fossiliferous [calcareous](/source/calcareous) [shale](/source/shale) and [limestone](/source/limestone) also occurs, representing recurring lacustrine (lake) conditions.[{{Cite journal|last1=Weems|first1=Robert E.|last2=Olsen|first2=Paul E.|date=1997-02-01|title=Synthesis and revision of groups within the Newark Supergroup, eastern North America|url=https://www.researchgate.net/publication/40661805|journal=GSA Bulletin|language=en|volume=109|issue=2|pages=195–209|doi=10.1130/0016-7606(1997)109<0195:SAROGW>2.3.CO;2 |bibcode=1997GSAB..109..195W |issn=0016-7606}}][{{Cite journal|last1=Weems|first1=Robert E.|last2=Tanner|first2=Lawrence H.|last3=Lucas|first3=Spencer G.|date=2016|title=Synthesis and revision of the lithostratigraphic groups and formations in the Upper Permian?–Lower Jurassic Newark Supergroup of eastern North America|url=https://www.researchgate.net/publication/309853816|journal=Stratigraphy|language=en|volume=13|issue=2|pages=111–153 |doi=10.29041/strat.13.2.03 }}] Some sources prefer to classify the Midland Formation as part of the Shuttle Meadow Formation.[{{Cite journal |last1=Olsen |first1=P. E. |last2=McCune |first2=A. R.|author2-link=Amy McCune |last3=Thomson |first3=K. S. |date=1982-01-01 |title=Correlation of the early Mesozoic Newark Supergroup by vertebrates, principally fishes |url=https://www.researchgate.net/publication/242164729 |journal=American Journal of Science |volume=282 |issue=1 |pages=1–44 |doi=10.2475/ajs.282.1.1 |issn=0002-9599|doi-access=free |bibcode=1982AmJS..282....1O }}][{{Cite journal|last1=Kozur|first1=Heinz W.|last2=Weems|first2=Robert E.|date=2010-01-01|title=The biostratigraphic importance of conchostracans in the continental Triassic of the northern hemisphere|url=http://www.keuper.us.edu.pl/02_Keuper-literature/Kozur%20&%20Weems-2010_GSLondon.pdf|journal=Geological Society, London, Special Publications|language=en|volume=334|issue=1|pages=315–417|doi=10.1144/SP334.13|bibcode=2010GSLSP.334..315K |issn=0305-8719|s2cid=131224365}}][{{Cite journal|last1=Lucas|first1=S.G.|last2=Tanner|first2=L.H.|last3=Donohoo-Hurley|first3=L.L.|last4=Geissman|first4=J.W.|last5=Kozur|first5=H.W.|last6=Heckert|first6=A.B.|last7=Weems|first7=R.E.|date=2011-03-15|title=Position of the Triassic–Jurassic boundary and timing of the end-Triassic extinctions on land: Data from the Moenave Formation on the southern Colorado Plateau, USA|url=https://www.sciencedirect.com/science/article/abs/pii/S0031018211000125|journal=Palaeogeography, Palaeoclimatology, Palaeoecology|language=en|volume=302|issue=3–4|pages=194–205|doi=10.1016/j.palaeo.2011.01.009|bibcode=2011PPP...302..194L |issn=0031-0182|url-access=subscription}}] A prominent shale layer containing [Hettangian](/source/Hettangian)-age fossilized fish, the Midland fish bed, is present about 10 meters above the base of the formation. Though now flooded by a manmade lake, it was formerly well-exposed along Licking Run, just north of [Midland, Virginia](/source/Midland%2C_Virginia).[{{Cite journal |last1=Baer |first1=Francis M. |last2=Martin |first2=William H. |date=1949-12-23 |title=Some New Finds of Fossil Ganoids in the Virginia Triassic |url=http://dx.doi.org/10.1126/science.110.2869.684 |journal=Science |volume=110 |issue=2869 |pages=684–686 |doi=10.1126/science.110.2869.684 |issn=0036-8075 |jstor=1677051|pmid=15396741 |bibcode=1949Sci...110..684B |url-access=subscription }}][{{Cite journal |last1=Schaeffer |first1=Bobb |last2=McDonald |first2=Nicholas G. |date=1978 |title=Redfieldiid fishes from the Triassic-Liassic Newark Supergroup of eastern North America |url=https://digitallibrary.amnh.org/items/52d8aa67-6a45-4f02-b887-e7e3094c401d |journal=Bulletin of the American Museum of Natural History |volume=159 |issue=4 |pages=131–173}}][{{Cite journal|last=Weems|first=Robert E.|date=2018|title=A synopsis of the vertebrate fauna from the Culpeper Basin (Upper Triassic-Lower Jurassic, Maryland and Virginia)|url=https://www.researchgate.net/publication/348579482|journal=New Mexico Museum of Natural History and Science Bulletin|volume=79|pages=749–768}}] Plant spores,[{{Cite journal|last1=Lee|first1=K.Y.|last2=Froelich|first2=A.J.|date=1989|title=Triassic- Jurassic Stratigraphy of the Culpeper and Barboursville Basins, Virginia and Maryland|url=https://pubs.er.usgs.gov/publication/pp1472|journal=U.S. Geological Survey Professional Paper|volume=1472|pages=1–52|doi=10.3133/pp1472}}] [coprolites](/source/Coprolite),[{{Cite book |last=Olsen |first=Paul E. |title=Triassic-Jurassic Rifting and the Opening of the Atlantic Ocean |publisher=Elsevier |year=1988 |editor-last=Manspeizer |editor-first=Warren |location=Amsterdam |pages=185–230 |chapter=8. Paleoecology and Paleoenvironments of the Continental Early Mesozoic Newark Supergroup of Eastern North America |doi=10.1016/B978-0-444-42903-2.50013-0 |chapter-url=https://www.ldeo.columbia.edu/~polsen/nbcp/olsen_88.pdf}}][{{Cite journal |last1=Olsen |first1=P. E. |last2=Kent |first2=D. V. |last3=Sues |first3=H.-D. |last4=Koeberl |first4=C. |last5=Huber |first5=H. |last6=Montanari |first6=A. |last7=Rainforth |first7=E. C. |last8=Fowell |first8=S. J. |last9=Szajna |first9=M. J. |last10=Hartline |first10=B. W. |date=2002-05-17 |title=Ascent of Dinosaurs Linked to an Iridium Anomaly at the Triassic-Jurassic Boundary |url=https://www.science.org/doi/10.1126/science.1065522 |journal=Science |language=en |volume=296 |issue=5571 |pages=1305–1307 |doi=10.1126/science.1065522 |pmid=12016313 |bibcode=2002Sci...296.1305O |issn=0036-8075|url-access=subscription }}][Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.]