Clinton Group

{{short description|Lithostratigraphic unit}}

{{Infobox rockunit

| name = Clinton Group

| period = Early Silurian

| image = Port Clinton, PA - bedrock outcrop.jpg

| caption = Rocks of the Clinton Group on the east face of Schuylkill Gap

| type = Geological formation

| prilithology = sandstone, shale, and limestone

| otherlithology = Ironstone and conglomerate,

| namedfor = Clinton, New York

| namedby = Lardner Vanuxem (1842)

| region = Appalachian Basin of eastern North America

| country = United States

| coordinates =

| unitof =

| subunits = Rochester Shale, Rose Hill Formation, Keefer Formation

| underlies = Bloomsburg Formation in Pennsylvania, Lockport Group in New York

| overlies = Tuscarora Formation in Pennsylvania, Clinch Formation in Virginia, Tennessee, and Maryland, Medina Group in New York

| thickness = 1640 ft

| extent = Ohio, Pennsylvania, Maryland, New York, West Virginia

| area =

| map =

| map_caption =

}}

The Clinton Group (also referred to as the Clinton Formation or the Clinton Shale) is a mapped unit of sedimentary rock found throughout eastern North America.{{cite book

|author1=Brett, C.E. |author2=Baarli, B.G. |author3=Chowns, T. |author4=Cotter, E. |author5=Driese, S. |author6=Goodman, W. |author7=Johnson, M.E. | year = 1998

| chapter = Early Silurian Condensed Intervals, Ironstones, and Sequence Stratigraphy in the Appalachian Foreland Basin

| title = Silurian Cycles: Linkages of Dynamic Stratigraphy with Atmospheric, Oceanic and Tectonic Changes. James Hall Centennial Volume. New York State Museum Bulletin

| volume = 491

|editor= Landing, E. |editor2=Johnson, M.E.

| pages = 89–143

}}{{cite web |url=http://ngmdb.usgs.gov/ngm-bin/count_pub_refs.pl?publisher=USGS&url=%2FGeolex%2FNewUnits%2Funit_1111.html&refer=%2FProdesc%2Fproddesc_1124.htm&ref_type=g |title= Clinton Group, Group|accessdate=2012-10-05 |format= |work=National Geologic Map Database}} The interval was first defined by the geologist Lardner Vanuxem, who derived the name from the village of Clinton in Oneida County, New York where several well exposed outcrops of these strata can be found.{{cite book

| author = Vanuxem, L.

| year = 1839

| chapter = Third Annual Report of the Geological Survey of the Third District

| title = New York State Geological Survey Annual Report

| volume = 3

| pages = 241–285

}}{{cite book

| author = Gillette, T.

| year = 1947

| chapter = The Clinton of Western and Central New York

| title = New York State Museum Bulletin

| volume = 341

| pages = 1–191

| publisher = The University of the State of New York

| location = Albany, New York

| chapter-url = http://128.121.13.244:8080/awweb/main.jsp?flag=browse&smd=1&awdid=1

}} The Clinton Group and its lateral equivalents extend throughout much of the Appalachian Foreland Basin, a major structural and depositional province extending from New York to Alabama. The term has been employed in Kentucky, Maryland, Michigan, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia, though in many of these areas the same interval is referred to as the Rose Hill, Rockwood, or Red Mountain Formations.{{cite journal

|author1=Brett, C.E. |author2=Goodman, W.M. |author3=LoDuca, S.T. | year = 1990

| title = Sequences, cycles, and basin dynamics in the Silurian of the Appalachian Foreland Basin

| journal = Sedimentary Geology

| volume = 69

|issue=3–4 | pages = 191–244

| doi=10.1016/0037-0738(90)90051-T

|bibcode=1990SedG...69..191B }} Historically the term "Clinton" has also been assigned to several lower Silurian stratigraphic units in Ohio and Kentucky which are now known to be significantly older than the Clinton Group as it was originally defined.{{cite journal

|author1=Rexroad, C.B. |author2=Branson, E.R. |author3=Smith, M.O. |author4=Summerson, C. |author5=Boucot, A.J. | year = 1965

| title = The Silurian Formations of East-Central Kentucky and Adjacent Ohio

| journal = Kentucky Geological Survey, Series X

| volume = 2

| pages = 1–34

}} Many parts of this succession are richly fossiliferous, making the Clinton Group an important record of marine life during the early Silurian. Several economically valuable rock-types are found within this interval, though it is perhaps best known as a significant source of iron ore {{cite web |url=http://www.clintonhistory.org/A019.html |title= Iron Ore Mining and Manufacturing in the Town of Kirkland |accessdate=2012-10-05 |work=Lecture at the Clinton Historical Society meeting on April 16, 1998 at the Society's Headquarters on Fountain Street, Clinton, New York}}

Stratigraphically, the Clinton Group overlies the coarse siliciclastics of the Medina Group in New York, The Albion Group in the Subsurface of Ohio, the Clinch Sandstone in Virginia and West Virginia, and the Tuscarora Sandstone in Pennsylvania. It is overlain by the shales and carbonates of the Lockport Group in New York, the McKenzie Formation in Pennsylvania, and the Sneedville Limestone in Tennessee. Owing to the great difference in resistivity between the relatively soft, readily weathering Clinton Group and the massive dolomites of the overlying Lockport, the former tends to erode preferentially out from underneath the latter. This has resulted in the formation of numerous cateracts such as Niagara Falls and the High Falls of Rochester, New York which are but local manifestations of a regional geographic feature called the Niagara Escarpment.{{Cite web |url=http://www.uwgb.edu/dutchs/GeologyWisconsin/niagesc.htm |title=The Niagara Escarpment |access-date=2012-10-05 |archive-url=https://web.archive.org/web/20100604132605/http://www.uwgb.edu/dutchs/GeologyWisconsin/niagesc.htm |archive-date=2010-06-04 |url-status=dead }}