|Geologic age||Middle Ordovician|
Sedimentary > Clastic > Mudstone > Shale > Black-shale
|Comments||part of Lorraine, Trenton, and Black River Groups up to 1600 ft. (490 m). Secondary unit description from USGS Lexicon website (ref. NY046) and reference NY036: The Utica Shale is divided in the Mohawk Valley into upper and lower parts by a tongue of the Dolgeville Formation and these parts are here assigned member names. The lower portion of the Utica is named the Flat Creek Member and the upper, the Indian Castle Member. These lithostratigraphic units replace earlier names such as the Canajoharie Shale, which are primarily biostratigraphic. Revised stratigraphic correlations based on reinterpretation of graptolites and K-bentonites in the area suggest that the lower part of the Utica Shale is the lateral equivalent of a large part of the lower Trenton Group and is older than the Denley Limestone, with which it has been previously equated. The Flat Creek Member overlies the early to middle Kirkfieldian Kings Falls Limestone of the Trenton Group at Canajoharie Creek and interfingers with the Sugar River Limestone of the Trenton Group to the west. The Trenton-Utica succession is a transgressive sequence. Westward, the Dolgeville grades into the lower Denley and the Utica (equivalent to only the upper Utica of the east) disconformably overlies the Denley and Steuben Limestones of the Trenton Group. The Utica underlies the Frankfort Formation throughout the study area. Age of the Utica between Chuctanunda Creek and Caroga Creek, ranges from Kirkfieldian (Mohawkian) to Edenian (Cincinnatian). Formation youngs westward and at Trenton Falls the entire unit is shown as Maysvillian (Cincinnatian). The following figure is adapted from Fig. 14 of Goldman and others (1994). Their cross-section shows age and facies relationships of the Utica Shale, Trenton Group, and adjacent units. The columns shown here were extracted from that diagram in an attempt to show the time transgressive nature of the Utica and the stratigraphic position of its newly named members. Ages and relationships are approximate. Dashed lines are used where contacts are gradational or interfingering.|
Fisher, D.W., Isachsen, Y.W., and Rickard, L.V., 1970, Geologic Map of New York State, consisting of 5 sheets: Niagara, Finger Lakes, Hudson-Mohawk, Adirondack, and Lower Hudson, New York State Museum and Science Service, Map and Chart Series No. 15, scale 1:250,000.
Goldman, Daniel, Mitchell, C.E., Bergstrom, S.M., Delano, J.W. and Tice, Steven, 1994, K-bentonites and graptolite biostratigraphy in the Middle Ordovician of New York State and Quebec; a new chronostratigraphic model: Palaios, v. 9, no. 2, p. 124-143.
USGS Geologic Names lexicon found at: http://ngmdb.usgs.gov/Geolex/
|Counties||Fulton - Herkimer - Jefferson - Lewis - Montgomery - Oneida - Oswego - Otsego - Schoharie|