Clinton Group
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.
Description
The Clinton Group (or Formation) is a widely traceable, lower Silurian lithostratigraphic unit composed primarily of shale and mudstone, though it encompasses a heterogeneous assemblage of sedimentary rock types, including conglomerate, sandstone, limestone, dolomite, and ironstone. In its designated type area in Clinton, Oneida County, New York the unit is approximately 50 meters (180 feet) thick, and composed primarily of blue-grey mudstone, shale, and sandstone with several discrete ferruginous horizons, known colloquially as "Clinton Ironstones". The lateral equivalent of these beds to the south is the Rose Hill Formation of Pennsylvania, and olive-gray to drab, thin-bedded sandstone.
Economic uses
In Maryland, the Rose Hill Formation contained the Cresaptown Iron Sandstone.
Age
Relative age dating of the Clinton Group places it in the Lower Silurian period. It rests conformably atop the Tuscarora Formation and conformably below the Lower and Upper Silurian Lockport Group and Bloomsburg Formation.