Stratigraphically, the Salina is placed in the
Late Silurian age and is the lower member of the Cayugan
Series. It overlies predominantly the
Lockport; in parts central to northeast Pennsylvania it overlies the
Bloomsburg Formation. It also underlies the
Helderberg Group.
Appalachian & Michigan Basins Being a thick formation, the Salina has subunits, as well as letter designations for the different formations. The letters originate at the base (oldest) with the A unit to the stratigraphic top H unit (youngest) made up of
Anhydrite. During an extensive study in the state of
Michigan, each unit was mapped. Unit A consists of dolomite and shaly dolomite, and is the bottom of the Vernon. Where the formation thickens, there may also be one or two large salt beds within the unit. Anhydrite can be found throughout this unit. Due to unit A having two salt or anhydrite beds, it is often divided into the A1 and A2, with A1 being the basal unit. Unit B is another salt unit and marks the Middle Vernon. The percentage of salt can range from 90% to 100%. Thin dolomite beds run through this unit. In comparison, Unit C marks the top of the
Vernon Formation. It is a shaly dolomite; however, it can range from pure shale to pure dolomite beds within the unit. Anhydrite can be prevalent within this unit as well. Unit D, the bottom of the Syracuse formation, is almost pure salt. Some dolomite may also occur within this unit. It is the thinnest unit of the Salina, and is not always present. Unit E consists of shale, but can include dolomitic shale and dolomite. Anhydrite may also be present within this unit and is also part of the Syracuse. Unit F is the youngest and largest salt in the group, also known as the
Syracuse Formation. Where thicker, the F has beds of salt separated by rock grading from shale to dolomite, often with anhydrite present especially in the shale. Unit G is the
Camillus, which consists of dolomite and anhydrite while unit H is known as the
Bertie Formation. In the Michigan Basin, the Bertie is pinched out; the
Bass Islands Formation makes up the upper most Salina.
Cincinnati Arch & Findlay Arch In this region the Salina is made of primarily dolostone and shale. The B - G groups are undifferentiated and have localized occurrences of salt and anhydrite general just called Salina formation. Below the Undifferentiated Salina is the Tymochtee Formation. This can be light to dark gray dolomite. Moving west it becomes more shaley to the point that it maybe considered dolomitic shale. It contains traces of anhydrite and gypsum nodules. Locally fowling water wells with a sulphureous (rotten egg) odor.
Illinois Basin Wabash Formation Wabash Formation made up of the Liston Creek Member, Kenneth Limestone Member, Kokomo Limestone Member and the Mississinewa Shale member.
Pleasant Mills Formation The
Pleasant Mills Formation is made up of the Louisville Equivalent Member and Waldon Equivalent Member and Limberlost Dolomite Member. The Pleasant Mills Formation is equivalent to the entire "A Unit" in the Appalachian Basin. == Economic Resources ==