Type designation:

Type area: The term “Salina” was first used by J. D. Dana (1863) in the combination Salina Period, during which time the Guelph limestones and marls and limestones and salt of the so-called Saliferous Epoch were said to be deposited in central New York (Shaver, 1970; Droste and Shaver, 1986).

History of usage:

Restriction: The Salina once included rocks assigned to the Onondaga Salt (Saliferous) Group (Dana, 1880, p. 232-233), but after long evolution of the term in New York, the name "Salina" became restricted to Silurian rocks and also synonymous with most of the Cayugan Series, that is, with the Upper Silurian Series of other common North American terminology using a tripartite division of the Silurian System (Droste and Shaver, 1986).

Usage in Appalachian and Michigan Basins: The name “Salina” has been used traditionally in both the Appalachian and Michigan Basins (Rickard, 1969; Mesolella, 1978; Landes, 1945; Ells, 1962; and Janssens, 1977), variably as a formation or a group. In the latter basin the Salina Group reaches thickness greater than 2,500 ft (762 m) and consists dominantly of alternating carbonate rocks and salts (Droste and Shaver, 1986). Southward the Salina lacks salts, becomes thinner (both depositionally and erosionally), and extends into a roughly wedge-shaped unit ranging in thickness from 500 ft (152 m) in northeastern Indiana to as little as 50 ft (15 m) in central Indiana (Droste and Shaver, 1986).

Extension: It was to part of this wedge that Pinsak and Shaver (1964, p. 47) first applied the name "Salina Formation" in Indiana, namely, to that part that lies buried north of the barrierlike Silurian feature in northern Indiana called the Fort Wayne Bank and to that outcropping part that had long been known as the Kokomo and Kenneth Limestones (Droste and Shaver, 1986). After convincing evidence of a nearly complete facies relationship between typical Salina rocks of Michigan and reef-bearing rocks southward had been produced, Droste and Shaver (1982) extended the term "Salina," as a group, to the whole of the wedge described above (Droste and Shaver, 1986). (See precise limits defined in Droste and Shaver, 1982, fig. 5 [Droste and Shaver, 1986]).

Subsidiary units: The named subsidiary units of the group became the Pleasant Mills Formation (below, and including the Limberlost Dolomite, Waldron, and Louisville Members) and the Wabash Formation (above, and including the Mississinewa Shale Member and the Liston Creek, Kokomo, and Kenneth Limestone Members) (Droste and Shaver, 1986). The Salina Group, therefore, includes all the classically studied reef-bearing section in northern Indiana as well as the more basin-type Salina facies (Droste and Shaver, 1986).


The Salina Group, thus defined, includes a great variety of dominantly carbonate rocks, ranging from fine-grained shaly rocks to pure carbonate-mud rocks and to coarse-grained vuggy bioclastic and otherwise highly fossiliferous rocks including reef-framework rocks; also, from open-marine deeper water carbonate rocks to very shallow marine, ecologically restricted rocks (Droste and Shaver, 1986). Bedded evaporites are unknown, however (Droste and Shaver, 1986).

Environments of deposition tended to change cyclically (Droste and Shaver, 1977; Droste, Rexroad, and Shaver, 1980; Shaver and Sunderman, 1983); these changes are interpretable from the classically studied rock units and their boundaries (Droste and Shaver, 1986). The several articles on these units (see names above) record the great lithologic complexities of the Salina Group (Droste and Shaver, 1986).

The geographic boundaries of the group consist of an eroded edge in central eastern Indiana and of a defined vertical cutoff along the distal limits of the lowermost Salina unit (Limberlost) (Droste and Shaver, 1986). The cutoff extends northwestward from Shelby County and, farther on, northward to the northwesternmost counties (Droste and Shaver, 1986). Thickness along this cutoff ranges from about 50 ft (15 m) in Shelby County to 400 ft (122 m) in Newton and Lake Counties (Droste and Shaver, 1986).

Much of this thickness change is due to pre-Middle Devonian erosion, as the top of the Salina Group is everywhere coincident with the Silurian-Devonian unconformity, which increases in magnitude (and extent of Silurian truncation) southeastward (Droste and Shaver, 1986). The bottom of the Salina Group is everywhere conformable, with possible rare minor exception, with the underlying Salamonie Dolomite (Droste and Shaver, 1986). A part of this relationship is very likely time transgressive (Droste and Shaver, 1986). (See also Okla, 1976, for a thorough treatment of Salina rocks in Indiana [Droste and Shaver, 1986]).


Many isolated to systematic studies in Indiana have recorded, during the modern period of study of the Salina rocks defined here, dozens of occurrences of key index fossils whose reliabilities are firmly established in a sequential stratigraphy that takes account of the ecologic factors (Droste and Shaver, 1986). In addition, stratigraphic sense has been made of the hundreds of once hopelessly stratigraphically/ecologically confused species that were the objects of classic study (Shaver, 1974; Droste and Shaver, 1986).

Each of the main grous—pentamerid brachiopods, conodonts, and ostracods—as well as the rarer but significant fossils—graptolites, acritarchs, and the mollusk Megalomus canadensis—now has a consistent stratigraphic meaning (Droste and Shaver, 1986). Collectively they show that the Salina Group in Indiana ranges in age from late Wenlockian (middle or late Niagaran) into Pridolian (late Cayugan) (Droste and Shaver, 1986). Significantly, some of the same indicators are common between the classically studied reef-bearing section and the rocks classically correlated with the Salina of other states, that is, the Kokomo and Kenneth rocks (Droste and Shaver, 1986). The commonness of lower Salina rocks with upper Niagaran rocks has also been shown in the Appalachian Basin states (Rickard, 1975; Mesolella, 1978; Janssens, 1977; and Patchen and Smosna, 1975; Droste and Shaver, 1986).

The youngest Salina rocks of Indiana, probably eroded at the top, are older than the youngest Salina rocks of the Michigan and Appalachian Basins (Droste and Shaver, 1986). Southwestward the Salina has age equivalence with the middle and upper parts of the Bainbridge Group of the Illinois Basin, but there, too, the youngest Bainbridge rocks are probably younger than the youngest Salina of Indiana (Droste and Shaver, 1986).

Regional Indiana usage:

Illinois Basin Margin (COSUNA 12)
Supergroup: none
Group: Salina Group
Cincinnati Arch (COSUNA 13)
Supergroup: none
Group: Salina Group
Kankakee Arch (COSUNA 14)
Supergroup: none
Group: Salina Group
Michigan Basin (COSUNA 15)
Supergroup: none
Group: Salina Group

Misc/Abandoned Names:

Huntington Dolomite, Huntington Limestone, Huntington Lithofacies, Huntington Stone

Geologic Map Unit Designation:


Note: Hansen (1991, p. 52) in Suggestions to authors of the reports of the United States Geological Survey noted that letter symbols for map units are considered to be unique to each geologic map and that adjacent maps do not necessarily need to use the same symbols for the same map unit. Therefore, map unit abbreviations in the Indiana Geologic Names Information System should be regarded simply as recommendations.

COSUNA areas and regional terminology

Names for geologic units vary across Indiana. The Midwestern Basin and Arches Region COSUNA chart (Shaver, 1984) was developed to strategically document such variations in terminology. The geologic map (below left) is derived from this chart and provides an index to the five defined COSUNA regions in Indiana. The regions are generally based on regional bedrock outcrop patterns and major structural features in Indiana. (Click the maps below to view more detailed maps of COSUNA regions and major structural features in Indiana.)

COSUNA areas and numbers that approximate regional bedrock outcrop patterns and major structural featuers in Indiana.

Major tectonic features that affect bedrock geology in Indiana.

See also:

Bainbridge Group


Dana, J. D., 1863, Manual of geology, 1st ed.: Philadelphia, 798 p.

Dana, J. D., 1880, Manual of geology, 3d ed.: New York, Ivison, Blakeman, Taylor, and Co., Publishers, xiv + 911 p.

Droste, J. B., and Shaver, R. H., 1977, Synchronization of deposition–Silurian reef-bearing rocks on Wabash Platform with cyclic evaporites of Michigan Basin, in Fisher, J. H., ed., Reefs and evaporites–concepts and depositional models: American Association of Petroleum Geologists Studies in Geology 5, p. 93-109.

Droste, J. B., and Shaver, R. H., 1982, The Salina Group (Middle and Upper Silurian) of Indiana: Indiana Geological Survey Special Report 24, 41 p.

Droste, J. B., and Shaver, R. H., 1986, Salina Group, in Shaver, R. H., Ault, C. H., Burger, A. M., Carr, D. D., Droste, J. B., Eggert, D. L., Gray, H. H., Harper, Denver, Hasenmueller, N. R., Hasenmueller, W. A., Horowitz, A. S., Hutchison, H. C., Keith, B. D., Keller, S. J., Patton, J. B., Rexroad, C. B., and Wier, C. E., Compendium of Paleozoic rock-unit stratigraphy in Indiana–a revision: Indiana Geological Survey Bulletin 59, p. 133-135.

Droste, J. B., Rexroad, C. B., and Shaver, R. H., 1980, The Silurian System in Indiana and environs–a key to regional paleogeography and to reef and evaporite controversies [abs.]: Geological Society of America Abstracts with Programs, v. 12, p. 224.

Ells, G. D., 1962, Silurian rocks in the subsurface of southern Michigan, in Fisher, J. H., chm., Silurian rocks of the southern Lake Michigan area: Michigan Basin Geological Society Annual Field Conference 1962, p. 39-49.

Hansen, W. R., 1991, Suggestions to authors of the reports of the United States Geological Survey (7th ed.): Washington, D.C., U.S. Geological Survey, 289 p.

Janssens, Adriaan, 1977, Silurian rocks in the subsurface of northwestern Ohio: Ohio Geological Survey Report of Investigations 100, 96 p.

Landes, K. K., 1945, The Salina and Bass Islands rocks in the Michigan Basin: U.S. Geological Survey Oil and Gas Investigations (Preliminary) Map 40.

Mesolella, K. J., 1978, Paleogeography of some Silurian and Devonian reef trends, central Appalachian Basin: American Association of Petroleum Geologists Bulletin, v. 62, p. 1,607-1,644.

Okla, S. M., 1976, Subsurface stratigraphy and sedimentation of Middle and Upper Silurian rocks of northern Indiana: Bloomington, Indiana University, Ph.D. thesis, 153 p.

Patchen, D. G., and Smosna, R. A., 1975, Stratigraphy and petrology of Middle Silurian McKenzie Formation in West Virginia: American Association of Petroleum Geologists Bulletin 59, p. 2,266-2,287; West Virginia Geological and Economic Survey Reports Investigation 25, 22 p. (1976)

Pinsak, A. P., and Shaver, R. H., 1964, The Silurian formations of northern Indiana: Indiana Geological Survey Bulletin 32, 87 p.

Rickard, L. V., 1969, Stratigraphy of the Upper Silurian Salina Group, New York, Pennsylvania, Ohio, Ontario: New York State Museum and Science Service Geological Survey Map and Chart Ser. 12, 57 p.

Rickard, L. V., 1975, Correlation of the Silurian and Devonian rocks in New York State: New York State Museum and Science Service Geological Survey Map and Chart Ser. 24, 16 p.

Shaver, R. H., 1970, Salina Formation, in Shaver, R. H., Burger, A. M., Gates, G. R., Gray, H. H., Hutchison, H. C., Keller, S. J., Patton, J. B., Rexroad, C. B., Smith, N. M., Wayne, W. J., and Wier, C. E., Compendium of rock-unit stratigraphy in Indiana: Indiana Geological Survey Bulletin 43, p. 155-157.

Shaver, R. H., 1974, The Niagaran (Middle Silurian) macrofaunas of northern Indiana–review, appraisal, and inventory: Indiana Academy of Science Proceedings, v. 83, p. 301-315.

Shaver, R. H., and Sunderman, J. A., 1983, Silurian reef and interreef strata as responses to a cyclical succession of environments, southern Great Lakes area (Field Trip 12), in Shaver, R. H., and Sunderman, J. A., eds., Field trips in midwestern geology: Bloomington, Indiana, Geological Society of America, Indiana Geological Survey, and Indiana University Department of Geology, v. 1, p. 141-196.

Shaver, R. H., coordinator, 1984, Midwestern basin and arches region–correlation of stratigraphic units in North America (COSUNA): American Association of Petroleum Geologists Correlation Chart Series.

For additional information contact:

Nancy Hasenmueller (
Date last revised: December 9, 2013