The Carbondale Group is a Middle Pennsylvanian aged unit found in the Illinois Basin. This geologic unit is made up of

siliciclastic Siliciclastic (or ''siliclastic'') rocks are clastic noncarbonate sedimentary rocks that are composed primarily of silicate minerals, such as quartz or clay minerals. Siliciclasic rock types include mudrock, sandstone Sandstone is a clastic ...

rock and

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when dea ...

beds.

Description

The Carbondale is made up of mostly siliciclastic lithology. There are several coal beds as well as well as some

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

member units. Some coal beds are commercially viable and a number of mines extract coal from this geologic unit.

Stratigraphy

Dugger formation

The Dugger formation is at the top and therefore the youngest of the group. This formation contains more sandstone and serves as an aquifer for domestic use.

Petersburg Formation

The Petersburg formation also contains sandstone members that are used as aquifers.

Linton Formation

The Linton Formation is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...

. It is the lower formation in the Carbondale Group, and includes six named members, "which, in ascending order, are the Seelyville Coal, Coxville Sandstone, Colchester Coal, Mecca Quarry Shale, Velpen Limestone, and Survant Coal Members, and unnamed units of sandstone, shale, and clay". It preserves

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...

dating back to the

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

. The Linton Formation was first named on a United States Geological Survey coal investigations map in 1950. The type locality is along the tributaries of Lattas Creek, approximately 4 miles north of Linton,

Greene County, Indiana Greene County is a county in the U.S. state of Indiana. As of 2010, the population was 33,165. The county seat is Bloomfield. The county was determined by the US Census Bureau to include the mean center of U.S. population in 1930. History Gree ...

References

{{Chronostratigraphy of Illinois Carboniferous Illinois Carboniferous Indiana