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Mineral Resources > Online Spatial Data > Geology > by state > Pennsylvania Geology

Geologic units in Columbia county, Pennsylvania

Spechty Kopf Formation (Mississippian and Devonian) at surface, covers 1.0 % of this area

Spechty Kopf Formation - Light- to olive-gray, fine- to medium- grained, crossbedded sandstone, siltstone, and local polymictic diamictite, pebbly mudstone, and laminite; arranged in crude fining-upward cycles in some places; locally has grayish-red shale near top and conglomerate at base and in middle.

Lithology: sandstone; siltstone; mudstone; shale; conglomerate

Llewellyn Formation (Pennsylvanian) at surface, covers 1 % of this area

Llewellyn Formation - Gray, fine- to coarse-grained sandstone, siltstone, shale, conglomerate, and numerous anthracite coals in repetitive sequences.

Lithology: sandstone; siltstone; shale; conglomerate; coal

Keyser and Tonoloway Formations, undivided (Devonian and Silurian) at surface, covers 0.8 % of this area

Keyser and Tonoloway Formations, undivided - In descending order: Keyser Formation--medium-gray, crystalline to nodular, fossiliferous limestone; upper part laminated and mud-cracked; not present east of Harrisburg; passes into lower Coeymans, Rondout, and Decker Formations in the east. Tonoloway Formation--medium-gray, laminated, mud-cracked limestone containing some medium-dark- or olive-gray shale interbeds; lower part passes into Wills Creek Formation east and south; passes into Bossardville and Poxono Island beds in the east.

Lithology: limestone; shale

Trimmers Rock Formation (Devonian) at surface, covers 30 % of this area

Trimmers Rock Formation - Olive-gray siltstone and shale, characterized by graded bedding; marine fossils; some very fine grained sandstone in northeast; black shale of Harrell Formation at base in Susquehanna Valley.

Lithology: siltstone; shale; sandstone; black shale

Bloomsburg and Mifflintown Formations, undivided (Silurian) at surface, covers 2 % of this area

Bloomsburg and Mifflintown Formations, undivided - Includes, in descending order, the Bloomsburg Formation (Sb) and the Mifflintown Formation--interbedded dark-gray shale and medium-gray fossiliferous limestone; equivalent to "McKenzie" and "Rochester" of earlier workers; not present east of Harrisburg.

Lithology: shale; siltstone; sandstone; limestone; mudstone

Burgoon Sandstone (Mississippian) at surface, covers 0.1 % of this area

Burgoon Sandstone - Buff, medium-grained, crossbedded sandstone; includes shale and coal; in places, contains conglomerate at base; contains plant fossils; equivalent to Pocono Formation of Ridge and Valley province.

Lithology: sandstone; conglomerate; shale; coal

Sherman Creek Member of Catskill Formation (Devonian) at surface, covers 7 % of this area

Sherman Creek Member of Catskill Formation - Alternating grayish-red mudstone and siltstone in poorly defined fining-upward cycles, and minor intervals of gray sandstone; laterally equivalent to Berry Run, Sawmill Run, Packerton, and Long Run Members of eastern Pennsylvania.

Lithology: mudstone; siltstone; sandstone

Pocono Formation (Mississippian) at surface, covers 5 % of this area

Pocono Formation - Light-gray to buff or light-olive-gray, medium-grained, crossbedded sandstone and minor siltstone; commonly conglomeratic at base and in middle; medial conglomerate, where present, is used to divide into Mount Carbon and Beckville Members; equivalent to Burgoon Sandstone of Allegheny Plateau.

Lithology: sandstone; siltstone; conglomerate

Pottsville Formation (Pennsylvanian) at surface, covers 2 % of this area

Pottsville Formation - Predominantly gray sandstone and conglomerate; also contains thin beds of shale, claystone, limestone, and coal; includes Olean and Sharon conglomerates of northwestern Pennsylvania; thin marine limestones present in Beaver, Lawrence, and Mercer Counties; minable coals and commercially valuable high-alumina clays present locally.

Lithology: sandstone; conglomerate; shale; siltstone; claystone; limestone; coal

Wills Creek Formation (Silurian) at surface, covers 2 % of this area

Wills Creek Formation - Variegated gray, grayish-red, yellowish-gray and greenish-gray, interbedded calcareous shale, siltstone, shaly limestone, and dolomite; passes into Bloomsburg Formation in the southeast; not present east of Harrisburg.

Lithology: shale; siltstone; limestone; dolostone (dolomite)

Onondaga and Old Port Formations, undivided (Devonian) at surface, covers 0.4 % of this area

Onondaga and Old Port Formations, undivided - Includes, in descending order, the Onondaga Formation (Don), Ridgeley Member of Old Port Formation (Dor), and Shriver, Mandata, Corriganville, and New Creek Members of Old Port Formation, undivided (Dosn).

Lithology: shale; sandstone; limestone; chert; shale; siltstone; bentonite

Catskill Formation (Devonian) at surface, covers 8 % of this area

Catskill Formation - Grayish-red sandstone, siltstone, shale, and mudstone; locally conglomeratic; contains gray sandstone in upper part; lithologies arranged in fining-upward cycles; equivalent to the Hampshire Formation south of Pennsylvania.

Lithology: sandstone; siltstone; shale; mudstone; conglomerate

Duncannon Member of Catskill Formation (Devonian) at surface, covers 1 % of this area

Duncannon Member of Catskill Formation - Grayish-red sandstone, siltstone, and mudstone in fining-upward cycles; conglomerate occurs at base of some cycles.

Lithology: sandstone; siltstone; mudstone; conglomerate

Irish Valley Member of Catskill Formation (Devonian) at surface, covers 10 % of this area

Irish Valley Member of Catskill Formation - Nonmarine, grayish-red siltstone and mudstone, and gray and grayish-red sandstone interbedded with minor, thin, light-olive-gray marine siltstone; arranged in fining-upward cycles. Lower part of member has conglomeratic sandstones.

Lithology: siltstone; mudstone; sandstone; conglomerate

Clinton Group (Silurian) at surface, covers 1 % of this area

Clinton Group - Predominantly Rose Hill Formation--light-olive-gray to brownish-gray, fossiliferous shale; locally, limestone occurs near top; includes dark-reddish-gray, very fine to coarse-grained, ferruginous sandstone; east of Harrisburg, equivalent to Lizard Creek Member of Shawangunk Formation. Above Rose Hill is Keefer Formation--light- to dark-gray, fossiliferous sandstone, hematitic, oolitic sandstone, and shale; not recognized east of Harrisburg.

Lithology: shale; sandstone; limestone

Huntley Mountain Formation (Mississippian and Devonian) at surface, covers 0.6 % of this area

Huntley Mountain Formation - Greenish-gray and light-olive-gray, flaggy, fine-grained sandstone, siltstone, and a few red shale interbeds; includes lower "Pocono" plus "Oswayo" of earlier workers. Forms transition between Catskill Formation and Burgoon Sandstone.

Lithology: sandstone; siltstone; shale

Hamilton Group (Devonian) at surface, covers 10 % of this area

Hamilton Group - Includes, in descending order, the Mahantango (Dmh) and Marcellus (Dmr) Formations.

Lithology: black shale; shale; siltstone; limestone; sandstone; bentonite

Mauch Chunk Formation (Mississippian) at surface, covers 7 % of this area

Mauch Chunk Formation - Grayish-red shale, siltstone, sandstone, and some conglomerate; some local nonred zones. Includes Loyalhanna Member (crossbedded, sandy limestone) at base in south-central and southwestern Pennsylvania; also includes Greenbrier Limestone Member, and Wymps Gap and Deer Valley Limestones, which are tongues of the Greenbrier. Along Allegheny Front from Blair County to Sullivan County, Loyalhanna Member is greenish-gray, calcareous, crossbedded sandstone.

Lithology: shale; siltstone; sandstone; conglomerate; limestone

Buddys Run Member of Catskill Formation (Devonian) at surface, covers 10 % of this area

Buddys Run Member of Catskill Formation - Grayish-red and brownish-gray siltstone, mudstone, and sandstone; some gray and dusky-yellow sandstone and siltstone; laterally equivalent to Duncannon, Clarks Ferry, and Sherman Creek Members.

Lithology: siltstone; sandstone; mudstone