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

Geologic units in Lebanon county, Pennsylvania

Clinton Group (Silurian) at surface, covers 0.5 % 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

Irish Valley Member of Catskill Formation (Devonian) at surface, covers 0.8 % 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

Diabase (Jurassic) at surface, covers 3 % of this area

Diabase - Medium- to coarse-grained, quartz-normative tholeiite; composed of labradorite and various pyroxenes; occurs as dikes, sheets, and a few small flows. Includes the dark-gray York Haven Diabase (high titanium oxide) and the slightly younger Rossville Diabase (low titanium oxide). In chilled margins, the Rossville is distinguished from the York Haven by its lighter gray color and distinctive, sparse, centimeter-sized calcic-plagioclase phenocrysts.

Lithology: diabase

Martinsburg Formation (Ordovician) at surface, covers 2 % of this area

Martinsburg Formation - Gray to dark-gray, buff-weathering shale.

Lithology: shale

Hammer Creek conglomerate (Triassic) at surface, covers 3 % of this area

Hammer Creek conglomerate - Cobble and pebble quartz conglomerate interbedded with red sandstone.

Lithology: conglomerate; sandstone

Hamilton Group (Devonian) at surface, covers 1 % of this area

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

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

Clarks Ferry Member of Catskill Formation (Devonian) at surface, covers 0.4 % of this area

Clarks Ferry Member of Catskill Formation - Gray to yellowish-gray sandstone, siltstone, and conglomerate.

Lithology: sandstone; siltstone; conglomerate

Jonestown Volcanic Suite (Ordovician) at surface, covers 1.0 % of this area

Jonestown Volcanic Suite - Andesite extrusives and dark-greenish-gray metadiabase. Metadiabase weathers medium gray to brown, forming rounded cobbles and boulders.

Lithology: andesite; mafic metavolcanic rock

Mauch Chunk Formation (Mississippian) at surface, covers 2 % 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

Hershey and Myerstown Formations, undivided (Ordovician) at surface, covers 2 % of this area

Hershey and Myerstown Formations, undivided - In descending order: Hershey--dark-gray to black, thin-bedded, argillaceous limestone; Myerstown--medium- to dark-gray, platy, medium-crystalline limestone; carbonaceous at base.

Lithology: limestone

Hammer Creek Formation (Triassic) at surface, covers 7 % of this area

Hammer Creek Formation - Gray and pale red, fine- to coarse-grained quartzose sandstone, siltstone, and mudstone.

Lithology: sandstone; siltstone; mudstone

Richland Formation (Cambrian) at surface, covers 5 % of this area

Richland Formation - Gray dolomite, in part oolitic, interbedded with medium-gray limestone and dark-gray oolitic chert.

Lithology: dolostone (dolomite); limestone; chert

Hornblende gneiss (Precambrian) at surface, covers 0.6 % of this area

Hornblende gneiss - Dark, medium grained; includes some rocks of probable sedimentary origin.

Lithology: mafic gneiss; paragneiss

Snitz Creek Formation (Cambrian) at surface, covers 3 % of this area

Snitz Creek Formation - Thick-bedded, medium- to coarsely crystalline dolomite, in part oolitic, containing laminated limestone and sandstone interbeds.

Lithology: dolostone (dolomite); limestone; sandstone

Duncannon Member of Catskill Formation (Devonian) at surface, covers 0.4 % 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

Felsic to mafic gneiss (Precambrian) at surface, covers 0.7 % of this area

Felsic to mafic gneiss - Light, medium grained; predominantly quartz and feldspar of igneous origin.

Lithology: felsic gneiss; mafic gneiss; orthogneiss

Limestone of Hamburg sequence (Ordovician) at surface, covers 1 % of this area

Limestone of Hamburg sequence - Conspicuous limestone.

Lithology: limestone

Tuscarora Formation (Silurian) at surface, covers 0.4 % of this area

Tuscarora Formation - Light- to medium-gray quartzite and quartzitic sandstone and minor interbedded shale and siltstone, locally conglomeratic in lower part; includes (to the northwest) interbedded red and non-red sandstone (Castanea Member) at top; east of Harrisburg, equivalent to Minsi and Weiders Members of Shawangunk Formation.

Lithology: quartzite; sandstone; shale; siltstone; conglomerate

Hardyston Formation (Cambrian) at surface, covers 0.4 % of this area

Hardyston Formation - Typically light-gray, fine- to medium-grained quartzite, and feldspathic sandstone; color ranges from nearly white to dark gray; massive bedded; Scolithus present in upper part; quartz-pebble conglomerate occurs at base.

Lithology: quartzite; sandstone; conglomerate

Leithsville Formation (Cambrian) at surface, covers 0.4 % of this area

Leithsville Formation - Medium- to dark-gray, crystalline dolomite, light-olive-gray in places, weathering to light gray and yellowish brown; massive bedded; oolitic; pink to gray, mottled chert and dark-gray chert; thin shale and dolomitic shale interbeds; scattered sand grains; upper part is very shaly.

Lithology: dolostone (dolomite); shale; chert; sand

Bloomsburg Formation (Silurian) at surface, covers 1 % of this area

Bloomsburg Formation - Grayish-red siltstone, shale, and sandstone arranged in fining-upward cycles.

Lithology: siltstone; shale; sandstone

Limestone fanglomerate (Triassic) at surface, covers 0.3 % of this area

Limestone fanglomerate - Yellowish-gray to medium-gray, angular limestone and dolomite pebbles, cobbles, and fragments set in a red, very fine grained quartz matrix; a few shale-clast interbeds.

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

Buffalo Springs Formation (Cambrian) at surface, covers 4 % of this area

Buffalo Springs Formation - Light-gray to pinkish-gray, finely to coarsely crystalline limestone and interbedded dolomite; numerous siliceous and clayey laminae; stromatolitic limestone beds near top; some thin sandy beds.

Lithology: limestone; dolostone (dolomite); sandstone

Graphitic felsic gneiss (Precambrian) at surface, covers < 0.1 % of this area

Graphitic felsic gneiss - Includes Pickering Gneiss and small areas of marble; dominantly quartz and feldspar with varying amounts of graphite and various metamorphic minerals; medium grained, light to dark gray and greenish gray; sedimentary origin.

Lithology: gneiss; marble; paragneiss

Millbach and Schaefferstown Formations, undivided (Cambrian) at surface, covers 3 % of this area

Millbach and Schaefferstown Formations, undivided - Includes, in descending order, the Millbach Formation (CAm), and the Schaefferstown Formation--gray limestone containing siliceous and argillaceous laminae; thin bedded.

Lithology: limestone; dolostone (dolomite); shale

Onondaga Formation through Poxono Island Formation, undivided (Devonian and Silurian) at surface, covers 0.2 % of this area

Onondaga Formation through Poxono Island Formation, undivided - In descending order: Onondaga Formation--gray calcareous, sandy shale; Ridgeley Formation--brown sandstone; Rondout Formation--gray interbedded limestone, dolomite, and shale; Decker Formation--gray calcareous sandstone, and Andreas Red Beds at top; Bossardville Limestone--gray, mud-cracked shaly limestone; Poxono Island Formation--olive-gray, calcareous and dolomitic shale, siltstone, and sandstone.

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

Gettysburg Formation (Triassic) at surface, covers 1 % of this area

Gettysburg Formation - Reddish-brown to maroon, silty mudstone and shale containing thin red sandstone interbeds; several thin beds of impure limestone.

Lithology: mudstone; silt; shale; sandstone; limestone

Ontelaunee Formation (Ordovician) at surface, covers 2 % of this area

Ontelaunee Formation - Light- to dark-gray, very finely to medium-crystalline dolomite containing interbeds of light-gray limestone; interbedded nodular, dark-gray chert at base.

Lithology: dolostone (dolomite); limestone; chert

Rickenbach Formation (Ordovician) at surface, covers 1 % of this area

Rickenbach Formation - Gray, very finely to coarsely crystalline, laminated dolomite; dark-gray chert in irregular beds, stringers, and nodules; bands of quartz sand grains in lower half.

Lithology: dolostone (dolomite); chert

Graywacke of Hamburg sequence (Ordovician) at surface, covers 4 % of this area

Graywacke of Hamburg sequence - Predominantly graywacke.

Lithology: graywacke

Pottsville Formation (Pennsylvanian) at surface, covers 1 % 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

Spechty Kopf Formation (Mississippian and Devonian) at surface, covers 0.4 % 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

Epler Formation (Ordovician) at surface, covers 4 % of this area

Epler Formation - Very finely crystalline, light-gray limestone interbedded with gray dolomite; coarsely crystalline limestone lenses present.

Lithology: limestone; dolostone (dolomite)

Stonehenge Formation (Ordovician) at surface, covers 4 % of this area

Stonehenge Formation - Stromatolitic, fine-grained limestone; includes coarser grained and conglomeratic, siliceous, laminated Stoufferstown Formation at base in most of Cumberland Valley.

Lithology: limestone

Annville Formation (Ordovician) at surface, covers 0.7 % of this area

Annville Formation - Light-gray, massive, high-calcium limestone; mottled at base.

Lithology: limestone

New Oxford Formation (Triassic) at surface, covers < 0.1 % of this area

New Oxford Formation - Light-gray to buff, commonly arkosic sandstone interbedded with red shale, mudstone, and fine-grained sandstone

Lithology: arkose; shale; mudstone; sandstone

Shawangunk Formation (Silurian) at surface, covers 0.5 % of this area

Shawangunk Formation - Light- to dark-gray, fine- to very coarse grained sandstone and conglomerate containing thin shale interbeds. Includes four members, in descending order: Tammany--conglomerate and sandstone; Lizard Creek--sandstone and red or green shale; Minsi--sandstone and conglomerate; Weiders--conglomerate. Tammany and Lizard Creek Members together are approximately equivalent to Clinton Group to the west; Minsi and Weiders Members together are equivalent to Tuscarora Formation to the west.

Lithology: sandstone; conglomerate; shale

Trimmers Rock Formation (Devonian) at surface, covers 1 % 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

Sherman Creek Member of Catskill Formation (Devonian) at surface, covers 2 % 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

Shale and graywacke of Hamburg sequence (Ordovician) at surface, covers 1 % of this area

Shale and graywacke of Hamburg sequence - Shale containing zones of conspicuous graywacke.

Lithology: shale; graywacke

Hamburg sequence rocks (Ordovician) at surface, covers 30 % of this area

Hamburg sequence rocks - Predominantly greenish gray, gray, purple, and maroon shale, siltstone, and graywacke; includes some wildflysch having Martinsburg matrix.

Lithology: shale; siltstone; graywacke; conglomerate

Pocono Formation (Mississippian) at surface, covers 0.6 % 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