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Mineral Resources > Online Spatial Data > Geology > by state > South Dakota Geology

Geologic units in Lawrence county, South Dakota

[Additional scientific data in this geographic area]

Spearfish Formation (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers 5 % of this area

Red sandy shale, siltstone, sandstone, and minor limestone. Interbedded with abundant gypsum. Thickness 328-559 ft (100-170 m).

Lithology: shale; siltstone; sandstone; evaporite; limestone

Metabasalt (Archean(?) Proterozoic | Paleoproterozoic) at surface, covers < 0.1 % of this area

Dark-green amphibolite and amphibolite schist. Thickness of individual flows 50-200 ft (15-61 m).

Lithology: amphibolite; schist

Latitic Intrusive Rocks (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene) at surface, covers 1 % of this area

Dark-gray to greenish-gray laccoliths and sills of latite, latitic andesite, and quartz latite. Contains phenocrysts of andesine, oligoclase, biotite, hornblend, and sphene in a finely crystalline andesine-biotite-quartz groundmass.

Lithology: latite; andesite

Metamorphosed Tuffaceous Shale (Proterozoic | Paleoproterozoic) at surface, covers < 0.1 % of this area

Light-gray to light-tan, muscovite schist and muscovite phylite. Thickness approximately 1,000-3,000 ft (305-914 m).

Lithology: schist; phyllite

Metamorphosed Black Shale (Proterozoic | Paleoproterozoic) at surface, covers 0.3 % of this area

Dark-gray biotite schist, biotite-muscovite schist, pyritic biotite schist, and local massive chert beds. Thickness approximately 2000-4000 ft (610-1,219 m).

Lithology: schist; chert

Metamorphosed Shale (Proterozoic | Paleoproterozoic) at surface, covers 4 % of this area

Gray to dark-gray phylite, slate, and mica schist. Estimated thickness at least 5,000 ft (1,524 m).

Lithology: phyllite; slate; schist

Madison Group (Phanerozoic | Paleozoic | Devonian Carboniferous Mississippian) at surface, covers 20 % of this area

Includes: Pahasapa Limestone (Mississippian)-White, light-gray to tan, fine- to medium-crystalline limestone and dolomite containing brown to gray chert. Solution features including collapse breccia, sinkholes, and caves are prevalent. Thickness 300-630 ft (91-192 m). Englewood Formation (Mississippian to Dovonian)- Pink, lavender to light-gray, thin- to medium-bedded, finely crystalline, argillaceous, dolomitic limestone. Thickness 30-63 ft (9-19 m).

Lithology: limestone; dolostone (dolomite); chert

Metagraywacke Unit 3 (Proterozoic | Paleoproterozoic) at surface, covers < 0.1 % of this area

Upper Xgw- Light- to dark-gray, silceous mica schist and impure quartzite.

Lithology: schist; quartzite

Phonolitic Intrusive Rocks (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene) at surface, covers 1 % of this area

Gray to greenish-gray sills, laccoliths, and small stocks of phonolite, trachyphonolite, and trachyandesite. Contains phenocrysts of andesine, feldspathoids, aegirine-augite, biotite, and sphene in a finely crystalline plagioclase-biotote-feldsphoid groundmass.

Lithology: phonolite; trachyte

Minnekahta Limestone and Opeche Shale (Phanerozoic | Paleozoic | Permian) at surface, covers < 0.1 % of this area

MINNEKAHTA LIMESTONE AND OPECHE SHALE. MINNEKAHTA LIMESTONE--Gray slabby hard limestone. Locally is a member of the Goose Egg Formation. OPECHE SHALE--Red soft sandy shale. Locally is a member of the Goose Egg Formation.

Lithology: limestone; shale

Pahasapa and Englewood Limestones (Phanerozoic | Paleozoic | Devonian-Late Carboniferous Mississippian-Early) at surface, covers < 0.1 % of this area

PAHASAPA AND ENGLEWOOD LIMESTONES. PAHASAPA LIMESTONE--Gray massive dolomitic limestone. ENGLEWOOD LIMESTONE--Pink slabby dolomitic limestone.

Lithology: limestone

Mowry Shale, Newcastle Sandstone, and Skull Creek Shale (Phanerozoic | Mesozoic | Cretaceous-Early ) at surface, covers 4 % of this area

Mowry Shale- Black to gray, siliceous, fissile shale and siltstone containing bentonite layers, and sparse sandstone dikes and sills. Thickness 125-250 ft (38-76 m). Newcastle Sandstone- Gray, light-brown to yellow, discontinuously distributed siltstone, claystone, sandy shale, and fine-grained sandstone. Thickness up to 290 ft (88 m). Skull Creek Shale- Dark-gray to blueish-gray shale containing ferruginous, and carbonate concretions. Thickness 150-275 ft (46-84 m).

Lithology: shale; siltstone; sandstone; claystone

Metabasalt (Proterozoic | Paleoproterozoic) at surface, covers 0.1 % of this area

Alkalic basalt, greenstone, and actinolite schist. Includes metamorphosed volcanoclastic rocks and iron-rich schist.

Lithology: basalt; greenschist

Colluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.2 % of this area

Clay to boulder-size clasts forming rubble residuum and talus. Thickness up to 30 ft (9m).

Lithology: clay or mud; silt; sand; gravel

Terrace Deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers 3 % of this area

Clay to boulder-size clasts deposited as pediments, paleochannels, and terrace fills of former flood plains. Thickness up to 75 ft (23m).

Lithology: clay or mud; silt; sand; gravel

Minnekahta Limestone and Opeche Shale (Phanerozoic | Paleozoic | Permian) at surface, covers 5 % of this area

Minnekahta Limestone-Purple to gray, finely crystalline, thin- to medium-bedded limestone with varying amounts of red shale. Thickness 30-50 ft (9-15 m). Opeche Shale- Red siltstone, argillaceous sandstone and shale interbedded with caliche layers. Thickness 85-130 ft (26-40 m).

Lithology: siltstone; sandstone; shale; limestone

Older Metasedimentary Rocks (Archean ) at surface, covers < 0.1 % of this area

Gray phyillite, mica schist, and biotite-plagioclase schist. Total thickness unknown; approximately 500 ft (152 m) exposed.

Lithology: phyllite; schist

Greenhorn Formation (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers < 0.1 % of this area

Gray shale, mudstone, marl, calcarenite, and shaley limestone grading upward into light-gray to tan, alternating marl and thin-bedded, fossiliferous limestone. Thickness 225-315 ft (69-96 m).

Lithology: shale; mudstone; limestone

Metamorphosed Carbonaceous Shale (Proterozoic | Paleoproterozoic) at surface, covers 1.0 % of this area

Dark-gray to gray, siliceous biotite phyllite and schist. Thickness greater than 2,500 ft (762m).

Lithology: phyllite; schist

Metagraywacke (Proterozoic | Paleoproterozoic) at surface, covers 4 % of this area

Light- to dark-gray, silceous mica schist and impure quartzite. Differentiated where possible into three primary tongues or lenses. (Xgw1, Xgw2, and Xgw3) Thickness from 1,000 ft to over 5,000 ft (305-1,524 m).

Lithology: schist; quartzite

Metaconglomerate (Proterozoic | Paleoproterozoic) at surface, covers 0.5 % of this area

Tan to light-gray, conglomeratic siliceous schist, feldspathic schist, and minor marble. Thickness locally over 6,000 ft (1,829 m).

Lithology: schist; marble

Morrison Formation, Unkpapa Sandstone, Sundance Formation, and Gypsum Spring Formation (Phanerozoic | Mesozoic | Jurassic-Middle Jurassic-Late) at surface, covers 2 % of this area

Morrison Formation (Late Jurassic)- Light-gray to green and variegatedred, brown, yellow, or lavender, silceous claystone, shale, and siltstone containing interbedded sandstone and fresh-water limestone lenses. Thickness up to 150 ft (46 m). Unkpapa Sandstone (Late Jurassic)- White, massive to thin-bedded, fine-grained, argillaceous sandstone. May be variegated to banded red, yellow, brown, or lavender. Thickness up to 267 ft (81 m). Sundance Formation (Late to Middle Jurassic)- Greenish-gray, yellow, tan, red to orange, and white, variegated, interbedded, fine- to coarse-grained sandstone, siltstone, clay, and limestone. Thickness 250-350 ft (76-107 m). Gypsum Springs Formation (Middle Jusassic)- Massive white gypsum and minor maroon siltstone and shale. Thickness up to 40 ft (12 m).

Lithology: sandstone; siltstone; claystone; clay or mud; shale; limestone; evaporite

Rhyolitic Intrusive Rocks (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene) at surface, covers 2 % of this area

Light-tan to light-gray stocks and small laccoliths of rhyolite. Contains phenocrysts of oligoclase, quartz, and biotite in a finely crystalline orthoclase or sanidine-quartz groundmass.

Lithology: rhyolite

White River Group (Phanerozoic | Cenozoic | Tertiary | Eocene Oligocene) at surface, covers 1 % of this area

Includes: Brule Formation (Oligocene)- White, pink, light-green, and light-brown, massive to thin-bedded, bentonitic claystone, tuffaceous siltstone, and well-bedded, calcareous, tuffaceous quartz sandstone. Thickness up to 150 ft (46 m). Chadron Formation (Eocene)- Upper beds are gray, light-brown to maroon bentonite, claystone, siltstone tuffaceous fine-grained sandstone, and local, silicified carbonate lenses. Basal portion consists of poorly cemented, white, coarse-grained arkose and conglomerate. Thickness up to 160 ft (49 m). Chamberlain Pass Formation (Eocene)- Pale olive to pale red, mottled mudstone containing white, cross-bedded channel sandstone with basal conglomerate. Thickness up to 32 ft (10 m). Slim Buttes Formation (Eocene)- White, grayish- to yellowish-orange,pale-red to pink siltstone, clayey siltstone, bentonitic claystone,medium- to fine-grained sandstone, and conglomerate. Thickness up to 48 ft (15 m).

Lithology: claystone; siltstone; clay or mud; sandstone; mudstone; conglomerate

Alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 5 % of this area

Clay to boulder-size clasts with locally abundant organic material. Thickness up to 75 ft (23m).

Lithology: clay or mud; silt; sand; gravel

Minnelusa Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers 11 % of this area

Variegated, yellow to red, gray to brown, pink to purple, and black, interbedded sandstone, siltstone, shale, limestone, dolomite, calcarenite, chert and brecciated beds. Thickness 394-1,175 ft (120-358 m).

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

Metamorphosed Siltstone (Proterozoic | Paleoproterozoic) at surface, covers 3 % of this area

Medium-gray to dark-greenish-gray phyllite, slate, and biotite schist containing minor chert and amphibolite. Locally intruded by thin metagabbro sills. Thickness 1,000-3,000 ft (305-914 m).

Lithology: phyllite; slate; schist; chert; amphibolite; gabbro

Iron-Formation (Proterozoic | Paleoproterozoic) at surface, covers 0.1 % of this area

Banded, dark-green, reddish-brown, and white iron-formation, ferruginous chert, and minor mica schist. Includes three or more ages of oxide-, carbonate-, silicate-, and sulifide-facies iron-formation and interbedded tuffaceous rocks. Thickness 20-500 ft (6-152 m).

Lithology: iron formation; chert; schist

Metaconglomerate and Metaquartzite (Proterozoic | Paleoproterozoic) at surface, covers 1 % of this area

Light-gray to gray, conglomeratic and feldspathic schist, biotite schist, taconite, and phyllite. Individual conglomerate and fanglomerate tongues from 100-500 ft (30-152 m) thick. Total thickness over 10,000 ft (3,048 m).

Lithology: schist; iron formation; phyllite

Belle Fourche Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers 1 % of this area

Dark-gray to black bentonitic shale containing minor limestone lenses, bentonite layers, fossiliferous calcarenite, and large, ferruginous, carbonate concretions. Thickness 150-350 ft (46-107 m).

Lithology: shale; limestone; clay or mud

Inyan Kara Group (Phanerozoic | Mesozoic | Cretaceous-Early ) at surface, covers 4 % of this area

Includes: Fall River Formation- Variegated brown, red, gray to purple, calcareous, well-sorted, fine-grained sandstone, siltstone, and shale containing mica flakes. Thickness 100-200 ft (30-61 m). Lakota Formation- Yellow, brown, red-brown, gray to black silty shale, pebble conglomerate, and massive to thin-bedded, cross-bedded sandstone. Locally interbedded with fresh-water limestone and bituminous coal beds. Thickness 35-500 ft (11-152 m).

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

Pegmatite (Archean(?) Proterozoic | Paleoproterozoic) at surface, covers < 0.1 % of this area

Light-tan to pink pegmatite

Lithology: granite

Metamorphosed Dolomite (Proterozoic | Paleoproterozoic) at surface, covers 0.2 % of this area

Light-gray to light-tan marble, phyllite, and calcareous phyllite. Thickness 60-300 ft (18-91 m).

Lithology: marble; phyllite

Granite (Archean ) at surface, covers 0.1 % of this area

Pink and gray, strongly foliated, medium- to coarse-crystalline, locally pegmatitic, biotite-muscovite granite and gneissic granite.

Lithology: granite

Pahasapa Limestone, Englewood Formation, Whitewood Limestone, Winnipeg Formation, and Deadwood Formation (Phanerozoic | Paleozoic | Cambrian Ordovician(?) Silurian(?) Devonian(?) Carboniferous Mississippian) at surface, covers 2 % of this area

Note: see individual descriptions

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

Gravel, pediment, and fan deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers < 0.1 % of this area

GRAVEL, PEDIMENT, AND FAN DEPOSITS--Mostly locally derived clasts. Includes some glacial deposits along east flank of Wind River Range. Locally includes some Tertiary gravels.

Lithology: unconsolidated deposit

Minnelusa Formation (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Early Pennsylvanian-Middle(?) Pennsylvanian-Late(?) Permian) at surface, covers < 0.1 % of this area

MINNELUSA FORMATION--Buff and red limy sandstone; some thin limestone beds, solution breccias, and gypsum.

Lithology: sandstone; limestone; evaporite

Metamorphosed Carbonaceous Shale (Proterozoic | Paleoproterozoic) at surface, covers 0.3 % of this area

Dark-gray to gray, siliceous biotite phyllite, calcareous biotite phyllite, and schist. Minimum thickness 1,500 ft (457 m).

Lithology: phyllite; schist

Metaquartzite (Proterozoic | Paleoproterozoic) at surface, covers 2 % of this area

Light-tan quartzite, siliceous schist, and minor chert. Thickness 800-5,000 ft (244-1,524 m).

Lithology: quartzite; schist; chert

Spearfish Formation (Phanerozoic | Paleozoic Mesozoic | Permian Triassic-Early(?) Triassic-Middle(?) Triassic-Late) at surface, covers < 0.1 % of this area

SPEARFISH FORMATION--Red shale, red siltstone, and white gypsum beds; gypsum beds especially abundant near base.

Lithology: mudstone; evaporite

Whitewood Limestone, Winnipeg Formation, and Deadwood Formation (Phanerozoic | Paleozoic | Cambrian Ordovician) at surface, covers 10 % of this area

Whitewood Limestone (Ordovician)- Mottled, tan, gray to lavender, fine- to medium-crystalline, sparsely fossiliferous limestone and dolomite. Thickness up to 70 ft (21 m). Winnipeg Formation (Ordovician)- Grat and light-green, fissile shale, and tan, calcareous siltstone, sandy shale, and limestone lenses. Thickness up to 110 ft (34 m). Deadwood Formation (Ordovician to Cambrian)- Variegated, yellow to red, brown, gray, and green, glauconitic, conglomerate, sandstone, shale, dolomitic limestone, and dolomite. Thickness 4-400 ft (1-122 m).

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

Alluvium and Colluvium (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers < 0.1 % of this area

ALLUVIUM AND COLLUVIUM--Clay, silt, sand, and gravel in flood plains, fans, terraces, and slopes.

Lithology: alluvium; colluvium

Metabasalt (Proterozoic | Paleoproterozoic) at surface, covers 1 % of this area

Dark-green amphibolite, actinolite schist, and greenstone. Interflow units consists of graphitic schist, chert, and carbonate- and silicate-facies iron-formation. Thickness of individual flows 50-400 ft (244-1,524 m).

Lithology: amphibolite; schist; greenstone; chert; iron formation

Metagraywacke (Archean(?) Proterozoic | Paleoproterozoic) at surface, covers 0.5 % of this area

Gray, siliceous mica schist and impure quartzite. Thickness undetermined.

Lithology: schist; quartzite

Metagabbro (Proterozoic | Paleoproterozoic) at surface, covers 0.4 % of this area

Dark-green sills of amphibolite, actinolite schist, greenstone, and serpentine. Thickness of sills variable, up to 1,000 ft (305 m).

Lithology: amphibolite; schist; greenstone; serpentinite

Trachytic Intrusive Rocks (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene) at surface, covers 2 % of this area

Tan to reddish-brown, iron-stained stocks, laccoliths, sills, and dikes of trachyte, quartz trachyte, and alkalic rhyolite. Contains phenocrysts of sanidine, orrthoclase, anorthoclase, aegirine-augite and biotite in a finely crystalline orthoclase-quartz biotite groundmass.

Lithology: trachyte; trachyte; rhyolite