USGS Home
Contact USGS
Search USGS

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

Geologic units in Pipestone county, Minnesota

Migmatitic gneiss, amphibolite, and granite (Middle to Early Archean) at surface, covers 26 % of this area

Migmatitic gneiss, amphibolite, and granite - Montevideo and Morton Gneisses (3600-3000 m.y.) in the Minnesota River Valley, southwestern Minnesota; McGrath Gneiss (2750 m.y.) east of Mille Lacs Lake; components of Hillman Migmatite southwest of Mille Lacs Lake; and Sartell Gneiss in Stearns County. Inferred to include various younger rocks, including granitoid intrusions in the Hillman Migmatite and pillowed basalt in poorly exposed areas of southwestern Minnesota.

Lithology: gneiss; amphibolite; granite; basalt

Outwash, Valley Train (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers < 0.1 % of this area

Heterogeneous silt to gravel. Confined to valleys of glaciofluvial orgin. Thickness up to 60 ft (18m).

Lithology: silt; sand; gravel

Alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers < 0.1 % 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

Outwash, Collapsed (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers < 0.1 % of this area

Heterogeneous sand and gravel of glaciofluvial orgin. Deposited as outwash sediments that collapsed due to melting of buried ice. Thickness up to 90 ft (27m).

Lithology: sand; gravel

Outwash, Undifferentiated (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Upper Wisconsin]) at surface, covers < 0.1 % of this area

Heterogeneous sand and gravel, with minor clay and silt. Deposits of glaciofluvial orgin including outwash plains, kame terraces, and other undifferentiated deposits. Thickness up to 30 ft (9m).

Lithology: sand; gravel; clay or mud; silt

Cretaceous rocks, undivided (Cretaceous) at surface, covers 7 % of this area

Cretaceous rocks, undivided - Dakota, Graneros, Greenhorn, Carlie, Niobara, and Pierre formations and their nonmarine equivalents in northwestern, southwestern, and southeastern Minnesota

Lithology: shale; sandstone; limestone

Sioux Quartzite (Early Proterozoic) at surface, covers 66 % of this area

Sioux Quartzite - Red quartzite of fluvial to possibly marginally marine origin. Includes quartz-pebble conglomerate, claystone (catlinite, also called pipestone), a basal (rhyolite) pebble conglomerate in Pipestone County, and a basal (granite, quartz, chert, iron-formation) conglomerate in Nicollet County on the Minnesota River

Lithology: quartzite; conglomerate; claystone

Till, Ground Moraine (Phanerozoic | Cenozoic | Quaternary | Pleistocene [Illinoian(?)]) at surface, covers < 0.1 % of this area

Heterogeneous, clay with silt to boulder-size clasts. Exhibits a distinctive weathered, dissected surface. Contains prominent oxidized joints and fractures with gypsum or calcite. Typically overlain by up to 25 ft (8 m) of loess. Thickness up to 120 ft (37 m).

Lithology: clay or mud; silt; sand; gravel