File:Sioux Quartzite (Paleoproterozoic, 1.65-1.70 Ga; Falls Park, Sioux Falls, South Dakota, USA) 5.jpg

English: Water-worn & sculpted quartzite in the Precambrian of South Dakota, USA.

Extensive outcrops of pinkish, Paleoproterozoic-aged quartzites are present at Falls Park along the Big Sioux River in the city of Sioux Falls, southeastern South Dakota, USA. The quartzites here have nicely water-worn, sculpted surfaces with good, fluvially abraded polish in places. These rocks are part of the Sioux Quartzite (Paleoproterozoic, 1.65-1.70 Ga). Despite being subjected to regional metamorphism, this unit’s original sedimentary features, such as horizontal stratification and ripple marks, are still preserved.

The Sioux Quartzite is a famous erosion-resistant unit in America’s midcontinent. It has formed a long-lived paleotopographic high since Precambrian times - the Sioux tectonic core. This high is part of a NE-SW trending series of paleotopographic highs & depressions known as the Transcontinental Arch, which extends from Arizona to Minnesota (see Carlson, 1999).

The Sioux Quartzite has been and still is quarried in the town of Sioux Falls. Material from these quarries is used as road gravel, sidewalk and paving gravel, and erosion control blocks.

Stratigraphy: Sioux Quartzite, upper Paleoproterozoic, 1.65-1.70 Ga

Locality: Falls Park, near Sioux Falls along the Big Sioux River in the town of Sioux Falls, southeastern South Dakota, USA

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Reference cited:

Carlson (1999) - Transcontinental Arch - a pattern formed by rejuvenation of local features across central North America. Tectonophysics 305: 225-233.