Erosion control blocks of Sioux Quartzite (Paleoproterozoic, 1.65-1.70 Ga; Interstate 90 at the Missouri River, Oacoma, South Dakota, USA) : 無料・フリー素材/写真
Erosion control blocks of Sioux Quartzite (Paleoproterozoic, 1.65-1.70 Ga; Interstate 90 at the Missouri River, Oacoma, South Dakota, USA) / James St. John
| ライセンス | クリエイティブ・コモンズ 表示 2.1 |
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| 説明 | Erosion control blocks of Sioux Quartzite (Precambrian) along Interstate 90 at the Missouri River, Oacoma, 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 quarried in southeastern South Dakota and southwestern Minnesota. 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 GaLocality: Interstate 90 at the Missouri River, Oacoma, South Dakota, USA------------------Reference cited:Carlson (1999) - Transcontinental Arch - a pattern formed by rejuvenation of local features across central North America. Tectonophysics 305: 225-233. |
| 撮影日 | 2012-07-01 10:52:00 |
| 撮影者 | James St. John |
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