South-Dakota-geology

Fairburn fortifications

The state gemstone of South Dakota is one of the most beautiful agates on Earth, with lovely banding patterns and (in the best specimens) bright red, orange and brown colours due to iron oxides. Named after the town nearest to where it occurs, it is a target for rockhounds across the country (see http://on.fb.me/16fsEEt). They were first discovered in the late 19th century, though native peoples had known of them since time immemorial.

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Cotton-candy yellows and pinks color the hills of Badlands National Park in South Dakota. The Badlands’ striking formations contain one of the world’s richest fossil beds, carrying clues to ancient mammals like rhinos and saber-toothed cats that once roamed here. Photo by Brenda Bergman (www.sharetheexperience.org).

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Nice driveby road view of the sandstone pillars in Badlands National Park

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Falls Park South Dakota, waterfall on the Big Sioux River. The water is tumbling over the Sioux quartzite, a thick, metamorphosed sequence of 2.1 billion year old, precambrian river deposits. Now fractured and jointed after coming up to the surface, the fractures give the river a path through the otherwise difficult to erode rock.