Purple sand explained

Purple beaches are a phenomenon caused by the presence of a large amounts of almandine-pyrope garnet.[1] [2] or other purple minerals like manganese[3] or rose quartz that have accumulated in the local sediment. These purple beaches are primarily found in the western Canadian Shield region or the northern continental United States; often in proximity to a major river systems with coarse sediment, a glacial sediment source, or input from glacial or para-glacial sediment.[4] Purple sand can also be caused by purple paint mixing with the quartz in sand.

Causes

Surficial garnet deposits primarily originate from the glacial erosion of plutons, with the majority from the glacial erosion of the Canadian Shield caused by ice flow during retreat of the Laurentide Ice Sheet.[5] These beaches often have stripes of various colors or shades caused by the waves sorting the minerals by density and therefore color. As a wave comes ashore it pushes less-dense minerals higher up the beach while denser minerals settle first.[6] The relatively low density of the garnet causes it to rise to the top of the sand giving the beaches their unique color.[7]

Purple Sand Beaches

Notes and References

  1. Web site: Why is the Sand Purple at Plum Island Beach? . JEOL USA . 16 November 2021.
  2. Book: Sepp, Siim . 16 May 2013 . Pfeiffer Beach sand . 16 November 2021.
  3. Web site: Clearwater Lake Provincial Park Management Plan . . January 2013 . Manitoba Conservation and Water Stewardship Parks and Natural Areas Branch . 18 Nov 2021.
  4. Christopher J. . Hein . etal . 1 Jan 2014 . Evolution of para-glacial coasts in response to changes in fluvial sediment supply . London Geological Society Special Publications. 388 . 15 . 270 . 10.1144/SP388.15 . 2014GSLSP.388..247H . 129662471 . 19 November 2021.
  5. Book: Eccles, D.R. . 2008 . Geological Evaluation of Garnet-Rich Beaches in East-Central Alberta, with Emphasis on Industrial Mineral and Diamondiferous Kimberlite Potential . Energy Resources Conservation Board . 23 November 2021.
  6. Book: Bob . Turner . Marianne . Quat . Ruth . Debicki . Phil . Thurston . 2015 . Natural Resources Canada and Ontario Geological Survey 2015. Parry Sound: Canadian Shield and glacier-sculpted gneiss in cottage country; GeoTours Northern Ontario series. . 23 November 2021.
  7. Web site: 6 Natural Wonders You Must Experience in Saskatchewan . Jay . Brown . 9 February 2016 . 18 November 2021.
  8. Web site: Canada's little-known geological wonder . Ryan . MacDonald . 11 February 2020 . BBC . 18 November 2021.
  9. Web site: Some of the best beaches in Canada! . Tourism Saskatchewan . 18 November 2021.

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