Water And Oceanography

Colors of Sand on Beaches Rainbow Beaches Formation of Colored Sand



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Most people have seen the fine grains of sand on a beach along a lake or ocean.  Sand is formed over millennia when larger rocks are broken down into smaller and smaller particles by mechanical erosion or weathering.  This is caused by freeze/thaw cycles, erosion from water, and fractures from various impacts.  After mechanical breakdown of rock, chemical weathering also occurs.  Some of the causes of this are acid rain and the chemicals that are released by various marine organisms.

When the particles are finally small enough, they become sand, and they can be tossed around by water and wind.  Beaches are formed over long periods of time by the action of waves, wind and currents on the sand particles.  The composition of a beach is determined by the nearby uplands and also by the ocean bottom near where the beach is formed. 

Because of this, the sand of beaches in different locations can vary a great deal in color.  While most beaches are cream to golden brown or gray and are most commonly composed of the minerals quartz or feldspar, there are some more unusual ones that occur, including white, red, pink, green and even black.  Nearby upland gemstone areas, local volcanic activity, or crushed marine coral can lead to the formation of a rainbow of sand colors.  

White

There are a few famous beaches composed of very pure quartz that is almost as fine in texture as powdered sugar.  Two of these are Siesta Key’s Crescent Beach in Florida and Hyams Beach in New South Wales, Australia.  The sand on these beaches is white.  Hyams beach is recognized by the Guinness Book of World Records as having the whitest sand in the world.  However, Crescent Beach, which previously won the Great International Sand Challenge for the whitest sand in the world, has sand which is composed of 99% pure quartz that began in the Appalachain mountains, flowing down rivers to become part of the deposits along the coast.

Red

On the Hawaiian island of Maui, Kaihalulu Beach is composed of sand that is dark red in color.  This color occurs because the sand is rich in iron, as it comes from a crumbling cinder cone volcano.  Although rare, other red sand beaches can be found in the Galapagos Islands and in Santorini, Greece.  

Pink

Beaches with pink sand occur near areas that have coral reef formations.  In the coral reefs, there is a tiny organism with a red skeleton that falls to the ocean floor when the organism dies.  These skeletons are eroded by the waves and the small particles that result are mixed with the sand, creating the pink color

Green

Hawaii has many beaches with unusual sand colors due to the history of volcanic activity and the number of old eroding volcanoes.  One of the minerals that erodes from cinder cones is olivine, which is a component of lava and one of the first crystals to form as the magma cools.  Olivine contains magnesium and iron, and gem quality olivine is known as peridot, the popular gemstone, whose color is a deep, rich green.  Papakolea Beach, near an old cinder cone known as Pu’u Mahana, has sands with olivine, giving the beach a green color that is very rare.

Black and Rainbow

In countries where there has been volcanic activity, the cooled lava hardens into black rock, and over millennia, the rock erodes into particles and washes down to shore, creating a black sand beach.  These can be found, again, in the Hawaiian Islands, as well as in California, the Dominican Republic, Greece, Argentina and the South Pacific Islands.  Various gemstones can sometimes also be found on such beaches, since they can form within volcanoes and later be spewed out with eruptions.

When various rocks and minerals are mixed in upland cliffs, such as during an Ice Age, a whole rainbow of colors can be displayed.  This is the case at Rainbow Beach, at Fraser Island in Australia.  The sand, with its variety of colors, is part of an aboriginal legend.  The Kabi tribe, who were the early inhabitants of the area, spoke of Yiningie, the spirit of the gods, who was represented by a rainbow.  Yiningie was killed in a fight and crashed into the local cliffs, and his spirit colored the sand for all time.

So it can be seen that the activity of nature, over long periods of time, can create a palette of colors on the sand beaches of the world.  This is just another piece of very visual evidence of the well-known fact that everything in the earth’s environment is connected, and it is illustrated vividly, in living colors. 






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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://. http://coastalcare.org/educate/beach-basics/
  • InfoBoxCallToAction ActionArrowhttp://coastalcare.org/2010/10/dream-in-color-on-the-worlds-rainbow-beaches/
  • InfoBoxCallToAction ActionArrowhttp://, http://beaches.uptake.com/blog/rainbow-beaches-colored-sand.html
  • InfoBoxCallToAction ActionArrowhttp://www.greeka.com/cyclades/santorini/santorini-beaches/santorini-red-beach.htm
  • InfoBoxCallToAction ActionArrowhttp://www.harbourislandguide.com/pink-sands.htm
  • InfoBoxCallToAction ActionArrowhttp://www.rainbowbeachqld.com/rainbow_history.html