The Colour of Sand

Sand is rock eroded over thousands, or even millions, of years. Freezing and thawing cracks bedrock, ice and water carry rocks down slopes, and water and waves break them down further until all that remains of the original rock is grains of sand.

Beaches with pebbles or coarse sand are relatively young in geological terms – the pebbles have not been there long enough to be eroded down to finer sand.

Beaches with fine sand are older - erosion has had more time to break the rock down to finer grains.

The color of sand depends on the original rock it came from. For example, the red sand at Cabots Landing Provincial Park in Cape Breton eroded from rock with significant iron content. Iron oxidizes/rusts when exposed to air, so the red in the sand is rusted iron. This is also the case for PEI’s beautiful red sand and soil.

Most Nova Scotia beaches are a tan or brownish colour because their sand eroded from granite that contains iron oxide, which gives the granite a light brown colour, and/or feldspar which is brown to tan in its original form.

Not surprisingly, white sand comes from source material that was white or at least light-coloured. Carter’s Beach and several others in the area are white because their sand eroded from light-coloured granite. White sand also often comes from white quartz or limestone, which contains calcium carbonate, a mineral also found in chalk and human bones.

On the other hand, Thomas Raddall Provincial Park’s beach, a little further down the South Shore from Carter’s Beach, is less white because it also contains sand eroded from darker metasandstone. (The “meta” in metasandstone is short for metamorphose, which comes from the Greek word for change. Metasandstone is sandstone that has been changed by heat and/or pressure into a new type of rock.)

The beach at Cape Breton’s Marble Mountain is white because it is mainly crushed and eroded marble from historical mining at the site (see our history of Marble Mountain at https://notyourgrandfathersmining.ca/marble-mountain)

There are other colours of sand, too. For example, black sand comes from eroded volcanic material such as lava, basalt rocks, and other dark-colored rocks and minerals, and is typically found on beaches near volcanic activity. Black-sand beaches are common in Hawaii, the Canary Islands, and the Aleutians.

The by-products of living things can also play an important role in creating sandy beaches. White tropical beaches are often pulverized pieces of dead coral, which is white because it is made of calcium carbonate, like limestone.

Hawaii’s white sand beaches come from the poop of parrotfish! The fish bite and scrape algae off rocks and dead corals with their parrot-like beaks, grind up the inedible calcium-carbonate reef material in their guts, and then excrete it as sand. At the same time that it helps to maintain a diverse coral-reef ecosystem, parrotfish can produce hundreds of pounds of white sand each year!

Bermuda's pink beaches result from single-celled organisms called foraminifera that have red-pink shells. As the foraminifera die, they sink to the ocean floor and become part of the sand on the beaches.

Whatever the colour of the sand, it’s always great to visit Nova Scotia’s many beautiful beaches!