Beach sand is more than just tiny particles beneath our feet. It holds secrets about the land it came from and the long journey it took to reach the sea. Mountains play a crucial role in the formation of beach sand as they erode over time.
As mountains erode, they release mud, sand, gravel, cobbles, and boulders that are carried by streams and rivers towards the sea. Along the way, these sediments are broken down into smaller pieces, with most of it turning into mud. The sand particles we see on beaches are larger bits of rocks that have traveled a certain distance.
When you pick up a handful of sand at the beach, you may notice different colors and textures. These variations in color come from different minerals in the rocks, such as feldspar, quartz, olivine, and basalt. The shape of sand grains can also indicate their origin, with angular grains suggesting a shorter travel distance compared to smooth, round grains.
Approximately 10% of the sediment that reaches the sea is sand, with particles ranging from half a millimeter to 2 millimeters in size. These particles are crucial for maintaining sandy beaches, as they are too large to flow directly into the deep sea. However, many beaches are facing erosion due to the lack of sand replenishment.
Human activities, such as dam construction, have interrupted the natural flow of sand to beaches, leading to shoreline erosion in many coastal areas. Despite efforts to replenish eroded beaches with new sand, the problem persists, causing beaches to shrink over time.
It’s essential to consider the journey that beach sand has taken when we enjoy a day at the seaside. Reflecting on the origins of sand and its fate can help us appreciate the intricate processes that shape our coastlines. David R. Montgomery, a Professor of Earth and Space Sciences at the University of Washington, sheds light on the fascinating story of beach sand and its significance in coastal ecosystems.
