Sand is one of many things vital to life on Earth, but we generally ignore the connection between sand and life. Sand comes in many different colors and chemical compositions. Silicon and oxygen make up the sand in the Great Lakes area where we live, while Florida’s sand consists of calcium and oxygen. Sand has multiple uses in construction, and it can hold large amounts of water, making it useful in water resources. Because water flows very slowly through sand, we use it in bags to stop the rapid flow of water. Sand mixed with organic material makes soil. Sand and life are closely tied together.
In the northern parts of the world, most of the sand results from the breakdown of granite and other volcanic rocks. Granite contains orthoclase, a pinkish mineral that dissolves into clay. The orthoclase is mixed with other dark-colored minerals that break down, and water carries them away. The toughest material in granite is the last to remain, and it weathers into sand.
I had a college professor who took us to a cemetery to look at the headstones. Dates were carved into the headstones, so we knew how long they had been exposed to the elements of wind, rain, and ice. In the oldest section of the cemetery, the headstones had been reduced to sand because they were made of granite which breaks down. Limestone headstones get tougher with time and generally survive longer.
The world’s oceans have a different connection between sand and life. For example, parrotfish produce 70% of the sand in the Pacific Ocean. These fish eat coral, biting off small chunks and digesting the organic material in the coral polyps. The fish discharge what is left, and it falls to the ocean floor as sand. In areas of the world rich in clams, oysters, snails, and other sea animals with shells, much of the sand is produced by waves grinding up the shells of these creatures.
Lake Michigan’s beaches look very different from those in Florida. Sand in Lake Michigan comes from granite that has been broken down by plant roots and the freezing and thawing of water. The beach sand contains granules of magnetite (an iron mineral) and other dark-colored minerals. In Florida, the sand is ground up of seashells with no dark minerals, making it very white. Some sand near volcanic activity will be green or black as the dark soluble minerals have not had time to weather out.
The processes that produce sand and other materials critical to life on this planet show design. Interactions between the elements and living things enable life forms to adapt to their environments in various climates and conditions. The more we study and understand the processes and how they interact, the more we see that a wonder-working hand has gone before to prepare a place for humans to dwell.
— John N. Clayton © 2022
Reference: Planet Earth airing on PBS April 8, 2022.