how is sand that flows in a river formed and where the sand come from?
Answers
Sand is a result of the breakdown of Earth’s crust. Sand is formed over a long period of time by water, wind, gravity, and tectonics, among other forces. Water provides movement of sediment from the beginning of streams and inland areas down through the land. As sediment is transported it becomes more worn. While heavier sediment settles along river banks and streams, lighter sediment gets carried to the ocean. Gravity assists the motion of material down streams, rivers, and cliff sides. The smashing of rocks together causes fragmentation of rocks. Like gravity, wind contributes to the movement of materials in powering waves, currents, and the eroding of surfaces. Fine sand is also transported to various locations by the wind. Plate tectonics work together with gravity and water to push rocks upward and then wear them down. These are some common causes that construct sand but depending on location others may exists, such as animal involvement.
These forces cause decomposition of the Earth’s crust to make fine sediment we refer to as sand. Depending on where you are located sand can look different. Different region’s sands are composed of various materials. California for example has many beaches composed of quartz grains. Quartz grains are minerals found in many different kinds of sedimentary rocks and igneous rocks found in Earth’s crust. Once the sedimentary and igneous rock is weathered away, quartz grains are what remains due to ability to resist weathering. Other locations such as the Hawaiian Islands have beaches that are composed of parrotfish poop. Parrotfish consume coral when biting and scraping algae off dead coral, this coral is then passed through their intestines and excreted. Other beaches in New Zealand are referred to as black sand beaches because of their black color which is a result of being composed of volcanic lava fragments. Yet others are made entirely of shells like those in West Australia. Thus, every beach with its abundant sand always has a story of how it came to be formed.