Four Spheres Essay

666 Words3 Pages
Everything in the earth's system can be put into one of four major subsystems: land, water, living things, or air. The four subsystems are called spheres. The spheres are the lithosphere land, hydrosphere water, biosphere living things, and the atmosphere air. These four spheres can be divided into sub-spheres. Lithosphere The lithosphere contains all of the cold, hard solid land of the planet's crust (surface), the semi-solid land underneath the crust, and the liquid land near the center of the planet. *The surface of the lithosphere is very uneven (see image at right). There are high mountain ranges like the Rockies and Andes (shown in red), huge plains or flat areas like those in Texas, Iowa, and Brazil (shown in green), and deep valleys along the ocean floor (shown in blue). The solid, semi-solid, and liquid land of the lithosphere form layers that are physically and chemically different. If someone were to cut through Earth to its center, these layers would be revealed like the layers of an onion (see image above). The outermost layer of the lithosphere consists of loose soil rich in nutrients, oxygen, and silicon. Beneath that layer lies a very thin, solid crust of oxygen and silicon. Next is a thick, semi-solid mantle of oxygen, silicon, iron, and magnesium. Below that is a liquid outer core of nickel and iron. At the center of Earth is a solid inner core of nickel and iron. Hydrosphere The hydrosphere contains all the solid, liquid, and gaseous water of the planet. **It ranges from 10 to 20 kilometers in thickness. The hydrosphere extends from Earth's surface downward several kilometers into the lithosphere and upward about 12 kilometers into the atmosphere. A small portion of the water in the hydrosphere is fresh (non-salty). This water flows as precipitation from the atmosphere down to Earth's surface, as rivers and streams along Earth's

More about Four Spheres Essay

Open Document