The Earth System
The systems that Hutton claimed to be linked can best be described in terms of spheres of influence that are not necessarilly separate from one another but physically occupy different areas in space. Of these, the sphere we are all most familiar with is that of the solid earth, the geosphere. Surrounding the geosphere is the atmosphere, composed of nitrogen oxygen, carbon dioxide, water, and countless other lesser materials (which by no means make them any less important). From space the atmosphere is a thin blanket covering the solid earth.
Although it extends only 16 kilometers above the Earth's surface the atmosphere plays a crucial part in all Earth systems. The atmosphere provides the air we breathe, it protects us from harmful ultra-violet radiation and moderates global temperatures by absorbing infrared energy. Without the atmosphere the Earth would be a cold inhospitable wastland and much of the processes that create what Hutton called a dynamic planet would cease to operate. The atmosphere also provides much of the mechanism that allows the interaction of Earth's systems. It is the exchange of energy that occurs between the solid earth and the atmosphere that leads to the weather we experience. This in turn allows for the invaluable interaction of, not only, the atmosphere and the solid earth, but also the hydrosphere.
The hydrosphere is composed of an enormous amount of water. Roughly 71% of earth's surface is covered by an average depth of 3,800 meters of water, but that is only a portion of the water on the planet. The hydrosphere also contains all the fresh water lakes, streams, glaciers, groundwater, and the evaporated water that is floating around the atmosphere. It is no wonder our planet is often referred to as the blue planet.
Even more facinating than the sheer amount of water is the fact that all of this water is continually in motion. Water is constantly moving beneath the surface in underground aquifers where it slowly dissolves soluble minerals and transports them on its way to the ocean or to lakes and streams (that eventually bring it to the ocean). This moving water both above and below the surface, over time, is responsible for shaping the surface of the earth and carving out many of the landforms we are familar with.
Once in the ocean the motion doesn't stop through ocean currents water is continually cycled across the planet from the equator to the poles and back again. All the while, at the surface, it is evaporated where it is transformed into rain only to fall back on the land as fresh water to start the cycle over again.
Without the constant interaction of the solid earth, the atmosphere, and the hydrosphere the biosphere could not exist. The biosphere includes all life on the planet and although we tend to think of life as only existing on the surface of the earth the biosphere actuallt extends from the depth of the ocean floor up thousands of meters to the lower atmosphere.
What makes Earth such a dynamic planet is how all these spheres interact. By changing just one variable in any sphere we may see dramatic and sometimes hazardous affects in the other three. Take for example the hole in the ozone layer. The ozone layer exist high above the earth in the upper atmosphere and consists of high quantities of Ozone (O3) . At earth's surface ozone acts as an irratant to most people and in some cases can be quite toxic; however, without it life probably wouldn't be be able to exist.
In the upper reaches of the atmosphere, ozone blocks harmful ultra-violet radiation from reaching the surface. Unfortunately, as synthetic chemicals pollutants, such as CFC's, reach the upper atmosphere they react with ozone and interupt the u-v blocking process that protects us hundreds of thousands of feet below. Without the ozone layer greater levels of UV radiation will reach the surface which could have drastic effects on life, once again illustrating the interaction of all Earth's systems.