Earth As A System
A system is an organized group of parts that work together to form a whole. The Earth is made up of 4 major parts: Atmosphere, Hydrosphere, Biosphere, Geosphere.
Atmosphere
Atmo means vapor or gas. The atmosphere is a mixture of gases that surround and protect the Earth (oxygen, nitrogen, etc...). The atmosphere functions to provide living things with oxygen and carbon dioxide, to absorb alter rays from the sun, and to block harmful radiation. The most abundant gas on Earth is nitrogen at 78% followed by oxygen at 21%. That leaves less than1% for all of the other gases on Earth (and there are a lot). Plants produce a lot of oxygen. We need oxygen to breathe and plants need carbon dioxide to live. Without the atmosphere, life as we know it would cease to exist.
Hydrosphere
Hydro means water. The hydrosphere is made up of all the waters on or near Earth's surface (oceans, lakes, above and underground, snow, ice, etc). The hydrosphere provides water for the Earth which is continually recycled. The water you drink today could have been sprayed over a field last year or flowed past the foot of a dinosaur millions of years ago. Water is essential for life. On average a human would die in 3 days without water. Without the hydrosphere, life as we know it would cease to exist.
Biosphere
Bio means life. The biosphere includes all life on Earth; in the air, on land, and in the water. Therefore, the biosphere interacts with the other spheres to support life. Humans, plants, and animals are a part of the biosphere. Without the biosphere, life as we know it would cease to exist.
Geosphere
Geo means Earth. The geosphere is the Earth itself. It includes rocks, continents, islands, sea floor and everything below the surface. Within the geosphere you can find the crust, mantle, outer core, and inner core. Litho means rocky or stone. The lithosphere is made up of the Earth's crust and the upper portion of the mantle. It is composed mostly of rock and soil. Some use lithosphere and geosphere interchangeably. The geosphere is the rock that covers the magma in the mantle. Without the geosphere, life as we know it would cease to exist.
The spheres interact and affect one another.
Examples:
- Volcanoes (geosphere) erupt and send ash and gases into the air (atmosphere).
- Plants (biosphere) get carbon dioxide from the air (atmosphere) and release oxygen back into the air. Humans use some of that same oxygen plants release to breathe and release carbon dioxide. Creating a cycle.
- The oceans cold and warm currents (hydrosphere) interact with the wind patterns (atmosphere) and affect the weather.
The crust is the thinnest layer. It is composed of iron magnesium silicate rocks. The two most common rocks in the crust are granite and basalt. The mantle is the thickest layer. It is composed of silicate rocks that are rich in iron and magnesium much like the crust that surrounds it. Although solid, the high temperatures within the mantle cause the silicate material to be sufficiently ductile that it can flow on very long timescales; acting like a liquid. Beneath the mantle is the core. The core is split into two sections, the outer core and the inner core. The outer core is liquid and believed to be composed of iron mixed with nickel and trace amounts of lighter elements. The inner core is solid metal and believed to be composed primarily of iron and some nickel.
How do scientist study the Earth's Layers? Seismology
When earthquakes occur, they produce seismic waves. Geologists record the seismic waves and study how they travel through Earth. The speed of the seismic waves and the paths they take reveal if the wave is passing through a solid or a liquid and the reflection of the wave reveals how deep the layer is.