Geosphere
The geosphere, or "Earth-sphere," refers to the complex system of geological components that make up the Earth, extending from its surface to its core. This system includes the layers of the Earth’s interior—namely the core, mantle, and crust—as well as external features like the atmosphere, hydrosphere, cryosphere, and lithosphere. The core is primarily composed of iron and nickel, with an extremely hot inner core surrounded by a cooler outer core. The mantle, the largest layer by volume, is mostly rock and undergoes convection due to heat from the core, influencing tectonic movements that can shape the surface. The crust, Earth's outermost layer, is divided into oceanic and continental varieties, each composed of different materials.
Above the crust, the hydrosphere encompasses all of Earth's water, while the cryosphere includes frozen water, primarily in polar regions. The atmosphere contains the gases surrounding the planet, facilitating the water cycle that replenishes Earth's surface. The lithosphere, which includes rocky formations, is subject to weathering and erosion, contributing to the rock cycle. The interactions within the geosphere are crucial for maintaining life on Earth, influencing climate, natural resources, and geological events. Despite technological advancements, humans have limited control over these dynamic processes, which continue to shape the planet.
Geosphere
Far more than just a mass of material in space, Earth is a complex and ever-changing system containing many different parts and elements. The term geosphere (which means "Earth-sphere") refers to the combination of all the natural geological components that form Earth. These various components extend from the air above the surface down to the center of the planet. The components of the geosphere interact and work together to form the planet and influence the many systems and cycles that allow life to thrive here. Plants, animals, and other living things on the planet are considered part of the "biosphere" (which means "life-sphere") and are not generally included in the geosphere.
The geosphere comprises many parts. The interior of the planet contains roughly spherical layers of material known as Earth's core, mantle, and crust. Meanwhile, the atmosphere, hydrosphere, cryosphere, and parts of the lithosphere exist on the exterior of the planet.
Overview: Interior Components
The lowest and deepest component of the geosphere is the core of Earth. The core contains mostly iron but has some nickel as well. The innermost part of the core is extremely hot due to intense pressure, and the heat keeps the iron in a perpetually molten, liquid form. The inner core is about 1,500 miles thick. Surrounding the inner core is an outer core region. Here, metals are able to cool into a mostly solid form. The outer core is about 750 miles thick. The iron in the core, being a highly magnetic metal, gives Earth its magnetic field.
Surrounding the core is the planet's mantle, a layer that contains the greatest volume of material within Earth's interior. This material is primarily rock, though a significant quantity of metal, mostly iron and magnesium, is also present. Like the core, the mantle is divided into two parts. The inner part has denser material and is somewhat plastic, meaning it can change shape without breaking. The outer part, which is sometimes called the asthenosphere ("weak-sphere"), is less dense but more brittle. The mantle is in constant motion due to the enormous heat of the core locked within it. The heat causes convection—rising and sinking—in the rocks of the mantle.
Surrounding the mantle is the next internal layer, the crust. At approximately three miles to forty-five miles in thickness, the crust is relatively thin compared to the two huge layers beneath it. The crust comprises two varieties, namely oceanic crust and continental crust. Oceanic crust is usually thinner and contains mostly silicon, oxygen, and magnesium. This is the crust beneath the many oceans of the planet. Continental crust, the crust beneath Earth's landforms, is thicker. It may contain hundreds of types of rocks, minerals, and other elements, but oxygen, silicon, aluminum, and iron are the most common.
The crust is greatly affected by the convections within the mantle. Scientists believe mantle movements cause large sections of the crust to shift over time. This process, called tectonic shifting, can greatly impact the surface of the planet by creating mountains or causing volcanic eruptions or earthquakes.
Although the interior of Earth is vitally important to life on the surface, people have little direct knowledge of it. Due to limits in technology, scientists have been unable to directly research layers deeper than about six miles. All information about the vast depths of Earth has come indirectly through scientific analyses in petrology (the study of rocks), seismology (the study of earthquakes), and other geologic fields.
Exterior Components
Situated over the crust layer is the surface of the planet, the part of Earth where people, plants, and animals live. Like the interior of the planet, the surface also features important components of the geosphere. These features include the hydrosphere, cryosphere, atmosphere, and parts of the lithosphere.
The hydrosphere ("water-sphere") includes all the water on the surface of the planet. About 70 percent of the surface is covered in water, both freshwater and saltwater. Much of this water, particularly in the polar regions, is permanently frozen. The vast amounts of ice on the surface make up the cryosphere ("ice-sphere"). Meanwhile, water that evaporates rises into the atmosphere ("vapor-sphere"), which is the gas-filled air surrounding the surface of the planet. Most of the water will later return to Earth as precipitation, thus concluding the water cycle, which is one of the primary processes accomplished by the geosphere.
The lithosphere ("stone-sphere") includes the rocky formations on the outside of the planet. On the surface, people can see the clearest evidence of the lithosphere in mountains, which are often formed by tectonic action pushing deep rock up toward the surface. These exposed rocks are then subjected to alteration, weathering, and erosion by moving water, climatic change, and other natural forces. This endless process of change is known as the rock cycle. (Below the surface, the crust and upper mantle are also considered part of the lithosphere.)
The geosphere, both inside and outside the planet, is vitally important to the biosphere, or the system of life on Earth. Changes in geospheric factors can cause innumerable changes to the planet, such as movement of the continents, variations in climate, distribution of natural resources, and destructive natural disasters. These changes may bring vast repercussions to the humans, plants, and animals of Earth. Although humans have undergone great technological and scientific advances and attempted to tame the environment on the planet's surface, humans ultimately have very little control over the overall dynamics of Earth's geosphere.
Bibliography
Bengtsson, Lennart O. and Claus U. Hammer, eds. Geosphere-Biosphere Interactions and Climate.New York: Cambridge University Press, 2001. Print.
Desonie, Dana. Geosphere: The Land and Its Uses.New York: Chelsea House, 2008. Print.
"The Geosphere." Aspen Global Change Institute. Aspen Global Change Institute. Web. 19 Nov. 2014. <http://www.agci.org/classroom/geosphere/>
"Geosphere Resources." Museums Teaching Planet Earth/University of California, Santa Barbara. Museums Teaching Planet Earth/UCSB Node. Web. 19 Nov. 2014. <http://www.geog.ucsb.edu/~dylan/mtpe/>
"Museums Teaching Planet Earth." Rice University Physics & Astronomy Department. Rice Space Institute. Web. 19 Nov. 2014. <http://earth.rice.edu/mtpe/>
Sharp, Tim. "What is Earth Made Of?" Space.com. Purch. Web. 19 Nov. 2014. <http://www.space.com/17777-what-is-earth-made-of.html>
Tomberlin, James A. "Geosphere and Biosphere Diagram." U.S. Geological Survey. U.S. Geological Survey. Web. 19 Nov. 2014. <http://pubs.usgs.gov/pp/p1386a/plate-earthsystem.html>
Zheng, Yan, et al. "Environmental Earth Sciences: Advancing Geosphere Plus Knowledge for Environmental Problem Solving." Environmental Earth Sciences, vol. 82, no. 445, 7 Sept. 2023, doi.org/10.1007/s12665-023-11089-6. Accessed 20 Nov. 2024.