1.1 Earth Systems
Geology is an umbrella science that encompasses all biological, chemical, and physical processes that act on the planet and make up our world. In the same way that the human body can be divided into systems (circulatory, digestive, endocrine, etc.), the Earth can be described as a complex entity that encompasses many different systems all acting on one another. There are 5 main systems, or spheres, found on Earth: geosphere, biosphere, hydrosphere, atmosphere, and cryosphere.
Geosphere (“geo” = Earth)
The geosphere encompasses all physical material that makes up the interior and surface of the Earth. This includes all rocks and minerals, but is also includes the active processes that link these rocks and minerals together. While many tend to focus on the three types of rocks: igneous, sedimentary, and metamorphic, the forces of plate tectonics and weathering actively change rocks from one type to another. This system is referred to as the Rock Cycle. This is the focus of most physical geology courses and will be the main framework for this text. Because the geosphere describes the physical structure of the Earth, it is integral to all other spheres as well.
Biosphere (“bio” = life)
The biosphere is made up of all living things, as well as the ecosystems that support that life. Obviously, life can be found in many different places, from the tops of mountains to the bottoms of oceans, in wet and dry places, in cold and hot environments. The biosphere therefore overlaps and interacts with all other spheres.
Hydrosphere (“hydro” = water)
The Earth has been described as the “Blue Marble” in space due to the presence of enormous amounts of water on its surface. All of the liquid water found on earth makes up the hydrosphere. As water flows on the Earth’s surface, it changes landscapes and nourishes life, and interacts with all other spheres.
Atmosphere (“atmo” = vapor)
All of the gases that circulate around and surround the earth are a part of the atmosphere. This includes the air we breathe, the gases that are responsible for global weather and climate, as well as the ones that burn up meteorites as they plummet toward the Earth’s surface. The atmosphere is further broken into layers: troposphere, stratosphere, mesosphere, thermosphere, and exosphere.
Cryosphere (“cryo” = frozen)
Cryo- comes from a Greek word meaning “frost.” The cryosphere encompasses all of frozen water on the Earth. Typically found at high elevations and at the poles, ice can have dramatic impacts on landscapes (geosphere), provide sources of liquid water (hydrosphere), and support ecosystems for living things (biosphere).
Integrated systems
While it is easier to look at each system independently, they are all integrated on the Earth. Each one is constantly acting and interacting with another on our dynamic planet.
H2O, or the water molecule, is constantly changing. It is the only substance on Earth that is present in all states of matter – solid, liquid, and gas. The cycling of water throughout the Earth, also called the hydrologic cycle, describes how water moves through various environments on Earth. The largest reservoir of water is in the ocean, and it exists there as a liquid. Through the process of evaporation, it becomes a gas. At that point, it may crystallize as a solid (snow or ice) and deposit on land. It could then melt, forming a liquid again, and run off the landforms, eternally shaping the Earth. It can be taken up into plants, aiding in photosynthesis, and released as a gas through the process of transpiration. The possibilities of pathways for water to travel on Earth are endless.
Backyard Geology: Spheres intersect for one of the 7 Natural Wonders of the World
Arizona is known as the “Grand Canyon State” because of the dramatic landscape that unfolds at the intersection of brightly colored flat-lying sedimentary rocks and a dynamic river system. This landscape evolved over millions of years while the underlying rocks were uplifted by Plate Tectonics, and the Colorado River cut down through soft sedimentary rocks..
***See 1.5 for Text and Media Attributions
Rocks that crystallize from molten materials beneath the Earth surface or from volcanic processes.
rocks that cement together from weathering products, either from sediments or chemical ions in water.
Rocks that form when any type of preexisting rock is warped or transformed under elevated temperatures and pressures.
The theory that the outer layer of the Earth (the lithosphere) is broken in several plates, and these plates move relative to one another, causing the major topographic features of Earth (e.g. mountains, oceans) and most earthquakes and volcanoes.
The process of physically or chemically breaking down, transforming, or dissolving existing rock with contact by water, the atmosphere, or biosphere.
lowest layer of the atmosphere where weather takes place. Up to 10km.
10-50 km from Earth's surface. Contains ozone, vital in protecting the planet from ultraviolet light.
The physical layer in the Earth's mantle that lies between the asthenosphere and the core.
500-1000km above Earth. Very hot, temperatures can reach 2000C.
Can extend up to 190,000km above Earth. Extremely thin air.
process of evaporation that changes liquid and frozen water into water-vapor gas, which then floats up into the skies to become clouds.
The total of water evaporated from the land surface plus transpiration from plants
