The Blue Marble

Earth Sciences



Geosciences (another word for earth sciences) are the category of sciences relating to the planet Earth. Notable fields of this are:

Geology is the science and study of the solid matter of a celestial body, its composition, structure, physical properties, history and the processes that shape it. It is one of the Earth sciences. Geologists have helped establish the age of the Earth at about 4.6 billion (4.6x109) years, and have determined that the Earth's lithosphere, which includes the crust, is fragmented into tectonic plates that move over a rheic upper mantle (asthenosphere) via processes that are collectively referred to as plate tectonics. Geologists help locate and manage the earth's natural resources, such as petroleum and coal, as well as metals such as iron, copper, and uranium. Additional economic interests include gemstones and many minerals such as asbestos, perlite, mica, phosphates, zeolites, clay, pumice, quartz, and silica, as well as elements such as sulphur, chlorine, and helium.

Lithosphere is the solid outermost shell of a rocky planet. On the Earth, the lithosphere includes the crust and the uppermost layer of the mantle (the upper mantle or lower lithosphere) which is joined to the crust.

As the cooling surface layer of the Earth's convection system, the lithosphere thickens over time. It is fragmented into relatively strong pieces, called tectonic plates, which move independently relative to one another. This movement of lithospheric plates is described as plate tectonics.

Mantle is the thick shell of dense rock surrounding the liquid metallic Earth's outer core, and lies directly beneath the Earth's thin crust. The term is also applied to the rocky shell surrounding the cores of other planets. Earth's mantle lies roughly between 30 and 2,900 km below the surface, and occupies about 70% of Earth's volume.

Cores of terrestrial planets tend to be mainly composed of iron and can include a solid and/or a liquid layer. Earth's core is partially liquid, whilst the core of Mars is thought to be completely liquid, due to its lack of an internally generated magnetic field for the last ~4 billion years. In our solar system, core size can range from almost nothing (the Moon) to 75% of the planets's radius (Mercury).

Soil science deals with soil as a natural resource on the surface of the earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils per se; and these properties in relation to the use and management of soils.

Sometimes terms which refer to branches of soil science, such as pedology (creation, chemistry, morphology and classification of soil) and edaphology (influence of soil on organisms, especially plants), are used as if synonymous with soil science. The diversity of names associated with this discipline is related to the various associations concerned. Indeed, engineers, agronomists, chemists, geologists, geographers, biologists, microbiologists, sylviculturists, sanitarians, archaeologists, and specialists in regional planning, all contribute to further knowledge of soils and the advancement of the soil sciences.

Pedosphere is the outermost layer of the Earth that is composed of soil and subject to soil formation processes. It exists at the interface of the lithosphere, atmosphere, hydrosphere and biosphere.

Oceanography, also called oceanology or marine science is the study of the Earth's oceans and seas. Oceanographers study a wide range of topics such as plate tectonics to ocean currents to marine organisms. These diverse topics reflect multiple disciplines that oceanographers blend to help us understand Earth's interdependencies: biology, chemistry, geology, meteorology, and physics.

Limnology is a discipline that concerns the study of inland waters (both saline and fresh), specifically lakes, ponds and rivers (both natural and manmade), including their biological, physical, chemical, and hydrological aspects. The term limnology stems from Greek limne (lake) and logos (study).

Hydrology, Hydrologia, the "study of water") is the study of the movement, distribution, and quality of water throughout the Earth, and thus addresses both the hydrologic cycle and water resources. A practitioner of hydrology is a hydrologist, working within the fields of either earth or environmental science, physical geography or civil and environmental engineering.

Domains of hydrology include hydrometeorology, surface hydrology, hydrogeology, drainage basin management and water quality, where water plays the central role. Oceanography and meteorology are not included because water is only one of many important aspects.

Hydrological research is useful in that it allows us to better understand the world in which we live, and also provides insight for environmental engineering, policy and planning.

Hydrosphere, in physical geography, describes the collective mass of water found on, under, and over the surface of a planet.

Atmospheric sciences is an umbrella term for the study of the atmosphere, its processes, the effects other systems have on the atmosphere, and the effects of the atmosphere on these other systems.

Meteorology includes atmospheric chemistry and atmospheric physics with a major focus on weather forecasting. Climatology is the study of atmospheric changes (both long and short-term) that define average climates and their change over time, due to both natural climate variability and anthropogenic climate variability or global warming.

Atmospheric science has been extended to the field of planetary science and the study of the atmospheres of the planets of the solar system.

Glaciology is the study of glaciers, or more generally the study of ice and natural phenomena that involve ice. The word glacier is derived from the Latin glacies, meaning ice or frost.

Glaciology is an interdisciplinary earth science that integrates geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. The impact of glaciers on humans adds the fields of Human geography and anthropology. The presence of ice on Mars and Europa brings in an extraterrestrial component to the field.

The term “cryosphere” traces its origins to the Greek word kryos for frost or icy cold. It collectively describes the portions of the Earth’s surface where water is in a solid form and includes sea ice, lake ice, river ice, snow cover, glaciers, ice caps and ice sheets, and frozen ground (which includes permafrost). The cryosphere is an integral part of the global climate system with important linkages and feedbacks generated through its influence on surface energy and moisture fluxes, clouds, precipitation, hydrology, and atmospheric and oceanic circulation. Through these feedback processes, the cryosphere plays a significant role in global climate and in climate model response to global change.