What is Geoscience?
Earth science (also known as geoscience, the geosciences or the Earth Sciences), is an all-embracing term for the sciences related to the planet Earth. It is arguably a special case in planetary science, being the only known life-bearing planet. There are both reductionist and holistic approaches to Earth science. The major historic disciplines use physics, geology, geography, mathematics, chemistry, and biology to build a quantitative understanding of the principal areas or spheres of the Earth system.


Earth's Spheres
Earth System science generally recognizes 4 spheres, the lithosphere, the hydrosphere, the atmosphere, and the biosphere. These correspond to rocks, water, air, and life. Some practitioners include the crysophere (ice) as a distinct portion of the hydrosphere and the pedosphere (soil) as an active, intermixed sphere as part of Earth's spheres.


• Geology describes the rocky parts of the Earth's crust (or lithosphere) and its historic development. Major subdisciplines are mineralogy and petrology, geochemistry, geomorphology, paleontology, stratigraphy, engineering geology and sedimentology.

• Geodesy and Geophysics (joined together in the IUGG) investigate the figure of the Earth, its reaction to forces and its potential fields (magnetic and gravity field). Geophysicists explore also the Earth's core and mantle and the natural deposits, while geodesists study the movement of stars and satellites.

• Soil science covers the outermost layer of the Earth's crust that is subject to soil formation processes (or pedosphere). Major subdisciplines include edaphology and pedology.

• Oceanography and Hydrology (incl. Limnology) describe the marine and freshwater domains of the watery parts of the Earth (or hydrosphere). Major subdisciplines include hydrogeology and physical, chemical, and biological oceanography. Within the scientific union IUGG the disciplines are joined with Geophysics, except the chemical ones.

• Glaciology covers the icy parts of the Earth (or cryosphere)

• Atmospheric sciences cover the gaseous parts of the Earth (or atmosphere) between the surface and the exosphere (~1000 km). Major subdisciplines are Meteorology, Climatology and Aeronomy.

Due to the numerous interactions among the spheres, many modern fields take an interdisciplinary approach and thus do not sit comfortably in this scheme. Even the above cases do not operate in isolation. For example, to understand the circulation of the oceans, the interactions between ocean, atmosphere and Earth rotation must be considered.

Soil Science
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 (formation, 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.

In a balanced soil, plants grow in an active and vibrant environment. The mineral content of the soil and its physical structure are important for their well-being, but it is the life in the earth that powers its cycles and provides its fertility. Without the activities of soil organisms, organic materials would accumulate and litter the soil surface, and there would be no food for plants. The soil biota includes:
• Megafauna: size range 20 mm upwards, e.g. moles, rabbits, and rodents.
• Macrofauna: size range 2-20 mm, e.g. woodlice, spiders, earthworms, beetles, centipedes, slugs, snails, ants, and harvestmen.
• Mesofauna: size range 100 micrometre-2 mm, e.g. tardigrades, mites and springtails.
• Microfauna and Microflora: size range 1-100 micrometres, e.g. yeasts, bacteria, fungi, protozoa, roundworms, and rotifers.
Of these, bacteria and fungi play key roles in maintaining a healthy soil. They act as decomposers that break down organic materials to produce detritus and other breakdown products. Soil detritivores, like earthworms, ingest detritus and decompose it. Saprotrophs, well represented by fungi and bacteria, extract soiluble nutrients from detritus.

Altering soils to achieve new uses
• Vitrification to contain radioactive wastes
• Enhancing soil microbial capabilities in degrading contaminants (bioremediation).

Environmental Soil Science
Environmental soil science is the study of the interaction of humans with the pedosphere as well as critical aspects of the biosphere, the lithosphere, the hydrosphere, and the atmosphere. Environmental soil science addresses both the fundamental and applied aspects of the field including: buffers and surface water quality, vadose zone functions, septic drain field site assessment and function, land treatment of wastewater, stormwater, erosion control, soil contamination with metals and pesticides, remediation of contaminated soils, restoration of wetlands, soil degradation, nutrient management, movement of viruses and bacteria in soils and waters, bioremediation, application of molecular biology and genetic engineering to development of soil microbes that can degrade hazardous pollutants, land use, global warming, acid rain, and the study of anthropogenic soils, such as terra preta.