Subsoil in the context of "Soil mapping"

In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant, microbial and animal matter. It is a kind of soil organic matter with distinct properties due to its high surface area. It is rich in nutrients and retains moisture in the soil, more especially in soils with a sandy texture. Humus is the Latin word for "earth" or "ground".

In agriculture, "humus" sometimes also is used to describe mature or natural compost extracted from a woodland or other spontaneous source for use as a soil conditioner. It is also used to describe a topsoil horizon that contains organic matter (humus type, humus form, or humus profile).

A compressed earth block (CEB), also known as a pressed earth block or a compressed soil block, is a building material made primarily from an appropriate mix of fairly dry inorganic subsoil, non-expansive clay, sand, and aggregate. Forming compressed earth blocks requires dampening, mechanically pressing at high pressure, and then drying the resulting material. If the blocks are stabilized with a chemical binder such as Portland cement they are called compressed stabilized earth block (CSEB) or stabilized earth block (SEB). Typically, around 3,000 psi (21 MPa) of pressure is applied in compression, and the original material volume is reduced by about half.

Creating CEBs differs from rammed earth in that the latter uses a larger formwork into which earth is poured and manually tamped down, creating larger forms such as a whole wall or more at one time, rather than building blocks. CEBs differ from mud bricks in that the latter are not compressed, but solidify through chemical changes that take place as they air dry. The compression strength of properly made CEB usually exceeds that of typical mud brick. Building standards have been developed for CEB.

Moorland or moor is a type of habitat found in upland areas in temperate grasslands, savannas, and shrublands and the biomes of montane grasslands and shrublands, characterised by low-growing vegetation on acidic soils. Moorland today generally means uncultivated hill land (such as Dartmoor in South West England), but also includes low-lying wetlands (such as Sedgemoor, also South West England). It is closely related to heath, although experts disagree on the exact distinction between these types of vegetation. Generally, moor refers to highland and high rainfall areas, while heath refers to lowland zones which are more likely to be the result of human activity.

Moorland habitats are found mainly in tropical Africa, northern and western Europe, and South America. Most of the world's moorlands are diverse ecosystems. In the extensive moorlands of the tropics, biodiversity can be extremely high. Moorland is also related to tundra (where the subsoil is permafrost or permanently frozen soil), appearing as the tundra and the natural tree zone. The boundary between tundra and moorland constantly shifts with climatic change.

A seismic source is a device that generates controlled seismic energy used to perform both reflection and refraction seismic surveys. A seismic source can be simple, such as dynamite, or it can use more sophisticated technology, such as a specialized air gun. Seismic sources can provide single pulses or continuous sweeps of energy, generating seismic waves, which travel through a medium such as water or layers of rocks. Some of the waves then reflect and refract and are recorded by receivers, such as geophones or hydrophones.

Seismic sources may be used to investigate shallow subsoil structure, for engineering site characterization, or to study deeper structures, either in the search for petroleum and mineral deposits, or to map subsurface faults or for other scientific investigations. The returning signals from the sources are detected by seismic sensors (geophones or hydrophones) in known locations relative to the position of the source. The recorded signals are then subjected to specialist processing and interpretation to yield comprehensible information about the subsurface.

Fill dirt (also called cleanfill, or just fill) is earthy material which is used to fill in a depression or hole in the ground or create mounds or otherwise artificially change the grade or elevation of real property.

Fill dirt is usually subsoil (soil from beneath topsoil) and underlying soil parent material which has little soil organic matter or biological activity. Fill dirt is taken from a location where soil is being removed as a part of leveling an area for construction; it may also contain sand, rocks, and stones, as well as earth. Fill dirt should be as free of organic matter as possible since organic matter will decompose creating pockets of empty space within the fill which could result in settling. Uneven or excessive settling of the fill can result in damage to any structures built on the fill.

A concrete slab is a common structural element of modern buildings, consisting of a flat, horizontal surface made of cast concrete. Steel-reinforced slabs, typically between 100 and 500 mm thick, are most often used to construct floors and ceilings, while thinner mud slabs may be used for exterior paving (see below).

In many domestic and industrial buildings, a thick concrete slab supported on foundations or directly on the subsoil, is used to construct the ground floor. These slabs are generally classified as ground-bearing or suspended. A slab is ground-bearing if it rests directly on the foundation, otherwise the slab is suspended. For multi-story buildings, there are several common slab designs (see § Design for more types):

The continental shelf of Russia or the Russian continental shelf is the continental shelf adjacent to the Russian Federation. Geologically, the extent of the shelf is defined as the entirety of the continental shelves adjacent to Russia's coasts. In international law, however, the United Nations Convention on the Law of the Sea more narrowly defines the extent of the shelf as the seabed and subsoil of the submarine areas over which a state exercises sovereign rights.

The Siberian Shelf in the Arctic Ocean is the largest (and least explored) of the Russian shelves, a region of strategic importance because of its oil and natural gas reserves. Other parts of the Russian shelf are typically named after the corresponding seas: Barents Shelf (Barents Sea Shelf), Chukchi Shelf (Chukchi Sea Shelf), etc. With the exception of internal Russian seas, these geological shelves are shared with other countries which share the corresponding seas. For example, the Chukchi Shelf is shared between Russia and the United States according to the 1990 USA-USSR maritime boundary.

The International Seabed Authority (ISA; French: Autorité internationale des fonds marins) is a Kingston, Jamaica-based intergovernmental body of 167 member states and the European Union. It was established under the 1982 UN Convention on the Law of the Sea (UNCLOS) and its 1994 Agreement on Implementation. The ISA's dual mission is to authorize and control the development of mineral related operations in the international seabed, which is considered the "common heritage of all mankind", and to protect the ecosystem of the seabed, ocean floor and subsoil in "The Area" beyond national jurisdiction. The ISA is responsible for safeguarding the international deep sea, defined as waters below 200 meters (656 feet), where photosynthesis is hampered by inadequate light. Governing approximately half of the total area of the world's oceans, the ISA oversees activities that might threaten biological diversity and harm the marine environment.

Since its inception in 1994, the ISA has approved over two dozen ocean floor mining exploration contracts in the Atlantic, Pacific and Indian Oceans. The majority of these contracts are for exploration in the Clarion–Clipperton zone between Hawaii and Mexico, where polymetallic nodules contain copper, cobalt and other minerals essential for powering electric batteries. To date, the Authority has not authorized any commercial mining contracts as it continues to deliberate over regulations amid global calls for a moratorium on deep sea mining. Scientists and environmentalists warn that such mining could wreak havoc on the ocean, a crucial carbon sink and home to rare and diverse species.

Soil compaction, also known as soil structure degradation, is the increase of bulk density or decrease in porosity of soil due to externally or internally applied loads. Compaction can adversely affect nearly all physical, chemical and biological properties and functions of soil. Together with soil erosion, it is regarded as the "costliest and most serious environmental problem caused by conventional agriculture."

In agriculture, soil compaction is a complex problem in which soil, crops, weather and machinery interact. External pressure due to the use of heavy machinery and inappropriate soil management can lead to the compaction of subsoil, creating impermeable layers within the soil that restrict water and nutrient cycles. This process can cause on-site effects such as reduced crop growth, yield and quality as well as off-site effects such as increased surface water run-off, soil erosion, greenhouse gas emissions, eutrophication, reduced groundwater recharge and a loss of biodiversity.