SpallationSpallation is a process in which fragments of material (spall) are ejected from a body due to impact or stress. In the context of impact mechanics it describes ejection of material from a target during impact by a projectile. In planetary physics, spallation describes meteoritic impacts on a planetary surface and the effects of stellar winds and cosmic rays on planetary atmospheres and surfaces. In the context of mining or geology, spallation can refer to pieces of rock breaking off a rock face due to the internal stresses in the rock; it commonly occurs on mine shaft walls.
Cosmogenic nuclideCosmogenic nuclides (or cosmogenic isotopes) are rare nuclides (isotopes) created when a high-energy cosmic ray interacts with the nucleus of an in situ Solar System atom, causing nucleons (protons and neutrons) to be expelled from the atom (see cosmic ray spallation). These nuclides are produced within Earth materials such as rocks or soil, in Earth's atmosphere, and in extraterrestrial items such as meteoroids. By measuring cosmogenic nuclides, scientists are able to gain insight into a range of geological and astronomical processes.
MoraineA moraine is any accumulation of unconsolidated debris (regolith and rock), sometimes referred to as glacial till, that occurs in both currently and formerly glaciated regions, and that has been previously carried along by a glacier or ice sheet. It may consist of partly rounded particles ranging in size from boulders (in which case it is often referred to as boulder clay) down to gravel and sand, in a groundmass of finely-divided clayey material sometimes called glacial flour.
Llanquihue glaciationThe last glacial period and its associated glaciation is known in southern Chile as the Llanquihue glaciation (Glaciación de Llanquihue). Its type area lies west of Llanquihue Lake where various drifts or end moraine systems belonging to the last glacial period have been identified. The glaciation is the last episode of existence of the Patagonian Ice Sheet. Around Nahuel Huapi Lake the equivalent glaciation is known as the Nahuel Huapi Drift. The preceding interglacial is known as the Valdivia interglacial after its type locality of Valdivia.
Snowball EarthThe Snowball Earth is a geohistorical hypothesis that proposes during one or more of Earth's icehouse climates, the planet's surface became entirely or nearly entirely frozen with no liquid oceanic or surface water exposed to the atmosphere. The most academically referred period of such global glaciation is believed to have occurred sometime before 650 mya during the Cryogenian period. Proponents of the hypothesis argue that it best explains sedimentary deposits that are generally believed to be of glacial origin at tropical palaeolatitudes and other enigmatic features in the geological record.
Terminal moraineA terminal moraine, also called an end moraine, is a type of moraine that forms at the terminal (edge) of a glacier, marking its maximum advance. At this point, debris that has accumulated by plucking and abrasion, has been pushed by the front edge of the ice, is driven no further and instead is deposited in an unsorted pile of sediment. Because the glacier acts very much like a conveyor belt, the longer it stays in one place, the greater the amount of material that will be deposited.
Altitude trainingAltitude training is the practice by some endurance athletes of training for several weeks at high altitude, preferably over above sea level, though more commonly at intermediate altitudes due to the shortage of suitable high-altitude locations. At intermediate altitudes, the air still contains approximately 20.9% oxygen, but the barometric pressure and thus the partial pressure of oxygen is reduced. Depending on the protocols used, the body may acclimate to the relative lack of oxygen in one or more ways such as increasing the mass of red blood cells and hemoglobin, or altering muscle metabolism.
Effects of high altitude on humansThe effects of high altitude on humans are mostly the consequences of reduced partial pressure of oxygen in the atmosphere. The oxygen saturation of hemoglobin determines the content of oxygen in blood. After the human body reaches around above sea level, the saturation of oxyhemoglobin begins to decrease rapidly. However, the human body has both short-term and long-term adaptations to altitude that allow it to partially compensate for the lack of oxygen.
PeriglaciationPeriglaciation (adjective: "periglacial", referring to places at the edges of glacial areas) describes geomorphic processes that result from seasonal thawing and freezing, very often in areas of permafrost. The meltwater may refreeze in ice wedges and other structures. "Periglacial" originally suggested an environment located on the margin of past glaciers. However, freeze and thaw cycles influence landscapes also outside areas of past glaciation. Therefore, periglacial environments are anywhere when freezing and thawing modify the landscape in a significant manner.
Chronological datingChronological dating, or simply dating, is the process of attributing to an object or event a date in the past, allowing such object or event to be located in a previously established chronology. This usually requires what is commonly known as a "dating method". Several dating methods exist, depending on different criteria and techniques, and some very well known examples of disciplines using such techniques are, for example, history, archaeology, geology, paleontology, astronomy and even forensic science, since in the latter it is sometimes necessary to investigate the moment in the past during which the death of a cadaver occurred.
