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Dendroclimatology
Dendroclimatology is the science of reconstructing past climate from the annual growth rings of trees, using ring width, wood density, and isotopes to estimate past temperature and precipitation.
Dengying Formation
Dengying Formation: terminal Ediacaran (551–541 Ma) dolomite unit on the Yangtze platform, South China, with four members, microbialite fossil Lagerstätten, and giant Sichuan Basin gas reservoirs.
Denudation
Denudation, from the Latin denudare meaning "to lay bare," is the total lowering of the land surface by weathering and erosion acting together, and is broader than erosion alone.
Denver–Julesburg Basin
The Denver–Julesburg Basin, shortened to DJ Basin and also called the Denver Basin, is a Laramide-age petroleum basin underlying eastern Colorado, Wyoming, Nebraska, and Kansas.
Depositional sequence
A depositional sequence is a relatively conformable succession of genetically related strata bounded by unconformities, recording one cycle of relative sea-level change and serving as the fundamental unit of sequence stratigraphy.
Depth hoar
Depth hoar, also called sugar snow, is a layer of weak, cup-shaped ice crystals that forms at the base of the snowpack and drives persistent slab avalanches.
Depth sounding
Depth sounding is the measurement of water depth, historically by weighted lead line and today mostly by timing sound or laser pulses from the seafloor.
Derecho
A derecho is a widespread, long-lived windstorm produced by a band of rapidly moving thunderstorms, causing straight-line wind damage along paths hundreds of miles long.
Desert climate
A desert climate, also called an arid climate, is one where potential evapotranspiration exceeds annual precipitation, divided by the Köppen-Geiger system into hot desert (BWh) and cold desert (BWk).
Desert pavement
A desert pavement is a natural surface covering of closely packed, interlocking rock fragments over fine-grained sediment in arid regions, formed largely as wind-blown dust accumulates beneath the stones.
Desertification
Desertification, or desertization, is land degradation in arid, semi-arid, and dry sub-humid areas driven by climate change and human activities like overgrazing and deforestation, formalized in the 1994 UNCCD.
Desertification in the Sahel
Desertification in the Sahel is land degradation in the semi-arid belt south of the Sahara, the world's emblematic desertification case after the droughts and famines of the 1970s and 1980s.
Destratification
Destratification is the artificial mixing of a thermally stratified lake or reservoir, usually by injecting compressed air, to make temperature and dissolved oxygen roughly uniform throughout.
Detachment fault
A detachment fault is a large, gently dipping normal fault along which the upper crust slides away during extension, exposing deeper rocks in metamorphic core complexes.
Detection and attribution
Detection and attribution (D&A) is the climate science framework for showing whether observed climate change exceeds natural variability and how much is caused by greenhouse gases.
Detection and Attribution Model Intercomparison Project
The Detection and Attribution Model Intercomparison Project (DAMIP) is a CMIP6 climate model project separating the effects of greenhouse gases, aerosols, solar activity, and volcanism.
Detour Lake
Detour Lake is a large open-pit gold mine in Cochrane District, northeastern Ontario, near the Quebec border. Operated by Agnico Eagle, it is the largest gold-producing mine in Canada.
Detrital zircon geochronology
Detrital zircon geochronology measures uranium-lead ages of individual zircon grains separated from sedimentary rocks, identifying sediment sources, correlating successions, and limiting the age of deposition.
Deuterium excess
Deuterium excess, or d-excess, is a parameter in stable water isotope analysis, defined by Dansgaard in 1964, that measures deviation from the global meteoric water line.
Deutscher Wetterdienst
The Deutscher Wetterdienst (DWD) is Germany's national meteorological service, founded in 1952 and based in Offenbach am Main, issuing official severe-weather warnings for the country.
Devil's Throat, Iguazu Falls
The Devil's Throat (Spanish: Garganta del Diablo; Portuguese: Garganta do Diabo) is the largest and tallest cataract of Iguazu Falls, where the Iguazu River plunges about 80 meters into a U-shaped chasm on the Argentina–Brazil border.
Devonian
The Devonian, or Age of Fishes, is a geologic period from 419.2 to 358.9 million years ago, when jawed fishes dominated and the first tetrapods appeared.
Dew point
The dew point is the temperature to which air must be cooled at constant pressure for water vapor to condense, and a direct measure of humidity.
Dhamar, Harras of
Harras of Dhamar, a volcanic field in central-western Yemen near Dhamar city (14.57°N, 44.67°E), elevation 3,500 m, extending 80 km east with stratovolcanoes, cones, and a possible unconfirmed 1937 eruption.
Diagenesis
Diagenesis is the set of physical, chemical, and biological changes that convert deposited sediment into sedimentary rock at low temperatures and pressures, before metamorphism begins.
Diamictite
Diamictite is a lithified, poorly sorted siliciclastic sedimentary rock with a wide clast size range and no fixed origin; its widespread deposits record ancient glaciations such as the Cryogenian Snowball Earth episodes.
Diamond
Diamond is a mineral of crystallized elemental carbon, prized as a gemstone and used industrially; it forms deep in the mantle and is the hardest known natural material.
Diamond (gemstone)
Diamond is a gemstone cut from the mineral diamond, a pure form of carbon that is the hardest known natural material and the world's most popular gemstone.
Diamond clarity
Diamond clarity is one of the 4Cs of diamond grading, measuring the absence of internal inclusions and surface blemishes on a GIA scale from Flawless to I3.
Diamond color
Diamond color is the gem-trade grade of how little yellow or brown tint a diamond shows, graded D (colorless) to Z on the GIA scale.