Earth Sciences Forum

Andre · Posted: Wed Jul 25, 2007 11:13 am Post subject: Glossary of terms

Apparently it is necessary to distinguish one group from another by using difficult unusual words, in order to be looking learned. I try to avoid that but it’s inevitable I guess, when one works with them on a daily basis. Moreover if you need to communicate with members of these groups one should use the difficult words to keep up the appearance. Therefore I created this sticky as reference for my ramblings. Note; Whenever the word “alleged” is included, then I have serious reasons to doubt the formal explanations.

A extensive glossary is here

I try to keep it to a single post but by all means post here with questions or with contributions and I will merge them here.

Bölling-Allerød an series of alleged warm climate events (Interstadials) between ~14,500 and 12,700 before present, interrupted by some brief alleged colder events, the Oldest Dryas and the Older Dryas.

Cal BP thousand radio carbon dated, calibrated to calendar years before present, present is 1950

Clathrate is a chemical substance consisting of a lattice of one type of molecule trapping and containing a second type of molecule. Most common form is methane hydrate, or methane ice an ice substance with a water cage constructions containing methane molecules.

d18O or δ18O ratio of heavy 18O isotopes to the normal 16O isotopes relative to a certain standard, See VSMOV unit is mil or permil (one thousandth)

Dansgaard Oeschger event Series of very rapid climate changes— allegedly up to 7 °C in some fifty years—during the Quaternary period, and especially during the most recent glacial cycle.

dD or δD or δ2H, ratio of heavy hydrogen 2H or Deuterium (D) Further same details as δ18O

Eemian last Interglacial approximately between 135,000 - 110,000 years ago, American: Sangamonian, UK: Ipwichian.

Facies: Term denoting sedimentary deposit of a particular character or origin such as deltaic facies, playa lake facies (dust)

GISP: Greenland Ice Sheet Project usually indicating the ice core records of the GISP-II Core, the US version.

GRIP: GReenland Ice core Project, indicating the ice core records of the GRIP ice Core, the European version

Heinrich events recovered rock masses on the sea floor of continental origin on a wide scale in the atlantic, suggest to have been delivered by armadas of ice bergs, once part of a clacier or ice sheet (Ice Rafted Detritus) which occurred several times during the last glacial period, or "ice age".

Isotope: One of two or more forms of a single element; the atoms of each isotope have the same number of protons but different numbers of neutrons in their nuclei. Thus isotopes have the same atomic number but differ in atomic mass.

Ka BP thousand radio carbon dated years before present present is 1950

Last Glacial Maximum period with lowest isotope values alleged the coldest part of the last stadial from about 23,000 years ago to 18,000 years ago.

Mystery Interval Period between the Last Glacial Maximum and the Bolling Allerod, sometimes erroneously indicated with Oldest Dryas or Periglacial.

MIS: Maritime Isotope Stage, numbered series of isotope extremes in the oceanic sediment records. The odd numbers are alleged warm, the even numbers alleged cold.

ODP: Ocean Drilling Program the recovery program of hundreds of sediment cores from the ocean floor for geologic research.

Pleistocene: The span of geological time preceding the Recent epoch of the Holocene The beginning of the epoch is subject to debate and ranges from 3-1,6 million years ago. The end is defined 10.000 (radiocarbon) years ago with the end of the last Ice Age.

Proxy: (geologic) measured data values or data value series from a chronological record, that allows for calculating or inferring another more useful variable, restricted to its assumptions. For instance the lenght of the column of fluid in a thermometer is a proxy for the temperature. δ18O in precipitation water is a combined proxy for temperature at condenstation (dewpoint) and amount of rain out of the cloud.

Tephra volcanic ash, air-fall material produced by a volcanic eruption in general of various composition or fragment size.

Tephrochronology is a geochronological technique identifying discrete layers of tephra from known eruptions with known dates for dating stratified layers.

Varve: A layer or series of layers of sediment deposited in a body of still water in one year. (Swedish)

VSMOV Vienna Standard Mean Ocean Water international standard for isotope ratios

WeichselianLast glacial stadial between about 110,000 - 11,600 years ago, American: Wisconsin glacial, UK: Devensian glacial

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Charley Brown

billiards · Posted: Wed Jul 25, 2007 11:37 am Post subject:

Nice contribution Andre. I think "Facie" should have an "s" on the end, i.e. it is normally (in English) written Facies.

The definition of Proxy is a little unclear, you need to add that a proxy is something that is measured and used to infer some other variable. For example, the electrical conductivity of water is a proxy for its salinity... or in climate science you might say that the delta¹⁸O ratio is a proxy for temperature.