9. Glossary
Accelerator Mass Spectrometry (AMS) — counting atoms by accelerating ions in a sample to very high speeds and then separating the isotopes using powerful electric charges and magnets
Accuracy — one component of uncertainty, expresses how close a measurement comes to the true value
Acheulian biface — a technological complex of stone-tool manufacture characterised by distinctive oval and pear-shaped ‘handaxes’
Aeolian — deposits that are produced, carried, borne, deposited or eroded by the wind
Aliquot — an amount taken from a larger quantity
Alluvial — made up of or found in the materials deposited by running water, such as streams, rivers and flood waters
Ambient Magnetic Field — a vector field that describes the magnetic influence on electric currents, moving electric charges and magnetic materials
Amino acid — a simple organic compound containing both a carboxyl (-COOH) and an amino (-NH2) group
Aminostratigraphy — the measurement of the extent of amino acid racemisation in biological deposits, used to separate (and correlate) deposits into approximate time periods
Anglian — a glacial stage (MIS 12; c. 450,000 years ago) associated with a major Middle Pleistocene glaciation, during which ice sheets extended as far south as Oxfordshire and north London
Anteroconid Complex — a single dentine field with four large folds present within water vole teeth.
Archaeostratigraphy — identifies artefact types that are characteristic of certain technological stages, used to the separate (and to correlate) deposits into approximate time periods
Astrochronology — the dating of sedimentary units by calibration with astronomically tuned timescales, such as Croll–Milankovic cycles
Bayesian statistics — the branch of statistics in which evidence about the true state of the world is expressed in terms of degrees of belief
Bayes’ Theorem — an expression of the relationship between prior and current beliefs
Bifacial scraper — a lithic (stone) tool that has had flakes removed from both sides of the artefact
Biomineral — a mineral produced by the activity of living things
Bioturbation — the disturbance of sedimentary deposits by living organisms
Biostratigraphy — branch of stratigraphical analysis concerned with fossils and their use in dating sedimentary deposits
Boreal Zone — an ecosystem in the northern hemisphere with a subarctic climate, located between latitudes of 50° and 70°N
Breccia — a rock composed of large angular broken fragments of minerals or rocks cemented together by a fine-grained matrix
Brunhes chron — the final normal polarity chron in the Quaternary Period, preceded by the Matuyama chron, dated from 0.78 Ma to the present
Cenozoic — last era of the Phanerozoic Eon, beginning at the end of the Mesozoic Era at the end of Cretaceous Period, c. 65 Ma, and divided into three periods: Paleogene (c. 65–23 Ma), Neogene (c. 23–2.6 Ma) and Quaternary (c. 2.6 Ma to present)
Chron — an interval of geological time; in palaeomagnetism, this relates to the time interval between polarity reversals of Earth's magnetic field
Chronology — the science of arranging events in their order of occurrence in time
Chronostratigraphy — branch of geology concerned with establishing the absolute ages of strata
Clactonian — a stone tool industry typified by core and flake technology, within the main sites in England dating to early MIS 11 to early MIS 9
Clastic material — created when bedrock is weathered chemically or mechanically, and then transported away by erosion
Climatic optimum — period of highest prevailing temperatures within an interglacial
Climatostratigraphy — the division of Quaternary sedimentary sequences based on the recorded climatic signals within a deposit, such as the Marine Oxygen Isotope stages
Coleopteran — an insect of the order Coleoptera (a large family of insects including beetles and weevils)
Colluvial — sediments that accumulate at the base of a hillslope by rainwash, sheetwash, slow downslope creep, or a combination of these processes
Core and flake technology — stone tool-making technology characteristic of the Lower Palaeolithic, although it occurs in all periods of prehistory; it is defined by an absence of core preparation and the production of irregular flakes
Cosmic Dose Rate — the quantity of cosmic radiation received over a specific time
Cosmic ray — a highly energetic atomic nucleus or other particle travelling through space at nearly light speed
Cosmogenic isotopes (or nuclides) — produced by cosmic rays colliding with atoms in the atmosphere or on the surface of the Earth
Coversand — windblown periglacial aeolian deposits, consisting of fine- to very fine-grained sands
Coercivity — the resistance of a magnetic material to changes in magnetisation
Cretaceous — last period of the Mesozoic Era, starting at the end of the Jurassic Period c. 145 Ma and ending at the beginning of the Paleogene Period 65 Ma
Croll–Milankovitch cycle — describes orbital forcing through variations in the eccentricity, the axial tilt and the precession of the Earth's orbit and their effects on climatic patterns on Earth
Cromerian Complex — an Early-to-Mid Pleistocene stage in the NW Europe Quaternary climatostratigraphic scheme associated with MIS 21–13 (c. 866–478 ka)
Cromer Forest-bed Formation (sometimes known as the Cromer Forest Bed) — a geological formation in Norfolk and the type locality for the Cromerian Complex in Britain
Cryptotephra — volcanic ash layers invisible to the naked eye and usually consisting of shards less than 125µm in size
Curie temperature (Curie point) — on heating a material, the temperature above which it loses its ferromagnetic properties; the blocking temperature of a particular mineral is related to its Curie temperature but may be lower owing to such considerations as chemical impurities, crystal size and shape
Dansgaard–Oeschger cycles — describe rapid climate fluctuations that occurred during the last glacial (Devensian) period
Declination — the angle in the horizontal plane between the geographic north and the projection of the magnetisation vector on the horizontal plane (i.e. the direction of magnetic north); directions to the east of geographic north are in positive values, and those to the west are in negative values
(Post) Depositional Remanent Magnetisation (DRM) — a remanent magnetisation acquired during or shortly after sediment deposition; this is usually due to magnetic particles of sediment rotating to align their intrinsic magnetisations with the ambient field as they settle out of a relatively nonturbulent water solution. They then become locked into position by the weight of sediment settling above them
Detritus — loose material, such as rock fragments or organic particles, that results directly from disintegration of the primary deposit
Devensian — relating to or denoting the most recent Pleistocene glaciation in Britain, identified with the Weichselian of northern Europe
Diamicton — a poorly sorted type of sediment or sedimentary rock containing a wide range of clast sizes
Dip and strike — a measurement convention used to describe the plane orientation or attitude of a planar geologic feature. Strike refers to the line formed by the intersection of a horizontal plane and an inclined surface; dip is the angle between that horizontal plane and the tilted surface
Dipolar Geomagnetic Signal — a geomagnetic signal that relates to the Earth’s magnetism
Dose Rate measurements — the quantity of radiation received by a sample: alpha particles (α), beta particles (β), gamma rays (γ) and cosmic rays; measured to determine the Dose Rate (Ḋ)
Dosimeter — a device that measures exposure to radiation
Electron Probe Microanalyser (EPMA) — a microbeam instrument used primarily for the in situ non-destructive chemical analysis of minute solid samples
Enamel Differentiation Ratio (SDQ) — method based on differences in the thickness of enamel bordering distal and mesial faces of enamel prisms in the first lower molar (m1), observed in the fossil water vole (genus Arvicola)
Erratic boulder — a rock or boulder that differs from the surrounding rock and is believed to have been brought from a distance by glacial action
Flowstone — sheetlike deposit of calcite or other carbonate minerals, which forms when water flows down the walls or along the floors of a cave
Fluvial — of or found in a river
Foraminifera — single-celled, predominantly marine organisms with shells made of calcium carbonate (calcareous) or from tiny grains of sand stuck together (agglutinate)
Gamma spectrometry — a technique that measures the gamma radiation emitted during radioactive decay
Geological timescale — system of chronological dating that relates geological strata (stratigraphy) to time; the largest defined units of time are eons, which, in turn, are divided into eras, periods, epochs and ages/stages
Geomagnetic field — the Earth’s spontaneously generated magnetic field. Largely due to movements of electrically conductive material in the Earth’s molten outer core but with a smaller magnitude contribution from ionic movements in the upper atmosphere
Geomagnetic Polarity Time Scale (GPTS) — geomagnetic timescale constructed from an analysis of magnetic anomalies measured over the ocean basins and tying these anomalies to known and dated magnetic polarity reversals found on land
GISP2 — the second Greenland Ice Sheet Project
Glacial — interval of cold climate associated with larger glaciers and expansion of continental ice-sheets, coupled with lower global sea level
Glacial Maximum — period within a glacial when global ice sheets reach their greatest extent
Glaciation — the process or state of being covered by glaciers or ice sheets
Glacial valley — a valley U-shaped in section, formed by the erosive forces of a moving glacier
Glacially dammed lake — a body of water formed when a glacier blocks the flow of water
GRIP — the Greenland Ice Core Project
Half-life — the time required for half the atoms in a sample of radioactive material to decay
Handaxe — a usually large, general-purpose bifacial Palaeolithic stone tool, often oval or pear-shaped in form and characteristic of certain Lower Palaeolithic stone tool industries
Heinrich events — a natural phenomenon in which large armadas of icebergs break off from glaciers and traverse the North Atlantic
Highest Posterior Density intervals — a range in which a certain proportion (usually 95% or 68%) of the true values of a distribution will lie
Holocene — the second (and present) epoch within the Quaternary Period, starting c. 11.7 ka
Hominin — the group consisting of modern humans (Homo sapiens), extinct human species and all our immediate ancestors
Hoxnian — a warm interglacial period following the Anglian glaciation, equivalent to MIS 11 (c. 424–374 ka)
Ice sheet — a layer of ice covering an extensive tract of land for a long period of time
Igneous rock — a rock formed through the cooling and solification of magma or lava
Inclination — the angle between the magnetisation vector and the horizontal plane; magnetisations pointing downward have positive inclination values, and those pointing upward have negative values
Interglacial — an interval of warmer global average temperature lasting thousands of years that separates consecutive glacial periods
Interstadial — relating to a minor period of less cold climate during a glacial period
Intra-crystalline fraction — a fraction of proteins that are not removed after prolonged strong oxidation
Ipswichian — the last Pleistocene warm interglacial period, equivalent to MIS 5e (c. 124–119 ka)
Isochron — a line on a diagram or map connecting points relating to the same time or equal times
Isotope — one of two or more forms of an element differing from each other in the number of neutrons present
Kettle hole — a depression or hole formed by the melting of ice buried in an outwash plain formed by a retreating glacier
Lacustrine — relating to or associated with lakes
Laminated sands — a deposit made up of fine- to medium-grained sand with flat, parallel laminae that are a few grains thick
Laser Ablation Inductively Coupled Plasma Mass Spectrometry — an analytical technique that performs highly sensitive elemental and isotopic analysis directly on solid samples
Last Glacial Maximum — the most recent time during the Devensian glaciation when ice sheets reached their greatest extent in Britain, c. 26–20 ka
Levallois technology — stone tool technology characteristic of the early Middle Palaeolithic in Britain, defined by the careful preparation of cores to enable the production of flakes with particular sizes and shapes
Liquid Scintillation Spectrometry — a technique that counts the electrons emitted during radioactive decay
Loess — an unstratified wind-deposited sedimentary deposit consisting of silt-size grains that are loosely cemented by calcium carbonate
Marine Magnetic Anomaly Profiles — variation in the strength of the Earth’s magnetic field recorded in rocks on the spreading ocean floor. Marine magnetic anomalies are formed when magma rises at spreading ridges and cools below the Curie point
Marine Oxygen Isotope Stage — alternating warm and cool periods in the past climate of the Earth, deduced from oxygen isotope data from deep sea core samples
Markov Chain Monte Carlo (MCMC) — a class of algorithms for sampling from a probability distribution
Matuyama chron — the final reverse polarity chron in the Quaternary, following the Gauss chron and preceding the Brunhes chron, dated from to 2.58 to 0.78 Ma
Morphostratigraphy — a body of sediment that is identified primarily from the surface form it displays
Mousterian tradition — a technological complex of stone-tool manufacture primarily associated with Neanderthals in Europe; it largely defines the later part of the Middle Palaeolithic
Mutual Climatic Range method — a method for determining the past climate at a site by examining the tolerances of a range of species found there
Natural Remanent Magnetisations (NRM) — the remanence of a natural sample as first measured in the laboratory (before any partial demagnetisation). The term implies nothing about the origin of the remanence, which could be thermoremanence or depositional remanence etc.
NGRIP — the drilling site of the North Greenland Ice Core Project (NGRIP or NorthGRIP) near the centre of Greenland
Nuclide — a distinct kind of atom or nucleus characterised by a specific number of protons and neutrons
Operculum — an anatomical feature resembling a lid or a small door that opens and closes, controlling contact between the outside world and an internal part of an animal
Orbital tuning — the process of adjusting the time scale of a geologic or climate record so that the observed fluctuations correspond to the Croll–Milankovitch cycles (q.v.) in the Earth's orbital motion
Ostracods — small crustaceans found in various aquatic and terrestrial environments
Ovate bifaces — a lithic (stone) tool characterised by rounded edges and weak definition in shape to both the bottom (proximal) and top (distal) ends
Palaeolithic — the cultural period once referred to as the Old Stone Age. It is defined by the practice of hunting and gathering and the use of chipped flint tools. This period is usually divided up into:
- Lower Palaeolithic (pre c. 300 ka): the earliest subdivision of the Palaeolithic, or Old Stone Age, when hominins began to make and use the earliest flint tools found in the current archaeological record. These were Homo antecessor, Homo heidelbergensis and early Neanderthals;
- Middle Palaeolithic (c. 300–43 ka): the second subdivision of the Palaeolithic, or Old Stone Age, when Neanderthals began to manufacture and use stone tools using Levallois technology (q.v.) and the fine flake tools of the Mousterian tradition (q.v.);
- Upper Palaeolithic (c. 43–11.5 ka): the third and last subdivision of the Palaeolithic, or Old Stone Age, in which modern humans had evolved and arrived in Europe, and began to manufacture and use a variety of fine-blade flint tools from prepared cores and to make projectile points from bony materials.
Palaeointensity-Assisted Chronology (PAC) — the use of Relative Palaeointensity (RPI, q.v.) to constrain the chronology of a sedimentary sequence
Palaeosecular Variation (PSV) — short-period secular variations in both direction and magnitude, capable of providing decadal to millennial age resolutions
Palaeomagnetic polarity — the relative orientation of the Earth’s magnetic poles in the past
Palynology — the recovery and study of ancient pollen grains for the purposes of analysing ancient climate, vegetation and diet
Pedostratigraphy — the study of the stratigraphical and spatial relationships of surface and buried soils
Pedoturbation — the process by which a soil is physically mixed or disturbed
Pleistocene — the first epoch within the Quaternary Period, between c. 2.58 Ma and 11.7 ka
Pliocene — the last epoch of the Tertiary Period, between the Miocene and Pleistocene Epochs, between c. 5.3 and 2.6 Ma
Polarity — the relative orientation of magnetic poles
Post-glacial — relating to or occurring during the time following a glacial period, usually referring to the time after the Last Glacial Maximum (q.v.)
Posterior beliefs — our state of understanding a problem after considering new data
Posterior density estimate — a function that describes the likelihood of a date occurring at a particular point in time
Pretreatment — physical and chemical processing of a sample to purify it before combustion
Prior beliefs — our state of understanding a problem before considering new data
Precision — one component of uncertainty, indicating the degree to which measurements are repeatable and reproducible
Quaternary Period — the most recent period of the Cenozoic Era, starting c. 2.6 Ma. It follows the Tertiary Period and is subdivided into the Pleistocene and Holocene Epochs
Racemisation — the transformation of one-half of the molecules of an optically active compound into molecules that possess exactly the opposite (mirror-image) configuration
Radiocarbon calibration — the process of converting a radiocarbon measurement into a distribution, or range, of possible calendrical dates, expressed as cal BC or cal BP
Radioactive decay — the spontaneous distintegration of atoms by emission of matter and energy
Radioactivity — the emission of radiation from a radionuclide during radioactive decay
Radionuclide — an atom that has excess nuclear energy, making it unstable and subject to radioactive decay
Relative Palaeointensity (RPI) — the record of relative geomagnetic intensity variations measured from normalised natural remanent magnetisation of sedimentary samples. The normalisation is typically done by a laboratory-introduced magnetisation to compensate for the ability of the sample to acquire magnetisation
Sand reactivation — the act or process of making a previously fixed sand deposit active, or becoming active, again
Secondary Ion Mass Spectrometry (SIMS) — a technique for chemical analysis and imaging of solid materials
Solifluction — slow, downslope movement of fine-grained surface material owing to repeated freezing and thawing cycles
Speleothem — chemically-precipitated deposits that accumulate over time within cave environments
Stable isotope — an isotope that does not undergo radioactive decay
Stadial — a relatively cold period during a glacial period
Stage — the lowest ranking unit of time for a geological time scale (q.v.) that can be recognised on a global scale
Stratigraphy — study of the order and relative position of strata / archaeological deposits
Stratotype — designated exposure of a named layered stratigraphic unit or of a stratigraphic boundary that serves as the standard of reference (type site)
Student’s-t distribution — a statistical function that creates a probability distribution, similar to the normal distribution with its bell shape
Superconducting Rock Magnetometer — a technique for measuring the magnetic properties of samples
Taphonomy — the circumstances and processes of fossilisation
Tephra — fragments of rock that are produced when magma or rock is explosively ejected by a volcano
Tephrochronology — a method of age determination that uses discrete layers of tephra from a single eruption to create a chronological framework
Tertiary — the first period of the Cenozoic Era, between the Cretaceous and Quaternary Periods, c. 65–2.6 Ma
Thermal Remanent Magnetisation (TRM) — a remanent magnetisation acquired after a substance has been heated then cooled in an ambient magnetic field
Total Hydrolysable Amino Acid Fraction — a measure of all amino acids in a sample after they have been hydrolysed
Travertine — a sedimentary rock formed by the chemical precipitation of calcium carbonate minerals from fresh water, typically in springs rivers or lakes
Tufa — a sedimentary rock formed by the chemical precipitation of calcium carbonate minerals from fresh water, characterised by their large microbiological component and high porosity
Ultrafiltration — filtration using a medium fine screen mesh size, enough to retain colloidal particles, viruses or large molecules
Uranium-series — the radioactive decay chain where unstable heavy atomic nuclei decay through a sequence of alpha and beta decays until a stable nucleus is achieved. This sequence begins with 238U and ends with 206Pb. It is used to quantify dose rate in luminescence dating and in Electron Spin Resonance (ESR). Uranium-Thorium dating is based on part of the Uranium-series radioactive decay chain
Virtual Geomagnetic Pole (VGP) — a point on the Earth's surface at which a magnetic pole would be located if the observed direction of remanence at a particular location was due to a geocentric magnetic dipole field
Vitreous — like glass in appearance or physical properties
