For the Student

Glossary

A

Absolute dating
Back to the top

dates determined by methods whose accuracy is based on radioactive decay or regular natural phenomena such as tree rings or varves, or by secure historical evidence.

Aerial archaeology

reconnaissance and remote sensing conducted from aeroplanes, balloons or satellites.

AMS (accelerator mass spectrometry)

a radiocarbon dating method that measures the concentration of 14C isotopes rather than counting their radioactive decay.

Anaerobic:

preservation conditions where there is an absence of oxygen (for example in peat bogs) that leads to a slowing of the decay process.

Anatomically modern humans:

the most recent form of hominin, who appear to have evolved in Africa by 100,000 years ago and to have colonised the world since then, displacing earlier humans such as Neanderthals.

Anthropogenic:

effects caused by human actions as opposed to natural biological or geological forces.

Anthropology:

the study of humankind, including physical evolution, social systems and material culture.

Antiquaries, antiquarianism:

the fieldworkers and collectors who studied ancient sites and artefacts before rigorous methods of excavation and interpretation were developed in the nineteenth century.

Archaeological Data Service (ADS):

an online searchable database of electronic archives from projects in the UK, or run by organisations based there; see also OASIS.

Archaeomagnetism:

magnetic properties of artefacts and soils caused by human activities (especially those that involved burning); these properties may be exploited for archaeomagnetic dating of hearths and kilns and for remote sensing (magnetometer surveys and magnetic susceptibility surveys).

Artefact:

an object made or modified for use by humans.

Assemblage:

a group of artefacts found together in a single context such as a grave or hoard.

Associations:

artefacts or other items found together in the same layer or context.

B

Back to the top

Biosphere:

the ‘Earth's’ living organisms.

Bronze Age:

the second of the Three Ages defined by Thomsen in the early nineteenth century, characterised by the use of artefacts made from copper and copper alloys

C

Back to the top

Caesium magnetometer:

a very sensitive magnetometer allowing measurement of much smaller variations in the subsoil than a gradiometer.

Calibration:

correction of measurements to eliminate errors, notably in the case of the calibration curve derived from tree rings used to convert radiocarbon age estimations into calendar years.

Chalcolithic:

the copper age, between the Neolithic and Bronze Age, which occurs in some areas of Europe (for example Iberia).

Characterisation:

definition by scientific analysis of the distinctive minerals, elements or isotopes characteristic of specific sources of raw material such as quarries.

Chronology:

the establishment of relative or absolute dating systems.

Chronometric dating:

absolute dating based upon regular and measurable ‘clocks’ such as the rate of decay of radioactive isotopes.

Civilisation:

a loose term normally associated with societies living in towns using a writing system, such as Mesopotamia, Egypt or Shang dynasty China.

Classical archaeology:

the study of Greek and Roman sites and material culture.

Climatostratigraphy:

the use of environmental data from seabed cores, ice cores, varves and so on to establish and date climatic phases, notably ice ages.

Commensality:

the process of eating as a group, and feasting; regarded by many archaeologists and anthropologists as a key social process in societies.

Conservation:

in general, the preservation and care of ancient sites and landscapes; more specifically, laboratory techniques for stabilising objects or structures and preventing further decay.

Context:

a neutral term for any deposit or structure recorded during an excavation; sometimes described as ‘unit of stratification’.

Coprolites:

solid excreta from humans or animals preserved in arid or waterlogged conditions from which fragments of foodstuffs can be extracted to study ancient diets.

Crannog:

a raised settlement situated in a wetland location (usually a lake) found in Ireland, Scotland and Wales, dating from the first millennium bc to the first millennium ad.

Cremation:

disposal of the dead through burning at high temperatures. Frequently, in many times and regions, the remaining burnt bones were interred in pits or vessels.

Cross-dating:

the use of artefacts of known date to establish the age of undated contexts or assemblages in which they have been found; this dating may be extended to other artefacts found in association with them. It should be remembered that a dated artefact only provides a terminus post quem for the context in which it is found.

Cultural resource management (CRM):

the protection and conservation of archaeological and historic sites and landscapes; cultural resources are more commonly known as ‘heritage’ outside North America.

Cultures:

in the ‘culture history’ approach to archaeological interpretation that was popular in the first half of the twentieth century, recurrent associations of distinctive sites and artefacts that suggested a repeated pattern of human behaviour were described as cultures. Such patterns of material culture were frequently equated with tribes or other groups of people — even races.

D

Back to the top

Debitage:

the waste from the production of lithics. Has been used to reconstruct the ways in which stone tools were made.

Dendrochronology (tree-ring dating):

dating large samples of wood by matching the pattern of annual rings to a dated reference sequence; the final ring provides a terminus post quem for the cutting of the tree and for any structure or artefact made from its wood.

Diffusionism:

the idea, strongly associated with the culture history approach, that all cultural and technological developments in Europe spread from the civilisations of the Near East and Egypt.

Digital terrain model (DTM):

computer generated topography used for modelling archaeological landscapes; it is particularly effective for intervisibility studies, which reveal how many other sites can be seen from any chosen site, or for visualising past landscapes without the clutter of later features.

DNA:

the material in living organisms that carries genetic information.

Domestication:

systematic exploitation and selective breeding of plants and animals by means of agriculture and herding, begun by Neolithic communities in the Near East.

E

Back to the top

Ecofact:

natural and environmental evidence that relates to human activity, as opposed to an artefact, which is an object made or modified by humans.

Ecology:

the interaction of living organisms; in an archaeological context, the relationship between humans and their natural environment.

EDXRF (Energy-dispersive x-ray fluorescence):

the bombardment of an object with x-rays and measurement of the energy of secondary (fluorescent) x-rays. Distinctive wavelengths indicate the presence of different elements in the object. The ED-XRF technique allows more precise separation of wavelengths than other x-ray methods, permitting the measurement of smaller amounts of individual elements. It is also non-destructive, and has become a common way of analysing the composition of archaeological materials, especially metals.

Electronic distance measurement (EDM):

surveying equipment using laser or infra-red beams for high-precision measurement over long distances.

Enlightenment:

the eighteenth-century ‘Age of Reason’ in science and philosophy that followed the Scientific Revolution of the previous century.

Environmental archaeology:

general term for approaches to the interaction between humans and their biological and physical environment, ranging from general climatic factors to specific foodstuffs, and from landscapes to excavated soils.

Ethnicity:

the study of biological or cultural aspects of racial identity; closely related to culture history and diffusionism in the first half of the twentieth century. Attempts to trace the origins of modern populations through DNA studies have generated new interest in ethnicity.

Ethnoarchaeology:

ethnographic study of contemporary peoples, with a focus on material culture and the formation processes that create archaeological deposits. See also middle range theory.

Ethnography:

the anthropological study of contemporary cultures.

Evolution:

theories of biological and social development through the selection of advantageous characteristics, associated with Darwin and Spencer in the mid-nineteenth century ad.

Excarnation:

treatment of the dead through exposure to the elements and/or scavenging animals. May have taken place on designated platforms or by placing bodies in trees etc.

Experimental archaeology:

simulation and/or replication of ancient activities, structures and artefacts to study their performance, ideally with carefully designed scientific observation and controls.

F

Back to the top

Field archaeology, fieldwork:

non-intrusive methods of observing, surveying and documenting surface traces of sites without engaging in excavation.

Field survey:

multi-disciplinary study of the long-term settlement history of a region and its environmental setting; closely related to landscape archaeology.

Fieldwalking:

systematic observation of the ground surface during fieldwork, and especially the recovery of artefacts that may indicate periods of occupation.

Formation processes (taphonomy):

the circumstances in which archaeological sites are created by human activities and subsequently modified by decay, erosion and other natural processes.

G

Back to the top

Gender:

issues surrounding the identity and behaviour of men and women in the past and the ways in which they may be represented in archaeological terms, for example through different burial practices or the layout of settlements and buildings.

Geophysical surveying instruments:

a range of equipment designed to locate and record buried sites by measuring the electrical resistance, magnetism or other physical properties of the soil. The principal forms are resistivity meters, magnetometers and ground penetrating radar (GPR).

GIS: (Geographical Information System(s)):

a range of techniques using the graphic capabilities of powerful computers for an integrated analysis of maps, images, sites and finds. GIS has rapidly become essential in the interpretation of fieldwork data.

Glacials and interglacials:

the succession of Ice Ages alternating with temperate conditions established from evidence of changes in the natural and physical environment; see climatostratigraphy.

Grave goods:

a selection of personal items placed in a burial, perhaps as gifts to take into an afterlife or as an indication of the deceased's sex, social status and religion.

Grey literature:

a term often used by archaeologists in Britain to describe unpublished reports from excavations and investigations produced by commercial archaeologists. Most of these are only found in archives, making access to the results of this work more difficult than to published reports; see also ADS, OASIS.

Grubenhäuse:

an early medieval type of building in which a rectangular pit and associated post holes provide evidence for a wooden structure which may have had a sunken or suspended floor. It is a distinctive element of Anglo-Saxon settlement sites in England

H

Back to the top

Half-life:

the time taken for half of the radioactive isotopes (for example radiocarbon) in a sample to decay. The half-life may be used to estimate the age of a sample by measuring the amount of radioactivity that remains.

Henge monument:

a form of ritual enclosure, found mainly in Neolithic Britain, characterised by having a ditch inside its enclosing bank; burials, standing stones or settings for large timbers may be found in the interior (notably at Stonehenge).

Heritage:

a term (equivalent to the American ‘cultural resources’) that loosely describes those aspects of the past that survive today in physical form, from landscapes to structures and artefacts; its management and commercial aspects such as tourism are sometimes referred to as ‘the heritage industry’.

Historical archaeology:

in contrast to prehistory, the practice of archaeology in periods when written evidence is available; subdisciplines include Classical, medieval and industrial archaeology.

Historiography:

the study of ways of writing about the past, and their development over time under a variety of cultural and philosophical influences. Recent theoretical developments in archaeology have stressed the need to examine our own discipline more critically, and to analyse its structure and ways of thinking.

Hoard:

a collection of artefacts buried together at the same time (and therefore associated), for example coins and jewellery concealed during a period of insecurity.

Hominins:

the group of creatures that can be categorised as related to humans (Homo sapiens). Although the term is often used interchangeably with hominid or human ancestor, there are important differences between these terms. Hominins include all ape-like creatures, which can then be split into two groups on the basis of DNA: Ponginae (orang-utans) and Homininae (humans, human-like ancestors, chimpanzees, gorillas etc.). It is worth noting that the term ‘human ancestor’ is not always appropriate, as some hominins (such as Homo floresiensis) may not be directly related to modern humans (Homo sapiens).

Hunter-gatherers :

people who subsist on wild animals and plants, in contrast to settled Neolithic farmers or pastoralists supported by domesticated plants and animals.

I

Back to the top

Ice cores:

cylindrical samples extracted from the polar ice sheets, from which annual variations in temperature, snowfall and atmospheric chemistry may be detected.

Inhumation:

the burial of a body within a grave, pit or tomb.

Institute for Archaeologists (formerly the Institute of Field Archaeologists):

an organisation of professional archaeologists in the UK. Its Registered Organisations scheme for contract archaeology organisations aims to maintain the quality of archaeological standards. It also provides guidelines on best practice in various areas of field archaeology.

Interpretive archaeology:

an assortment of theoretical approaches associated with postprocessual archaeology and favouring ideas about individual experience rather than general processes.

Iron Age:

the third of Thomsen's Three Ages, characterised by iron technology.

Isotopes:

atoms with different numbers of neutrons in their nuclei but similar chemical properties. Unstable isotopes decay to form a different element, and are fundamental to several radiometric dating techniques including radiocarbon, potassium-argon and uranium series. Stable isotopes can be used in characterisation studies of raw materials and for detecting variations in diet from bones.

L

Back to the top

Landscape archaeology:

placing sites into a wider context using a full range of archaeological, environmental and historical information to interpret them on a regional basis on a long timescale. The techniques involved are also known as field survey.

LiDAR (Light Detection and Ranging):

a pulsed laser beam from an aircraft scans a survey area from side to side, building up an accurate, high resolution model of the ground surface. It is particularly good at recording insubstantial earthworks, and revealing features beneath plant foliage invisible to conventional aerial photography.

Lithics:

any form of stone tool, frequently made from flint

M

Back to the top

Magnetic dating, magnetic surveying, magnetometers:

see archaeomagnetism.

Material culture:

the range of physical evidence that may be observed by archaeologists and anthropologists, from artefacts to structures.

Megaliths:

structures built from very large stones, frequently ritual sites such as stone circles and chambered tombs. Although found throughout the world at different times, megaliths are particularly numerous in Neolithic and Bronze Age Europe.

Mesolithic:

transitional stage between the Palaeolithic (Old Stone Age) and Neolithic (New Stone Age) characterised by hunter-gatherers who used tools made up of multiple small stone blades (microliths).

Metallurgy, metallurgical analysis:

the study of metal ores, artefacts and waste products from processing (for example slag) to investigate their raw materials and technology.

Midden:

deposit of waste material, commonly composed of domestic and food waste. Shell-middens left by seasonal hunter-gatherers are common in coastal areas in many parts of the world.

Middle Range Theory:

an attempt to bridge the gap between fragmentary evidence of prehistoric sites and structures and modern ethnoarchaeological observations of how archaeological sites reflect human activities and behaviour.

Multivocality:

literally ‘many voices’. It is recognised in postprocessual archaeology that different groups and individuals have a variety of views about the past, according to their particular context and history. Thus multivocality helps to reduce the dominance of colonialist and Western interpretations. It also acknowledges that individuals in the past held many different views and underwent varying experiences; see also agency.

N

Back to the top

National Mapping Programme (NMP):

the plotting and mapping of oblique aerial photographs of archaeological features in England to provide a comprehensive database and GIS of archaeological cropmarks for research and heritage-management purposes.

National Trust:

a non-governmental charitable organisation established in 1895 to preserve and protect countryside, landscapes and historic monuments in England, Wales and Northern Ireland.

Neanderthals:

humans who occupied Europe and western Asia for a considerable period until they were displaced by anatomically modern humans between 100,000 and 30,000 years ago.

Neolithic:

‘New Stone Age’, characterised by communities farming domesticated plants and animals but still using stone tools, notably axes with a ground or polished rather than flaked surface. The Mesolithic to Neolithic transition is sometimes called the Neolithic Revolution or Agricultural Revolution.

New Archaeology:

movement (also known as processualism) that emerged in the United States in the 1960s using a scientific approach to archaeological questions by designing models, suggesting hypotheses and testing them in the hope of establishing laws governing human behaviour.

Noble Savage myth:

a philosophical and literary concept of the virtues of primitive life especially popular in the eighteenth century.

O

Back to the top
OASIS (Online AccesS to the Index of archaeological investigationS):

an index of archaeological investigations in Scotland and England hosted by the ADS. Online archiving means that more excavation and project data, much of it unpublished, is accessible to a wider audience; see also ADS, grey literature.

Obsidian:

a natural volcanic glass used for making flaked tools in many parts of the world; the obsidian hydration dating technique, in which relative age is estimated by the depth of weathering of its surface, may be applied to it.

Olduvai Gorge:

an important locality in northern Tanzania where erosion of the Rift Valley has exposed many geological strata containing human remains and artefacts, including the earliest ‘Oldowan’ chipped pebble tools.

Open-area excavation:

the uncovering of large continuous areas, in contrast to the box trench system developed by Mortimer Wheeler.

P

Back to the top

Palaeo-, paleo-:

prefix indicating ‘ancient’ attached to many natural and biological sciences (e.g. palaeoenvironment, paleosols (soils), paleodemography (population), palaeodiet, palaeo-botany (plants)).

Palaeodemography:

the study of the age and sex structures of past populations, usually by examining skeletal remains from archaeological contexts.

Palaeolithic:

the earliest of three subdivisions of the Stone Age, preceding the Mesolithic and Neolithic. It lasted several million years, from the first appearance of stone tools to the Mesolithic microlith-using hunter-gatherers of the most recent postglacial period, and is normally divided into Upper, Middle and Lower phases.

Palaeomagnetism:

natural magnetic properties of geological rocks and sediments, whose alignment underwent periods of north?south reversal that are important in geochronology and climatostratigraphy. Palaeomagnetism should be distinguished from archaeomagnetism, which is generated by human activities, notably the heating of materials made from clay by fire.

Palimpsest:

a term (adopted from the study of old manuscripts) used in archaeology to describe a landscape or a building that exhibits features and activities which accumulated over a long period. Features identifiable on an archaeological survey or geophysical plot are more likely to be a palimpsest rather than contemporary with each other.

Palynology:

identification of pollen grains recovered from samples of soil from archaeological sites, peat bogs or lake beds, and the reconstruction of ancient environments and climatic phases from the species present.

Paradigm shift:

a general change in outlook resulting from an accumulation of evidence undermining prevailing views. This phenomenon was identified in the sciences by Thomas Kuhn, but the term is frequently applied to wider intellectual movements.

Planning Policy Guidance (PPG) notes 15 and 16:

government guidance on the role of archaeology in planning for development in England. PPG15 (1994) concerns the preservation and protection of historic buildings whilst PPG16 (1990) relates only to buried remains. Equivalent documents exist in Scotland (NPPG5) and Wales. The guidance is currently being reviewed and is likely to be replaced by Planning Policy Statement (PPS) 15.

Portable Antiquities Scheme (PAS):

a voluntary scheme for the recording of archaeological objects found by metal-detector users in England and Wales. It is currently overseen by the British Museum but makes use of regional finds-liaison officers.

Positivism:

approach to science and human society developed in the nineteenth century, characterised by the replacement of speculation by propositions that may be tested to establish laws; New Archaeology has been criticised for having an excessively positivist approach.

Postprocessual archaeology:

a reaction to processualism (New Archaeology) avoiding positivism in favour of more recent anthropological approaches, such as symbolism and the role of material culture in social relationships. The term ‘interpretive archaeology’ is preferred by many archaeologists who have drawn upon a wider range of philosophical approaches from the 1990s onwards.

Potassium-argon dating:

an absolute technique based on the decay of a radioactive isotope of potassium, especially important in dating geologically recent volcanic deposits associated with early hominin remains in East Africa.

Prehistory:

the period — undocumented in historical sources — revealed by archaeological methods and interpreted with the help of anthropological and historical analogies.

Processualism:

see New Archaeology.

Pseudo-archaeology:

the practice of providing interpretations about the past that appear to use archaeological techniques but in reality ignore the critical and scientific approaches of archaeology. Defined and criticised in G. Fagan (2006).

R

Back to the top

Radioactive decay:

the release of particles by unstable isotopes at a constant rate; fundamental to radiometric dating methods such as radio-carbon and potassium-argon.

Radiocarbon dating:

the most important radiometric technique for dating later prehistory because of the short half-life of 14C, a radioactive isotope of carbon that is absorbed by all living things until their death. This allows the age of organic materials such as wood or bone to be estimated and converted to calendar years with the help of a calibration curve established from tree rings.

Radiometric dating:

methods measuring the decay of radioactive isotopes.

Register of Professional Archaeologists:

a voluntary listing of archaeologists in the USA who have agreed to abide by a code of conduct and professional standards, similar to those of the Institute for Archaeologists in Britain.

Relative dating:

relative ages (also known as derivative ages) established from methods such as obsidian hydration or archaeomagnetism cannot be used on their own but must be related to an absolute technique such as radiocarbon. Sequences of contexts established by the stratification of archaeological sites, or artefacts arranged into order by typology, are also relative unless fixed points can be established by cross-dating or association.

Remote sensing:

the use of aerial or satellite reconnaissance and photography to discover and interpret archaeological sites and landscape features, whether visible on the surface or buried, and the use on the ground of geophysical instruments to locate buried sites.

Renaissance:

a period of revival of interest in Classical Greek and Roman art, architecture and literature, especially in fifteenth-century Italy, which spread to the rest of Europe and (in combination with the Scientific Revolution) formed the basis for the Enlightenment of the eighteenth century.

Rescue archaeology:

archaeological fieldwork and/or excavation prompted by threats from development such as a road-building: an important component of cultural resource (or heritage) management.

Resistivity surveying:

geophysical technique based upon the extent to which buried soils and features resist the passage of an electric current.

Romanticism:

a reaction (primarily in the nineteenth century) against the rationality of the Enlightenment and the effects of the Industrial Revolution, commonly expressed in admiration for wild landscapes, primitive peoples and pre-Renaissance ‘Gothic’ architecture.

S

Back to the top

Seabed cores:

records of long-term climatic and environmental change recovered from sediments that accumulated continuously on the seabed. When correlated with reversals of the Earth's magnetic field (dated by potassium-argon), and calibrated by regular variations in the Earth's orbit, long-term changes in climate can be observed and dated (climatostratigraphy).

Sections:

vertical records of stratigraphy revealed by excavation and recorded in drawings and photographs as evidence of the sequence of contexts on a site.

Site formation:

see formation processes.

Social evolution, sociocultural evolution:

a belief that human societies developed increasing complexity over time (found in the writings of Lewis Henry Morgan, Karl Marx and Benjamin Kidd). It was reinforced in the nineteenth century by analogies from biological evolution. Many twentieth-century anthropologists and archaeologists rejected the idea of linear social evolution because it oversimplified the complexity of the past and underestimated the sophistication of many past and present societies.

Social evolution:

theories about the progression of human societies through stages, such as savagery, barbarism and civilisation; closely related to the biological and political thinking of Darwin and Marx.

Stratification, stratigraphy:

by analogy with geological strata, deposits on archaeological sites may be arranged in a sequence (with the earliest at the bottom) that may be dated with the help of any diagnostic artefacts they contain.

Structured deposition:

patterns of artefacts found in archaeological contexts suggesting that they were not deposited at random but were structured by human actions, such as ritual practices governing the burial of objects as votive offerings. Anthropological studies and recent theoretical perspectives indicate that even the disposal of rubbish may reflect belief systems and ‘ways-of-seeing’ in the past. Structured deposition has been identified in many Neolithic and Iron Age contexts in Britain and it has frequently been related to the concept of habitus.

T

Back to the top
Taphonomy:

see formation processes.

Taxonomy:

the scientific division and classification of animals and plants, developed as part of the Enlightenment desire to understand the natural ordering of organisms, and subsequently extended to archaeological objects.

Tell:

a large moundlike site common in the Near East, formed by the accumulation of occupation debris (especially mudbrick) over long periods.

Terminus ante quem, terminus post quem:

reference points in the dating of a stratigraphic sequence on a site before which (ante) or after which (post) a context was formed. One famous terminus ante quem is the volcanic deposit that destroyed Pompeii in ad 79, sealing earlier levels beneath it; a coin, dated to ad 15 and buried in foundations, is a terminus post quem for a building's construction.

Thermoluminescence dating (TL):

a method of determining absolute dates for fired clay or burnt stone; optically stimulated luminescence may be applied to unburned sediments that have been exposed to direct sunlight.

Thiessen polygon:

a model used in geography to define territories under the influence of ‘central places’ (usually towns). In archaeology, lines have been drawn equidistant between Neolithic long barrows, Iron Age hillforts and Mayan cities to define hypothetical ‘territories’. Models of this kind were extremely popular with exponents of New Archaeology, but they have been strongly criticised because known territorial boundaries rarely follow such simple rules.

Three-Age System:

Christian Thomsen's method of organising displays in the National Museum, Copenhagen, in 1819, based on the idea of technological progression from stone to metals and validated by associations between artefacts made from different materials in prehistoric graves.

Total Station:

a combination of a theodolite, electronic distance measurer (EDM) and electronic data recorder, frequently used to conduct topographic surveys or to record the precise location of excavations and geophysical surveys.

Treasure Act:

passed in 1996 and effecting England, Wales and Northern Ireland. It replaced Treasure Trove. Which items should be defined as treasure is somewhat complex, but they include object at least 300 years old (when found) which are of precious metals or consist of a hoard of coins. It allows the inclusion of archaeological finds that are associated with treasure (for example in a hoard of Bronze Age objects). It also allows for museums to have first refusal on the purchase of treasure objects, although they may not wish to do so, in which case the objects are then returned to the finder to sell (usually in agreement with the landowner).

Tree rings:

layers of new wood formed annually around the circumference of tree trunks; their variations in thickness are useful for studying environmental conditions as well as for tree-ring dating (dendrochronology).

Typology:

method of arranging classes of artefacts into sequences, normally according to improvements in design and efficiency (in the case of functional items such as axes) or alternatively according to changes in form or decoration (pottery, jewellery). The type-series produced in this way must first be dated independently if it is to be used for dating purposes.

V

Back to the top

Valletta Convention:

a document, containing general statements about the protection of the archaeological heritage, that came into force in 2001 and that has been accepted by most countries in the European Union. It contains a number of concepts supported by national bodies such as English Heritage, including a legal framework for archaeology within the planning process, and the principle that archaeology should be preserved ‘in situ’ rather than being excavated.

Varves:

annual deposits of silt on the beds of rivers or lakes that can be used (like tree rings) for absolute dating if related to a dated reference point.