Suggestions for translators and other dictionary users

In the same way as there is no royal road to geometry, translators soon learn there is no such thing as a one-stop dictionary. The authors of this fourth edition are well aware of the difficulties faced by seekers after reliable information, who undertake a process that may be compared with trawling for clues in an ocean of words. Hence, we offer the following points of guidance in the hope that readers will excuse any shortcomings they encounter while attempting to use the present dictionary.

When in doubt about the best choice for translation, the puzzled reader would be well advised to consult other sources and compare definitions between the two languages. Indeed, this approach is the core of our dictionary-making philosophy, and we have not hesitated to check our facts against monolingual dictionaries and textbooks (in particular, two excellent dictionaries of geology: Allaby and Allaby, 1999; Foucault and Raoult, 2000). We trust that this has had a significant impact on the cogency and consistency of the terminology used in the present dictionary.

First of all, this dictionary was never intended to provide encyclopaedic information, and still less give a comprehensive coverage of all the earth sciences. Nevertheless, our combined experience of academic teaching and professional translation has enabled us to judge the quality of numerous disparate sources. Whenever we consider some proposed translation is inappropriate, misconstrued or simply wrong, we have noted the anomaly and taken corrective measures.

In the system adopted here, some main entry terms are classified as “unusual”, “obsolete” or “rare”, while preferred terms are indicated as “better:” Any other information in bold type presented in brackets after the main entry term should be taken as a context. Otherwise, close equivalents are separated by commas with no particular order of preference and synonyms are indicated as “syn:”

Subject label codes (see list below) are given in italics after the relevant translation equivalent in the English-French section, while they are generally given after the main entry term in the French-English section (except in the case of complex sub-entries).

Where appropriate, the semi-colon is used to separate different shades of meaning in the translations of a given term. To resolve certain complex cases, we number the different equivalents according to their subject areas. The short explanatory notes found in brackets after certain terms are not to be taken as definitions; they merely help in avoiding possible ambiguities and pitfalls.

A number of abbreviations and acronyms are given in brackets after the term, but the reader should consult the list included at the end of the dictionary for a more comprehensive compilation.

To distinguish spelling variants, we provide some indication of the differences between American and British English by placing labels after the terms in question, for example: modelling (GB) and modeling (US).

Other types of variant are not geographical, for instance, feldspar, feldspathic and feldspathoid are now the most commonly used forms in British and American English, but felspar, felspathic and felspathoid are still encountered in some publications. Such variants are listed in bold after the term entry, separated by commas.

Decimals, Commas and DatesScientific Units and Symbol

Scientific Units and Symbols

Geographic Names and Locality

Stratigraphic and Tectonic Names


Common Errors

Use of Tenses and Describing Past Events

Avoid the impersonal and do not be too passive

Link words at the beginning of a sentence

Expressing possession

Abstract vs. concrete

False friends


Other sources consulted

Decimals, Commas and Dates

Watch out for the different conventions in French for quoting decimals and separating the thousands (0,25 for one quarter, and 25.000 for twenty-five thousand). These rules are the opposite of those used in English-speaking countries (0.25 and 25,000). To make the numbers easier to read, they may be divided into groups of three by a space (i.e. 25 000). To add to the confusion, calendar dates in American usage are generally given in a different order compared with British English (for example, 9th November 2003 may also be written as November 9th 2003, and is abbreviated as 09.11.03 in the United Kingdom and 11.09.03 in the United States).

Scientific Units and Symbols

The symbols and prefixes used in the International System of Units are codified by the Bureau International des Poids et Mesures; the official Système International web site in France is:

For conversion tables, with symbols and abbreviations, see “A Dictionary of Units” by Frank Tapson (Exeter University, UK), which is available on line:

A summary table of the most frequently used conversion factors is given as an annex to this present edition of our dictionary.

A common error in English is "many kms” (plusieurs km), which should be written "many km" to avoid a conflict with kms = km per second. You should also be very careful not to mix up the symbols for second and volt with siemens (electric conductance: S) and sievert (dose equivalent: Sv).

Geographic Names and Locality

In French, l'océan Atlantique; in English: Atlantic Ocean (both adjectival name and category noun get a capital letter).
Likewise: le bassin de Paris = the Paris Basin, NOT the Paris basin.

Translators sometimes need to consult a map to discover their bearings. For example, is “au nord du bassin de Paris” within or just outside the area defined by this sedimentary basin? This problem can be circumvented by using “the northern part of” or “farther north than”, as the case may be.
Although the left bank of the Seine is familiar to tourists, English-speaking people find it more pragmatic to use compass directions (for example, the South Bank of the Thames).

Stratigraphic and Tectonic Names

In French, Tertiaire inférieur = Lower Tertiary (both name and adjective get a capital letter): vieux grès rouge = Old Red Sandstone; Cretaceous System (and Period); Holocene Epoch. The rules of nomenclature in English are standardized by the I.U.G.S. (see the International Stratigraphic Chart, which can be downloaded from:

Remember that intervals of geological time are subdivided into early, middle and late, whereas the corresponding rock formations are referred to as lower, middle and upper.

The names of orogenies are not formalized in the same way as stratigraphic units, and the modern trend is to speak in terms of the objects (Variscan belt and Variscides) rather than the episode (Variscan orogeny).


Hyphens are used in English to link together adjectives qualifying a noun, for example: a grey-green sandstone. However, an adjectival modifier will eliminate the need for a hyphen, e.g. a greyish green sandstone. When hyphenated compounds are used very frequently (e.g. beach-ridge, ground-water, land-mark), there is a natural tendency to combine them as single words. In this way, we obtain beachridge, groundwater and landmark, which are used both as adjectives and as nouns. Despite this, some familiar combinations have remained separate, e.g. sea level and water table. In such cases, a hyphenated adjective is used to qualify the type of phenomenon or object involved (i.e. sea-level rise or water-table level).

Common Errors

Accident and accidenté (Fr.) refer to uneven relief or features generally caused by faulting. Nevertheless, certain types of concretion are known as “accidents” in French, while a terrain can be described as “accidenté” even when no faulting is involved. To avoid any misunderstanding, the noun should NEVER be translated as "accident” in the sense of a chance occurrence.

Actuellement (Fr.) signifies "at the present" or "now". "Presently" is ambiguous in American English, meaning 'at the present moment", while in British English, it has the connotation of "soon" or "maybe next week”. For clarity, use "currently" or “now". The adjective actuel in French should be translated into English as “current” or “present-day”.

Actual is used in English as an adjective to mean "real" or "true", whereas the adverb actually is equivalent to “really" or ”in actual fact”.
Actualism in English and actualisme in French mean the same thing, i.e. the philosophy of using the present as the key for interpreting the past, but in geology is better to use the classic term “uniformitarianism”.

Altitude (Fr.) means height, elevation or altitude. Altitude (Eng.) usually refers to atmospheric heights, not land features ("elevation"); e.g. a jet aircraft flies at 9 000 m altitude, over Mt Everest, which has an elevation of 8 000 m.

Arctic and Antarctic (Eng.) are commonly misspelt in the US as "Artic" and "Antartic" (where the middle "c" s not pronounced).

Datation (Fr.) should be translated as "dating" in English. In fact, "datation" is an example of an incorrect loan translation. Other words falling into this category are “alimentation” and “basculating”, which are erroneously used in geology instead of “supply” and “tilting”.

Disposer de in French means “to have” or “to keep”, and NOT “to dispose of”.

Défendre must not be taken to mean “defend” when it really means “forbid”.

Estimer is often mistranslated as “to estimate”, but it also means “to consider”.

Eustatisme (Fr.), Eustasy (Eng.): although the suffix -ism often occurs in philosophical and political terms (e.g. Marxism, Existentialism and conservatism), it is more rarely used in geology (e.g. Neptunism, Plutonism, uniformitarianism and metamorphism). Eustasy is based on the Greek word "stasis" (as in isostasy, which gives the adjective isostatic), so words with this suffix should NEVER be spelt with a "c", there being no such letter in the Greek alphabet. Also for reasons of etymology, the noun “analysis” gives rise to the verb “analyse”, but many authors (and automatic spell checkers) persist in using “analyze”.

Evidence, évident and évidemment (Fr.) are tricky to handle, since they imply the existence of an obvious fact. However, English is more prudent, simply requiring some evidence (often translated as “preuves” in French) before coming to a conclusion. Bear in mind that nothing is ever obvious in science, so the reader will prefer to see a statement with “evidently or clearly” rather than “of course”.

Extension (Fr) in tectonics refers to the distension or stretching suffered by rocks in a tensional regime. In geography, however, the correct translation into English is “extent”.

When employed in a geological context, important (Fr.) means "thick", "considerable". "voluminous " or "major" (practically NEVER “important" in the English sense).

Intérêt (Fr) should only be translated as “interest” when dealing with financial matters. In other contexts, it can be taken as meaning “advantage” or “importance”. For example, a method can be described as “of interest” if it offers certain advantages. Be careful to translate the antonym “inconvénient” as “disadvantage” and not “inconvenience”.

Permettre (Fr.) can be translated in many different ways according to context, but most commonly can be taken in English as “to make possible" or simply “to lead to": note that “to enable", "to allow" and “to permit” are more difficult to master, so be prudent.

Présenter (Fr.) may be used in the sense of “to exhibit” a characteristic, while “to present” a symptom is only used in medicine.

Pétrole (Fr.) is normally the equivalent of petroleum, but can also be used to designate the refined hydrocarbon fraction known as paraffin in British English and kerosene in American English. To make matters worse, petrol in British English is called “gas” in American English.

Precise is not a verb in English: préciser (Fr.) should be translated as "to specify", “to detail", “to stipulate", or even “to determine”, according to the context.

Prétendre (Fr.) is a classic false friend, and can NEVER be translated as “to pretend”. In fact, it means “to claim” or “to maintain”. The correct translation of “pretend” in French is “faire semblant”.

Réaliser (Fr.) normally means “to carry out,” while “to realize” refers to the state of becoming aware of something.

Vaste (Fr.) in geology means "broad", "wide", "widespread" or “extensive” (hardly ever “vast", which is only appropriate for astronomic distances, or a voluminous amount of material).

Use of Tenses and Describing Past Events

Although the present tense can make history come alive, it is usually clearer to use the simple past when describing a sequence of events. For example: “the sediments were laid down during the Cretaceous, when dinosaurs roamed the Earth”.

The translation of “depuis” poses a considerable problem, because it can be rendered as “since”, “from” or “for” according to how the event is defined (from a specific point in time, or over a given duration). Thus, we should say: “No dinosaurs could be found because they had been extinct since the end of the Cretaceous”. When the event takes place intermittently or over some interval of time, it is more logical to use “during” (“pendant” or “au cours de” in French) as in the example: “Dinosaurs roamed the Earth during the Cretaceous”. However, “dinosaurs began to roam the Earth from Jurassic times onwards” is translated as “les dinosaurs ont commencé à errer sur la Terre à partir du Jurassique”.

Avoid the impersonal and do not be too passive

The author(s) of a scientific article in English accept responsibility by using the first person, and should not hide behind the passive voice. Use the passive voice when the agent is unknown, or if you prefer to remain vague about the responsibility.

Link words at the beginning of a sentence

It is good style to place link words at the beginning of a sentence - followed by a comma - when there is a clear relation with the preceding sentence or a following clause (for example: However, … Moreover, … Finally, … Thus, …). In English, “since” can express a logical or a time relationship, which explains why some editors insist on replacing it with “as” to avoid the perceived ambiguity. However, the context should indicate which sense is intended, so it is better to choose “since” or “because” rather than risk confusion with constructions using “as”.

Expressing possession

Genitives with apostrophes and idiomatic contractions should be avoided in scientific discourse (except in technical terms such as Pelee's hair, Stokes' law, etc.). So be careful to avoid the famous “electrocution’s danger”, and remember that inanimate objects and abstract concepts prefer the construction with “of”.

Abstract vs. concrete

A number of concepts in French are translated as objects in English (e.g. "volcanisme" in French is often the equivalent of "volcanic rocks" in English, but can be taken as meaning “volcanic activity” or even “volcanicity”). This can lead to confusion between object and process, for example “magmatisme” could be either a plutonic igneous suite or an episode of igneous activity.

An orogeny corresponds to a mountain-building episode that occurs in some part of the Earth’s crust (such as the Variscan orogeny). In French, this concept is translated by “orogenèse”, which covers not only the general process itself but also the formation of specific mountain belts. Strictly speaking, the process of mountain building should be called orogenesis (or diastrophism), whereas the result is an orogenic belt or an orogen. The outdated concept of the “orogenic cycle” is based on the theory of geosynclines, and should now be avoided in translation. It is better to use terms such as “deformational phase”, “tectonometamorphic event” or “tectonic activity”.

False friends

Beware of the difficulties caused by "false friends" in both languages. For example, "schist" (Eng.) is equivalent to "schiste cristallin" (Fr.), while "schiste" or “schiste argileux” in French should be translated as "shale" in English. It is usually possible to avoid such pitfalls by referring to the definitions of terms. In this dictionary, we give explanatory notes to take account of this type of problem. From careful comparison of entries in the English-French and French-English sections, it can be seen that "shaly" does not have the same sense as "schisteux", and should be rendered as ''argileux". An example of a double-crossing false friend is the term “phyllite” in English, which designates a rock type corresponding to “phyllade” in French, whereas “phyllite” in French denotes a mineral belonging to the sheet silicates.

Even within a particular subject area, the reader will find that some words have several meanings in one language, but only one in the other. For example, outside the domain of taxation, “abatement” in English refers to methods for controlling or lowering some quantity. In French, on the other hand, “abattement” can be the method for achieving this reduction as well as the amount involved. Thus, we talk about noise abatement, but measure the flux depletion (of nitrates, for example) due to pollution control.


During the different phases of revision of this dictionay, numerous terms were checked against records in a database (GEOBASE) developed by Dr M.S.N. CARPENTER. This database is available from "European Language Resource Association -Distribution Agency", 87, avenue d'Italie, 75013 PARIS

Main sources used for the compilation of terminological records:

CILF, Banque des Mots 8 et 25 (Géotechnique; Glissements de terrains) CILF, Banque des Mots 30 (Vocabulaire de la sismologie) CILF, Banque des Mots 37 (Erosion - Transport - Sédimentation : RAMPON) CILF, Banque des Mots 39 (Nodules polymétalliques : JÄGER) CILF, Banque des Mots 44 (Vocabulaire de la sismologie) CILF, Banque des Mots 44 (Vocabulaire de la tectonique: NICOLAS) CILF, Vocabulaire de l'Hydrologie et de la Météorologie, 1978 CILF, Vocabulaire de la Géomorphologie, 1979 CILF, Dictionnaire de l'Environnement, 1992 MERLE, 1994 - "Nappes et chevauchements..." Editions Masson ROUTLEDGE, 1994 - French Technical Dictionary, vol 1 French-English

Other sources consulted:

ALLABY & ALLABY, 1990 - Concise Oxford Dictionary of Earth Sciences - Oxford University Press CARA, 1989 - "Géophysique", Editions Dunod FOUCAULT & RAOULT, 1995 - Dictionnaire de Géologie, Editions Masson GILLULY et al., 1968 - "Principles of Geology", Freeman GRAU, 1994 - Glossaire des principaux termes techniques de la prospection sismique, Éditions Technip HARRAP'S Science Dictionary, 1985 HILLS, 1963 - "Elements of Structural Geology", Methuen HOLMES, 1965 - "Principles of Physical Geology", Nelson LE PETIT ROBERT, 1972 - Société du Nouveau Littré LONGMAN Dictionary of the English Language, 1993 MOUREAU & BRACE, 1993 - Dictionnaire des sciences et techniques du pétrole, Éditions Technip MICHEL & FAIRBRIDGE, 1992 - Dictionnaire des Sciences de la Terre