P

Pacific coast

pack ice

packstone (not packestone)

paleo Words with the prefix paleo (not palae) are rarely followed by a hyphen: paleoatmosphere, paleoceanography (not paleo-oceanography), paleoclimate, paleoenvironment, paleontology, paleovalley, Paleoarchean, Paleoproterozoic, Paleozoic, and Paleocene (Note lower Paleozoic, but Lower Paleocene).

paleontological (not paleontologic)

palimpsest

palsa (pl. palsen)

Pangaea (not Pangea)

parabituminous

paraffin

paragneiss, but para-andesite

parallel, paralleled

parallel lamination

parallel structures, parallel constructions Parallel structures commonly yield economy of words, clearer meaning, and pleasing effects. See 'Parallel structures' in 'Grammar'.

paralyze

parenthesis (pl. parentheses)

partially, partly Partially is commonly misused for partly, as in the sentences: 'The area is partially drift covered'; 'The orebin is partially filled'; or, 'The granodiorite is partially altered'. Partially implies 'partiality', and should never be used without first considering the claims of partly. Partially can mean 'incompletely', but for in part, always use partly.

participles The two participles of the verb in English are the present participle (which always ends in -ing; e.g. standing) and the past participle (ending in -d, -ed, -n, -en, and -t; e.g. shattered). See also DANGLING PARTICIPLE.

particular Do not misuse this strong adjective. Use it for emphasis. The noun to which it is attached should be one that you need to single out and emphasize.

passive voice See 'Active and passive voice' in 'Grammar'.

past, passed The word past can be used as a noun: Fossils are relics of the past, as an adjective: Fossils are used to interpret past events, or as a preposition: The avalanche roared past my tent in a matter of seconds.

Passed is the verb form: I passed the hammer to my assistant.

patch reef

pay zone

peatlands, peat moss

pebble conglomerate, but chert-pebble conglomerate

pelite

pellet

penecontemporaneous The prefix pene means 'almost, nearly', or 'all but'.

peneplain (n.), peneplaned (vb.)

peneplanation

Pennsylvanian

per This is a Latin preposition and should be confined to its own language (e.g. per cent). Say eight cents a mile (not eight cents per mile). Some expressions do, however, demand per, such as miles per gallon and kilometres per hour.

perbituminous

per cent (from per centum) (not percent) The per cent sign (%) can be used in the text where numbers are common, but otherwise use the term per cent. There is no space between the numeral and the per cent sign: 10% plagioclase, but there is a space between a word or abbreviation and the sign: weight %; wt %.

percentage Instead of 'a large percentage of', use many; instead of 'a small percentage of', use few.

perceptible

Permo-Carboniferous (when both periods are considered as a unit).

persistent

person In grammar, pronouns belong to three persons and occur in the singular and plural. First person: I (singular), we (plural). Second person: you (singular and plural). Third person: he, she, it (singular), they (plural).

In modern writing, scientists are encouraged to use the first person I and we. When there are two or more authors, use We found instead of 'It was found' (passive voice) or 'The authors found' (active voice, but verbose). Use I for a singular author, not the 'editorial' we. Be consistent in your use of person.

See also 'Active and passive voice' in 'Grammar'.

personal, personnel Personal means 'individual, private', personnel means 'staff'.

persuasive, pervasive Persuasive means 'able to persuade'. Pervasive means 'spreading through, saturating'.

Petro-Canada

petrographic (not petrographical)

petrological (not petrologic

PGE See PLATINUM GROUP

phase A phase means 'a stage of transition or development' (not an aspect). A mineral is a phase, so that 'mineral phase' is redundant. An exception applies for broad discussions or comparisons, as in mineral, melt, and gas phases.

At one time phase was widely used in petrology in reference to the compositional units, variants, or facies of igneous intrusions, presumably with the implication that these units represent different stages of differentiation. Nowadays, though, the word is deeply entrenched in the sense of phase equilibria, where a phase is a solid, liquid, or gas. It seems advisable, therefore, to avoid the older usage.

phenoclast, phenocryst

phenomenon (pl. phenomena)

phosphorus (n.), phosphorous (adj.)

photomicrograph (not microphotograph)

phylum (pl. phyla)

-phyric As a suffix -phyric is usually preceded by a hyphen: feldspar-phyric, hornblende- feldspar-phyric, olivine-phyric, plagioclase-phyric, pyroxene-phyric, quartz-phyric.

pico The prefix pico (symbol p) indicates the multiple 10^-12.

pilotaxitic

pinch-out (n. and adj.), pinch out (vb.)

pipeline

planar crossbedding

planetable

plate Refers to full page groups of photographs or photomicrographs in paleontological reports only. Subordinate or individual illustrations within a plate are called 'figures':

All other illustrations of paleontological (less than page size) or other material are called 'Figures' with a captial 'F' to distinguish them from the 'figures' with a lower case 'f' in the plates.

See also FIGURE.

plateau (pl. plateaus)

platy (not platey)

platinum group, but platinum-group element (PGE), platinum-group elements (PGEs)

pleochroic

Pliensbachian A stage of the Global Stratigraphic Chart.

plus, plus/minus (±) In mineral assemblages and metal-deposit descriptions, there are no spaces on either side of the + or ±.

In stating error ranges in age determinations, a space is used on either side of the ±.

plutonics Do not use plutonics when 'plutonic rocks' is meant. See also CLASTICS; INTRUSIVES; VOLCANICS, METAMORPHICS, CLASTICS.

poikilitic

poikiloblast

point bar, but point-bar deposit

polarize

Pole, the Pole, North Pole

polychaete

porphyroblast

porphyry, porphyritic

portion Portionis commonly misused for part, as in, 'the northern portion of the area'. Portion refers to a share, as in, your portion of the profits.

post Most words with the prefix post, meaning 'after' or 'later', are not hyphenated: postdate, postdepositional, postglacial, postmagmatic, postorogenic, postoperative, but post-Mississippian, post-tectonic, post-Tertiary, and post-Paleozoic. See also PRE; SYN.

post office The Red Lake post office.

potassium feldspar (not potash feldspar). See also K-FELDSPAR.

pothole

pneumatolysis

pneumotectic

practicable, practical Practicable means 'that which can be done, feasible'. Practical means 'relating to or applicable in practice', the opposite of theoretical. Other opposites are impracticable and unpractical or impractical.

practically Do not use practically as a substitute for almost, nearly, or virtually. The section may be 'almost complete', but it is not 'practically complete'. It is incorrect to write that a geologist 'practically proved the hypothesis', when in fact most of the hypothesis' terms remained unexplained.

practice (n.), practise (vb.)

pre Most words with the prefix pre, meaning 'before' or 'previous in time', are not hyphenated: Precambrian, precede, predate, predetermined, preglacial, premetamorphic, but pre-Devonian brachiopods, pre-empt, pre-existing, pre-Fraser Valley Glaciation, pre-Jurassic, and pre- Wisconsinan. See also POST; SYN.

precede (not preceed)

precision See ACCURACY.

prediction See FORECAST.

prefer, preference

preferable Preferable should not be used with a comparative ('more preferable' is incorrect).

preoccupy

prerequisite

presently Presently once meant 'immediately'. It currently has two meanings: 'after a short time, in a little while, before long, shortly, soon', and 'now, at present, currently'. Writers should therefore ensure that when they use presently, their meaning is not ambiguous.

presume See ASSUME.

preventive (not preventative)

principal, principle Principal, as a noun or as an adjective, always means 'chief'. Principle is used only as a noun and means 'a rule, law, or moral value'.

prior to (prep.) Before is preferred. Prior as an adjective is correct.

proceed

prodelta, proglacial, prograde

program (not programme), programmer, programming Program, the preferred spelling, was the common form, even in Britain, until the nineteenth century.

prohibit from doing, but forbid to do.

proportion Use this word only to refer to statistics. Instead of 'a proportion of', use some; instead of 'a large proportion of', use many.

proposition Proposition means 'something put forward for discussion, or as the basis of argument'; it should not be used as a synonym for plan or project.

proto-Atlantic Ocean

proven Accepted usage is only in the legal sense. As the participle of prove, the form proved should be employed. Proven may be correctly used as an adjective.

provenance

provided that Introduces a stipulation (on the condition that) and is preferable to 'providing'.

province Capitalized as in Province of Quebec, Churchill Province.

psammite

pseudo As a prefix pseudo is rarely followed by a hyphen: pseudobreccia, pseudotachylyte.

pseudomorph Pseudomorphs of cassiterite after orthoclase. Avoid using pseudomorph as a verb.

P-wave

pyroclastics See INTRUSIVES.