DCO Writing Style Guide

These guidelines are intended to help you prepare DCO-related documents, including proposals, project updates, and web features. In general, please refer to the Chicago Manual of Style, 16th ed., 2010 (generally available through your institution library or by personal subscription here). Specific examples and exceptions are listed below.

Abbreviations and Acronyms

In general, avoid using abbreviations, especially if they would occur only rarely in the text. Introduce abbreviations or acronyms in parentheses after spelling out the first occurrence, for example, European Geosciences Union (EGU), International Ocean Discovery Program (IODP), or rare earth element (REE).

Always spell out the word “and”, except in cases where “&” is an official part of a proper name.

Deep Carbon Observatory
Spell out first reference then use “DCO”. For internal use, including on the public pages of the DCO web portal, there is no need to include the parenthetical (DCO) with the first reference.

Specific examples when talking about DCO:

Upon completion of this initiative, DCO will yield...
Advanced techniques, instruments, and technologies developed under the auspices of DCO...
The Engagement Team will provide the DCO community with...
Working with DCO leadership, the DCO Secretariat will...
The success of DCO’s workshop on industry partnerships...
Distribution of the DCO newsletter...
DCO’s Deep Life Community is led by...

Deep Carbon Observatory's Guiding Questions
When referring to DCO’s guiding questions, place the words in this order:
quantities, movements, forms, and origins.

How much carbon does Earth contain, and where is it?
What is the nature of Earth’s deep carbon cycle?
What forms of carbon exist within Earth?
What can deep carbon tell us about origins?

Deep Carbon Observatory-Specific Acronyms
These are examples of acronyms for use in documents for the DCO website or other informal DCO purposes.

DCO Communities
When referring to specific DCO Communities, “Community/Communities” should be capitalized. When referring to the entire community of DCO scientists, or DCO community, “community/communities” should not be capitalized.

Extreme Physics and Chemistry (EPC) (use “and” rather than “&”)
Reservoirs and Fluxes (RF) (use “and” rather than “&”)
Deep Energy (DE)
Deep Life (DL)

Other DCO entities

Engagement Team
Data Science Team
DCO Science Network
Executive Committee (EC)
Scientific Steering Committee (SSC)
DCO leadership (EC + SSCs)

Alfred P. Sloan Foundation (Sloan Foundation)


Use a comma before “and” in a series of three or more items (the Oxford comma). Use commas, not dashes, to set off clauses.

Compound words

Consult Merriam-Webster's Collegiate Dictionary (Webster) for accepted spelling of compound words. Acceptance is determined by convention and sometimes appears idiosyncratic. Rely on Webster’s for spelling of permanent compounds, such as seafloor (noun) and saltwater (adjective), and for hyphenated compounds, such as life-form and mid-ocean. If a compound noun does not appear in the dictionary, it is generally best to spell it as two words.

Chemical Names and Formulae

In documents prepared by DCO for a public audience, we will ensure that all chemicals are named in full (e.g. carbon dioxide not CO2). For DCO web portal content, using conventional chemical symbols and formulae is perfectly acceptable.

Dates and Times

Dates should be written Day Month Year, without commas separating each unit, for example, 27 March 2013. When it is necessary to include the day of the week, such as in an agenda, use this format: Monday, 2 March 2014.

Plurals of years require no apostrophe; for example, 1970s and 1980s.
Use B.C. and A.D. (with periods) rather than B.C.E. or B.P. and C.E.
Please use the following format for times: 10:30 a.m. / 9:15 p.m.

Hyphenation and Prefixes

Use hyphens to join two or more consecutive words that make up a single modifier of a word that follows. In general, a hyphen is not used when these consecutive words appear after the word they modify. Do not hyphenate compounds with adverbs ending in ly. Section 7.90 in The Chicago Manual of Style (7.87 in online version) is an excellent guide to hyphenation for compounds and prefixes.

tube-building worms worms engaged in tube building
well-known effect the effect is well known
deep-dwelling species species that dwell in the deep ocean
10,000-square-kilometer tract an area of 10,000 square kilometers
commercially-drilled areas the area is commercially drilled
sediment-filled something is filled with sediment
iron-magnesium an alloy of iron and magnesium
high-pressure experiment the experiment required high pressure

In general, do not use a hyphen with simple prefixes. See extensive but nonexclusive lists of preferred spellings in Webster’s.

multicellular, multiyear
noncommercial, nonmigratory
recolonization, reexploration
uniaxial, unicellular, but single-celled and one-celled
subaqueous, subsurface
hydrothermal, hydrocarbons
epifluorescence, epistatic


Use italics for names of ships and submersibles (but not abbreviations designating type of vessel such as DV, RV, or EV), titles of books and journals, and genus, species, and subspecies names (but not designations following such names). Also use italics for et al., and in situ, in silica, in vivo etc. Use roman type (not italics) for names of research programs, titles of chapters and journal articles, and taxonomic divisions higher than genus.

DV Chikyu, RV JOIDES Resolution, USCGC Healy
Deep Carbon Observatory (DCO)
Hyperoodon sp.
seed shrimps (class Ostracoda)
Carbon in Earth
American Mineralogist
Hazen et al.
We analyzed the samples in situ

Numbers and Units

Spell out fractions and numbers one through nine, then use numerals. In a sentence containing numbers both larger and smaller than 10, use numerals for all things of one kind. Use commas in numbers of four or more digits (except addresses, dates, and page numbers). Spell out million and billion. Use numerals with percent and units of measure. Treat days, weeks, months, and years as parts of a calendar rather than units of time.

two diamonds and nine garnets
2 diamonds, 9 garnets, and 21 other minerals
We found 2 diamonds, 9 garnets, and 21 other minerals in four meteorite fragments.
5,000 tons, 51,000 tons
four-week cruise, one month, 30 days
two-thirds full
1 million
4 liters (about 1 gallon)
When providing a range of numbers, use the word “to” instead of a dash: 25 to 30, not 25-30.
2 percent (always spell out the word “percent” except in tables or column headings)

Use the currency sign with numerals; for example, $3,500 and $5 million (dollars), €10 (euros), £10 million and £250,000 (pounds).

Use the International System of Units (SI) generally, followed, if necessary, by equivalents in parentheses. For example:

2 to 3 centimeters (about 1 inch)
1,500 meters (about 5,000 feet)
ppm/ppb (parts per million/parts per billion)
MPa, GPa (tons per square inch)
Gy (billions of years)
Mb (megabase/millions of base pairs)

Spelling and Capitalization

the Deep Carbon Observatory, DCO, the DCO program, DCO Communities, DCO project
Figure 2, Table 5 (or use guidelines provided by the outlet for your publication)
Earth – not the Earth or the earth (compare: Jupiter vs. the Jupiter)
hot spots – not hotspots
sulfide – not sulphide
under way (adv.) (work is under way)
volcanoes, not volcanos
daylong/weeklong – not day long, day-long, week long or week-long (per Merriam-Webster)

American vs. British spelling

harbor – not harbour*
color – not colour*

*Depending on the outlet for your publication, there are times when the British rather than American English spellings of certain words are more appropriate, so please follow your publication’s guidelines when deciding on whether to use British or American spelling for words such as harbor and color.

Wired words

the Internet
website, webpage, web-based, DCO web portal, the Web (we have made a choice to use the lower case option for “web” except when used as a proper name (“the Web”).

Word processing

Insert page numbers.
If paragraphs are indented, use a tab.
Use indents and tabs, not the space bar, to align text, especially in tables.
Do not insert extra returns between paragraphs.
Do not use automatic hyphenation.
Do not insert more than one space after a period.
Active voice: According to Sloan Foundation preferences, please use an active rather than a passive voice in all DCO documents where possible. Examples of active vs. passive voice can be found on many websites including:


Preferred dictionary: Merriam-Webster's Collegiate Dictionary, 11th ed., 2003 (available through Amazon or most bookstores worldwide)
Online dictionary: Merriam-Webster Online Search www.merriam-webster.com free version with advertisements) or PC and MAC versions downloadable from the publisher ($19.99 US)
General style guide: The Chicago Manual of Style, 16th ed., 2010 (print edition available from the publisher and Amazon)
Online style guide: The Chicago Manual of Style (available by subscription from the publisher)
Online glossaries: Glossary of Geology, http://en.wikipedia.org/wiki/Glossary_of_geology; British Geological Survey Glossary, http://www.bgs.ac.uk/discoveringGeology/glossary.html; Geology and Earth Science Terms and Definitions, http://geology.com/geology-dictionary.shtml; USGS Geologic Glossary http://geomaps.wr.usgs.gov/parks/misc/glossarya.html
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