**Selected Abbreviations and Symbols Used in This Report**

AMO Anaerobic methane oxidation

AMS Accelerator mass spectrometry

AOM Anaerobic oxidation of methane

ASTM American Society for Testing and Materials

BGHSZ Base of the gas hydrate stability zone

BP Before present

BSR Bottom simulating reflection

^13^C carbon-13

C Cell constant for ER measurements

C~1~ methane

C~2~ ethane

C~3~ propane

iC~4~ isobutane

nC~4~ normal butane

neoC~5~ neopentane

iC~5~ isopentane

nC~5~ normal pentane

2,2MC~4~ dimethylbutane

2MC~5~ 2methylpentane

3MC~5~ 3methylpentane

nC~6~ normal hexane

nC~7~ normal heptane

McC~6~ methylcyclohexane

C^2^ or C2 Calypso squared box core

ca. about

Calypso core Giant piston core

Carotte Core (in French)

CEREGE Centre Européen de Recherche et d\'Enseignement des Géosciences
de l\'Environnement

CF-IRMS Continuous flow-isotope ratio mass spectrometer

CHN Carbon, hydrogen, nitrogen

CuO/Pt Cupric oxide/platinum

DIC Dissolved inorganic carbon

DOE Department of Energy

e Void ratio

EDS Energy-dispersive spectroscopy

EDX Energy dispersive X-ray

ER Electrical resistivity

FF Formation factor

FID Flame-ionization detector

FISH-SIMS Fluorescent in situ hybridization and isotopic analysis

g Constant of acceleration due to gravity

GC Gas chromatography

GH Gas hydrate

GHF Gravity heat-flow corer, gravity corer with staggered welded
outriggers for holding temperature sensors and recorders, used to
acquire heat-flow measurements

GHSZ Gas hydrate stability zone

GOM Gulf of Mexico

Grav Gravity core

GSC Geological Survey of Canada

H~2~S Hydrogen sulfide

HRZ High reflectivity zone

HS¯ Hydrogen sulfide ion

I Current

IAPSO International Association for the Physical Sciences of the Oceans

IC Inorganic carbon

IFRAMER French Research Institute for Exploitation of the Sea

IMAGES International Marine Past Global Changes Study program

IODP Integrated Ocean Drilling Program

IPEV Institut Polaire Francais − Paul-Emile Victor

IR Infrared

κ Thermal conductivity

K Vane constant

K Temperature in degrees Kelvin

ka Kiloannum, time in thousands of years before present, used to express

age

k.y. Interval of time in thousands of years, used to express rate

LGM Last glacial maximum

LN~2~ Liquid nitrogen

LSCE Laboratoire des Sciences du Climat et de l\'Environment

MBARI Monterey Bay Aquarium Research Institute

mbsf Meters below sea floor

MC Mississippi Canyon

mfbc Meters from bottom of corer

Mfw Mass of fresh water in the sediment pore space

MIS Marine isotope stage

MMS Minerals Management Service

MOA Methane-oxidizing archael

Ms Mass of solid sediment grains without salt

Mss Mass of solid sediment grains, including salt

Msw Mass of sea water in the void space

Mt Mass of total specimen

MSCL Multi-sensor core logger

MST Multi-sensor track

N Nitrogen

n Porosity

NCSR National Council for Scientific Research

NGDC National Geophysical Data Center

OBS Ocean bottom seismometer

OC Organic carbon

OD Outside diameter

ODP Ocean drilling program

δ^18^O oxygen-18

PAGE Paleoceanography of the Atlantic and Geochemistry program

PC Calypso piston core

PCR Polymerase chain reaction

PDB Peedee Belemnite

ρd Dry bulk density

ρs Uncorrected grain density

ρsc Corrected grain density

ρw Wet bulk density

φ (phi) Measurement of grain size

π Pi, a constant equal to 3.14159...

POGO Multiple penetrations with heat-flow rigged gravity core

ppm Parts per million

ppt Parts per thousand

PVC Polyvinyl chloride

Q Total heat input per unit length of a thermal conductivity probe

R Electrical resistivity

Ro Sample resistivity

rRNA Ribosomal ribonucleic acid

RV Research vessel

Rw Resistivity from a known standard sea water

SD Subbottom depth (mbsf)

SEM Scanning electron microscopy

SEOS School of Earth and Ocean Sciences, University of Victoria, Canada

SMI Sulfate-methane interface

SMOW Standard mean ocean water

Spp Shear strength measured with a pocket penetrometer

SSU Small subunit

STP Standard temperature and pressure

Stv Shear strength measured with a Torvane device

Svs Shear strength measured with a laboratory vane shear machine

θ (theta) Angle of incidence

τ Spring constant used for Svs determination

t Time since the start of a heat pulse during a thermal conductivity
test

T Temperature

T Temperature change during a thermal conductivity test in degrees K

TC Total carbon

TC Thermal conductivity

UCS Unconfined compressive strength

UHP Ultra high purity

USGS U.S. Geological Survey

V Voltage

V Volume of sample

Vs Shear wave velocity

VS Vane shear

Vs Volume of sediment grains without salt, measured with a gas
pycnometer

Vss Volume of sediment grains and salt, measured with a gas pycnometer

Vsw Volume of sea water

Vt Calculated total specimen volume

Vv Volume of voids

WCs Uncorrected water content based on the solid grain mass

WCsc Corrected water content based on the solid grain mass

WCt Uncorrected water content based on the total specimen mass

WCtc Corrected water content based on the total specimen mass

XRD X-ray diffraction

γ Spring rotation to failure during vane shear test

γd Dry unit weight

γsub Submerged unit weight

γsw Unit weight of sea water

γw Wet unit weight