Cruise inventory

RRS John Murray JM4/68

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS John Murray (74MJ)
Cruise identifierJM4/68
Cruise period1968-03-12 — 1968-04-04
Port of departurePlymouth, United Kingdom
Port of returnPlymouth, United Kingdom
ObjectivesAims to:

1. Examine solid geology
2. Examine sediments, benthic macro and micro fauna
3. Gravity coring in St. George's Channel
4. Examine Mochras Horehole solid geology
5. Faunal variations
6. Nynydd Rhiw local magnetic anomalies
7. Coring in Cardigan bay to Pleistocene deposits
8. Geophysical traverses between Arklow and Dublin
9. Water samples taken at selected stations to gather data about phytoplankton populations
10. Drifter project
Chief scientistMaxwell R Dobson (University of Wales Aberystwyth Department of Geology)
Cruise reportRRS John Murray JM4/68 cruise report john_murray4_68.pdf — access key 'C' (0.58 MB) 
Ocean/sea areas 
GeneralIrish Sea and St. George's Channel
Celtic Sea
SpecificWelsh and Irish coast
Physical oceanography 
Surface measurements underway (T,S)Description: water samples
Subsurface temperature and salinity measurementsDescription: water samples
Surface drifters/drifting buoysQuantity: number of deployments = 300
Description: surface and bottom drifters
Chemical oceanography 
OxygenDescription: water samples
NitrateDescription: water samples
SilicateDescription: water samples
Biology and fisheries 
Phytoplankton pigs (eg chlorophyll, fluorescence)Description: chlorophyll a
PhytoplanktonDescription: water samples
ZoobenthosDescription: faunal variations seen in cores
Geology and geophysics 
DredgeDescription: sediments, benthic macro- and microfauna
GrabDescription: reference samples every 15 miles
GrabDescription: sediments, benthic macro- and microfauna
Core - rockDescription: gravity coring
Core - soft bottomDescription: long piston and short gravity cores, faunal variations
Core - soft bottomDescription: sediments, benthic macro- and microfauna
Bottom photographyDescription: sediments, benthic macro- and microfauna
Single channel seismic reflectionDescription: continuous reflection profiling
Magnetic measurementsDescription: magnetometer, local magnetic anomaly investigation