RRS John Murray JM4/68
Cruise summary report
| Cruise Info. | |
| Ship name (ship code) | RRS John Murray (74MJ) |
| Cruise identifier | JM4/68 |
| Cruise period | 1968-03-12 — 1968-04-04 |
| Status | Completed |
| Port of departure | Plymouth, United Kingdom |
| Port of return | Plymouth, United Kingdom |
| Purpose | Research |
| Objectives | Aims 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 scientist | Maxwell R Dobson (University of Wales Aberystwyth Department of Geology) |
| Cruise report |  (0.58 MB) |
| Ocean/sea areas | |
| General | Irish Sea and St. George's Channel Celtic Sea |
| Specific | Welsh and Irish coast |
| Measurements | |
| Physical oceanography | |
| Surface measurements underway (T,S) | Description: water samples |
| Subsurface temperature and salinity measurements | Description: water samples |
| Surface drifters/drifting buoys | Quantity: number of deployments = 300 Description: surface and bottom drifters |
| Chemical oceanography | |
| Oxygen | Description: water samples |
| Nitrate | Description: water samples |
| Silicate | Description: water samples |
| Biology and fisheries | |
| Phytoplankton pigs (eg chlorophyll, fluorescence) | Description: chlorophyll a |
| Phytoplankton | Description: water samples |
| Zoobenthos | Description: faunal variations seen in cores |
| Geology and geophysics | |
| Dredge | Description: sediments, benthic macro- and microfauna |
| Grab | Description: sediments, benthic macro- and microfauna |
| Grab | Description: reference samples every 15 miles |
| Core - rock | Description: gravity coring |
| Core - soft bottom | Description: sediments, benthic macro- and microfauna |
| Core - soft bottom | Description: long piston and short gravity cores, faunal variations |
| Bottom photography | Description: sediments, benthic macro- and microfauna |
| Single channel seismic reflection | Description: continuous reflection profiling |
| Magnetic measurements | Description: magnetometer, local magnetic anomaly investigation |
