Cruise inventory

RRS John Murray JM3/70 Leg 2

Cruise summary report

Cruise Info. 
Ship name (ship code)RRS John Murray (74MJ)
Cruise identifierJM3/70 Leg 2
Cruise period1970-04-04 — 1970-04-13
StatusCompleted
Port of departureCork, Ireland
Port of returnBarry, United Kingdom
PurposeResearch
ObjectivesThe main purpose of the cruise was to survey by seismic, gravity and magnetic methods the ares to the south west of Ireland leading across the shelf to the Porcupine Seabight and the continental margin. Seismic refraction lines were required to provide information of the shallow layers.

Additional experiments were planned:
1. the evaluation of a vertical hydrophone array for use in water of oceanic depths
2. the evaluation of aquaflex as a seismic source for refraction measurements at sea using sono-buoys
3. geophysical traverses across the Nymphe Bank and Bristol Channel
4. a gravity traverse into Carmarthen Bay
5. evaluation of effect of ship's magnetic field on proton magnetometer towed at various lengths and headings
6. bottom sampling for foraminifera and ostracoda in the River Shannon estauary
Chief scientistDerek J Blundell (University of Birmingham Department of Geology with Geophysics)
Cruise reportRRS John Murray JM3/70 Leg 2 cruise report john_murray3_70.pdf — access key 'C' (0.41 MB) 
Ocean/sea areas 
GeneralCeltic Sea
SpecificCeltic Sea
Track chartsRRS John Murray JM3/70 Leg 2 cruise track — john_murray3_70trk.pdf (00 MB) 
Measurements 
Physical oceanography 
Other physical oceanographic measurementsQuantity: number of stations = 10
Description: seawater samples
Biology and fisheries 
PhytoplanktonQuantity: number of stations = 10
Description: plankton sampling
ZooplanktonQuantity: number of stations = 10
Description: plankton sampling
Geology and geophysics 
GrabQuantity: number of stations = 10
Description: shipek grab for sediment samples
Seismic refractionQuantity: number of surveys = 3
Description: sonobouy seismic refraction lines
Gravity measurementsQuantity: number of surveys = 8
Description: gravity/magnetic traverses
Magnetic measurementsQuantity: number of surveys = 8
Description: gravity/magnetic traverses
Other geological/geophysical measurementsQuantity: number of surveys = 2
Description: sparker used on traverses 70/14 and 70/16
Other geological/geophysical measurementsDescription: P.D.R recordings made continuously