Cruise inventory

Surveyor 71/1 Leg 2

Cruise summary report

Cruise Info. 
Ship nameSurveyor
Cruise identifier71/1 Leg 2
Cruise period1971-03-09 — 1971-03-28
StatusCompleted
Port of departureStornoway, United Kingdom
Port of returnStornoway, United Kingdom
PurposeResearch
ObjectivesTide Gauges - Geology and geophysics on the Hebridean Shelf and on the Rockall Plateau

Aims:
1. Seismic reflection studies across the Rockall Plateau and Trough.
2. Total magentic field measured throughout except during station work.
3. Accurately measure noise levels in both the Flexotir and NIO array at different speeds and at different stays both for comparative purposes and to provide data useful in hydrophone design.
4. To reconnoitre outcrop areas, detected by seismic profiles, for detailed evidence of structure, bedding, etc., in preparation for drilling in summer 1971.
5. To compare the living faunal distribution with that deduced from the biogenic carbonate fraction of the sediments and to investigate the processes involved in its production.

Narrative
Off Barra head the PDR fish, airgun and hydrophone arrays were streamed. Bad weather and equipment problems delayed profiling. Seismic reflection profiling undertaken to obtain traverses over the northern and southern parts of the Hatton-Rockall Bank, the continental margin and the Rockall Trough. 1400 miles of seismic profile was obtained including 1200 miles on the Rockall Bank and Plateau. Stations 59-69 grab samples at 5 mile intervals across the Rockall Bank; 70-77 grab and dredge samples down eastern edge of the Bank; 78-105 grab stations. At each station 2 grab samples were normally taken. If there was shelly material present then the rock dredge was used. NIO transistored precision-echo-sounder system was used.

Results:
1. Samples of living and dead benthic fauna were obtained from 47 stations.
2. 1400 miles of seismic profile was obtained including 1200 miles on the Rockall Bank and Plateau.
3. Total magnetic field continuously recorded.
4. Noise levels of the NIO 200ft array and Flexotir 60m array were simultaneously recorded.
Chief scientistDavid G Roberts (National Institute of Oceanography)
Cruise reportSurveyor 71/1 Leg 2 cruise report surveyor_feb71.pdf — access key 'C' (0.77 MB) 
Ocean/sea areas 
GeneralNorth East Atlantic Ocean (limit 40W)
Track chartsSurveyor 71/1 Leg 2 cruise track — surveyor_feb71track.pdf (0.06 MB) 
Measurements 
Biology and fisheries 
Sediment trapsQuantity: number of stations = 47
Description: bottom sediment samples collected
Geology and geophysics 
DredgeQuantity: number of stations = 47
Description: benthic faunal samples taken at each station
GrabQuantity: number of stations = 47
Description: benthic faunal samples taken at each station
In-situ seafloor measurement/samplingQuantity: number of stations = 47
Description: bottom sediment samples collected
Multi-beam echosoundingQuantity: number of measurements = 1
Description: acoustic tests
Multichannel seismic reflectionQuantity: track kilometres = 2253
Description: seismic profiling traverses
Magnetic measurementsQuantity: number of measurements = 1
Description: total magnetic field