Geophysical and Sampling Survey 1968/5: Sea of the Hebrides and The Minch (20/Sep/1968 to 03/Nov/1968)
CP2 Regional Sea Boundaries: Minches & Western Scotland, Scottish Continental Shelf, Offshore 1:250k: Argyll, Great Glen, Lewis, Little Minch, Malin, Peach, Sutherland, Tiree, Offshore 1:500k: Central Rockall Basin, North Rockall Basin, SeaVoX Sub-Ocean: INNER SEAS OFF THE WEST COAST OF SCOTLAND, NORTHEAST ATLANTIC OCEAN (40W)
This sampling and geophysical survey has been carried out by British Geological Survey (BGS) for BGS, the survey took place in September to November 1968 in the Sea of the Hebrides and the Minch on board the RRS John Murray. These purpose was to collect data to investigate the sub-surface geological structure and sea-bed geology additional geophysical observations were planned for the return passage to Plymouth including a detailed survey of a small area in the southern Irish Sea (see 1968/Passage survey for details). Sea floor data were collected using echo sounder. Sub-bottom profiling data were collected using sparker and sidescan sonar. Gravity meter and magnetometer data were collected. Sample data were collected using shipek grab, sediment dredge,rock dredge and scuba diving. These data are archived by BGS. Technical details of the survey are contained in BGS report WB/MG/68/28.
For more detailed information on the acquisition equipment and data collection techniques, operational standards, data processing methods and quality control procedures used on this survey see the Report of Survey/Cruise Report and associated documentation where available. The information available may vary depending on the age of the survey. Data are checked and loaded to the BGS Coastal and Marine data management system following BGS marine data management procedures. Report: McQullian, R, Eden, RA, and Tully, MC. 1968. Geophysical and Geological Investigations in the Sea of the Hebrides and Minch. MGU Project 68/05. (IGS Report No 28). Positioning systems: Two Decca Mk 12 receivers one operated on Decca Chain 3B/MP and the other on Decca Chain 6C/MP. In general and particularly at night the 3B signal was more stable that the 6C signal. Niether was completely satisfactory and the positioning was suplemented by radar and visual sitings. The positions were logged manually every 10 minutes. Echo sounder system: Kelvin Hughes MS 38 Precision Depth Recorder. Sparker system: 3-candle sparker array unit with a EG&G 16-element hydrophone array type 263A. The sparker was run at 1000 Joules, a 1 second firing rate and a print sweep of 0.5 seconds. External and internal band-pass filters were applied usually in the 100-800kHz range. Pinger system: EG&G 5kHz pinger was used with a single element EG&G type 262 G hydrophone. Side-scan system: EG&G side-scan sonar. Optimum setting 500ft scan. Gravity meter: Askania Sea Grvaity Meter type Gss-2 No 11 Magnetometer: Varian proton magnetometer. Report: McQullian, R, Eden, RA, and Tully, MC. 1968. Geophysical and Geological Investigations in the Sea of the Hebrides and Minch. MGU Project 68/05. (IGS Report No 28)
Echo Sounder, Gravimeter, Magnetometer, Pinger, Sidescan Sonar, Sparker
Corer: Sediment Gravity, Diver Collected, Dredge: Rock, Dredge: Sediment or Shell, Grab: Shipek
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