Samples and associated geological data are held at the British Geological Survey for Maritime Coastguard Agency (MCA), Civil Hydrography Programme (CHP), Bathymetric Survey HI1298; Passage of Tiree, Area in SqKm: 1238, (01/11/2011 to 26/10/2012), Standard: IHO S44ed5 Order 1a. Contract: Medium. FY 2011/12. Contractor: NetSurvey.