BGS has provided an invaluable contribution to the successful petroleum exploration of UKCS since exploration commenced in the early 1960s. Legislation provides that all data acquired by industry be lodged with Government who have appointed BGS as custodians. BGS maintains the National Hydrocarbon Core Store in Edinburgh. Their Hydrocarbons Unit prepares for Department of Energy detailed prospectivity reviews which provide the basis for licensing policy and reserves estimates. A systematic programme of sea-bed mapping commenced in 1967 and will be completed in 1990 when 328 geophysical and geological maps will have been published. BGS also monitors seismicity offshore.