Of all the economic minerals that exist on or below the sea-floor only the fuels (oil, gas and coal) and the detrital deposits hold out any positive gain for the immediate future. The location and examination of each type of deposit requires the application of some branch of physics to the geological situation. For oil and gas prospecting, geophysical techniques (seismic, gravity and magnetic methods) have been long established, but exploration for detrital minerals requires a new approach to the subject. It is probable that partial solutions to the problem can be provided by each of a wide variety of physical considerations: the sum total of these (hydrodynamics, acoustics, electrics and magnetics) would give a reasonable description of the deposit.