  Examples of heavy mineral placer deposits are presented in which wave
reflection, refraction, diffraction and resonance would appear to have played a
major concentrating role. Their geometry is compared with the computer
generated patterns predicted for the reflection, refraction and diffraction of
surface waves moving over fairly simple, idealised bathymetries. Much of this
work is founded on the idea that similar sediments document equivalent (or once
equivalent) flow-tractional environments.
  Most of the examples could be satisfactorily explained in this fashion. It
may therefore be possible to ignore the exact physics of the boundary layer,
longshore and tidal return currents etc. at the scale on which these examples
occur, leaving the way open for the qualitative use of results obtained using
the likes of the mild slope wave equation. A ``Monte Carlo'' approach based on
wave induced tractions should therefore succeed in elucidating presently known
heavy mineral placer deposits and, consequently, in predicting other deposits
which remain as yet undiscovered.
