  It is likely that ultra-high energy cosmic rays contain a significant
component of heavy or intermediate mass nuclei. The propagation of ultra-high
energy nuclei through cosmic radiation backgrounds is more complicated than
that of protons and its study has required the use of Monte Carlo techniques.
We present an analytic method for calculating the spectrum and the composition
at Earth of ultra-high energy cosmic rays which start out as heavy nuclei from
their extragalactic sources. The results obtained are in good agreement with
those obtained using numerical methods.
