  Utilizing only the vertical muon intensity of the Gaisser parameterization of
the muon flux at the surface and propagating this energy spectrum underground
according to statistical ionization and radiative energy losses, it is possible
to calculate the underground muon intensity Crouch curve. In addition, the
primary spectral index of the Gaisser parameterization can be adjusted from
$E^{-2.7}$ to $E^{-2.643}$ simply by minimizing the deviation from the Crouch
curve. For chemical compositions other than standard rock, the propagation of
the spectrum underground can be repeated with a different muon energy loss in
the material. The resulting underground muon intensity curve represents a
consistent conversion of the Crouch curve to the local rock, fully accounting
for the energy dependence of the muon $dE/dx$.
