  The origin of the ultra high energy cosmic ray (UHECR) showers has remained
as a mystery among particle physicists and astrophysicists. In low scale
gravity models, where the neutrino-nucleon cross section rises to typical
hadronic values at energies above $10^{20}$ eV, the neutrino becomes a
candidate for the primary that initiates these showers. We calculate the
neutrino-nucleon cross section at ultra high energies by assuming that it is
dominated by the production of p-branes. We show, using a generalized
Randall-Sundrum model, that the neutrino-nucleon cross-section at neutrino
energies of $10^{11}$ GeV is of the order of 100 mb, which is required for
explaining UHECR events. Similar result also follows in other models such as
the Lykken-Randall model.
