  We point out that the presence of bulk neutrinos in models with large extra
spatial dimensions can lead to observable flavour specific deformations in the
spectra of extreme high energy cosmic neutrinos. These deformations are due to
the spin precession of the high energy neutrinos in the background magnetic
fields via electromagnetic interactions. Measurements with existing and
proposed neutrino telescopes which are meant to detect high energy neutrinos
can therefore provide a novel way to probe the size of extra hidden dimensions.
We qualitatively illustrate the flavour suppression due to the Earth, Sun and
intergalactic magnetic fields. An observable consequence of this precession
could be an angular asymmetry for the extreme high energy neutrinos from the
atmosphere and flavour specific deformations of the intergalactic neutrinos.
