  Next generation neutrino experiments will push the limits in our
understanding of astroparticle physics in the neutrino sector to energies
orders of magnitude higher than the current state-of-the-art high-energy
neutrino experiment, IceCube. These experiments will use neutrinos to tell us
about the most extreme environments in the universe, while simultaneously
leveraging these extreme environments as probes of neutrino properties at the
highest energies accessible in the foreseeable future: $E\sim10^9$ GeV. At
these energies neutrinos are readily absorbed in the Earth. Assuming an
isotropic distribution, by looking at how the flux varies as a function of
angle through the Earth, we show that it is possible to extract the
$\nu_\tau$-$N$ cross section with precision at the $\sim20\%$ level ($1\sigma$
assuming Wilks' theorem) given $N_{\rm events}\sim100$ events.
