Horizontal Air Showers: Neutrino Physics at AUGER  

It is well established by experiment that the cosmic ray spectrum 
extends beyond primary energies of $10^{20}$ eV.  In all production 
models neutrinos comprise a part of the high energy cosmic ray flux.  
The Pierre Auger cosmic ray detector, under development, has the 
potential to study horizontal air showers intitiated by high energy 
neutrinos.  In particular, a determination of the spectrum of high energy 
$\tau$--neutrinos may be used to establish the validity of the 
GZK cutoff.