  We point out a dramatic new experimental signature for a class of theories
with extra dimensions, where quarks and leptons are localized at slightly
separated parallel ``walls'' whereas gauge and Higgs fields live in the bulk of
the extra dimensions. The separation forbids direct local couplings between
quarks and leptons, allowing for an elegant solution to the proton decay
problem. We show that scattering cross sections for collisions of fermions
which are separated in the extra dimensions vanish exponentially at energies
high enough to probe the separation distance. This is because the separation
puts a lower bound on the attainable impact parameter in the collision. We
present cross sections for two body high energy scattering and estimate the
power with which future colliders can probe this scenario, finding sensitivity
to inverse fermion separations of order 10-70 TeV.
