  We find that a column of glass beads exhibits a well-defined transition
between two phases that differ in their resistance to shear. Pulses of
fluidization are used to prepare static states with well-defined particle
volume fractions $\phi$ in the range 0.57-0.63. The resistance to shear is
determined by slowly inserting a rod into the column of beads. The transition
occurs at $\phi=0.60$ for a range of speeds of the rod.
