  We describe experiments that probe the evolution of shear jammed states,
occurring for packing fractions $\phi_S \leq \phi \leq \phi_J$, for frictional
granular disks, where above $\phi_J$ there are no stress-free static states. We
use a novel shear apparatus that avoids the formation of inhomogeneities known
as shear bands. This fixed $\phi$ system exhibits coupling between the shear
strain, $\gamma$, and the pressure, $P$, which we characterize by the `Reynolds
pressure', and a `Reynolds coefficient', $R(\phi) = (\partial ^2 P/\partial
\gamma ^2)/2$. $R$ depends only on $\phi$, and diverges as $R \sim (\phi_c -
\phi)^{\alpha}$, where $\phi_c \simeq \phi_J$, and $\alpha \simeq -3.3$. Under
cyclic shear, this system evolves logarithmically slowly towards limit cycle
dynamics, which we characterize in terms of pressure relaxation at cycle $n$:
$\Delta P \simeq -\beta \ln(n/n_0)$. $\beta$ depends only on the shear cycle
amplitude, suggesting an activated process where $\beta$ plays a
temperature-like role.
