  Jamming occurs in granular materials, as well as in emulsions, dense
suspensions, and other amorphous, particulate systems. When the packing
fraction $\phi$, defined as the ratio of particle volume to system volume, is
increased past a critical value $\phi_c$, a liquid-solid phase transition
occurs, and grains are no longer able to rearrange. Previous studies have shown
evidence of spatial correlations that diverge near $\phi = \phi_c$, but there
has been no explicit spatial renormalization group (RG) scheme that has
captured this transition. Here, I present a candidate for such a scheme, using
a block-spin-like transformation of a randomly vacated lattice of grains. I
define a real-space RG transformation based on local mechanical stability. This
model displays a critical packing fraction $\phi_c$ and gives estimates of
critical exponents in two and three dimensions.
