The transition into a glassy state of a tapped granular pile is explored in detail using extensive
molecular dynamics simulations. We measure the density and density fluctuations of the ensemble
of mechanically stable configurations reached after the energy induced by the perturbation has
dissipated. We show that the peak in density fluctuations concurs with the density undergoing
the transition. We find that different horizontal sub-regions (“layers”) along the height of the pile
traverse the transition in a similar manner but at distinct tap intensities, demonstrating that at a
given intensity certain regions of the same pile may respond in a glassy manner while others remain
equilibrated. To address this phenomenon, we supplement the conventional approach based purely
on properties of the static configurations with investigations of the grain-scale dynamics, induced
by a tap, by which the energy is transmitted throughout the pile. We find that the effective energy
that particles dissipate is a function of each particle’s location in the pile and, moreover, that its
value plays a distinctive role in the transformation between configurations. This internal energy
provides a “temperature-like” parameter that allows us to align the transition into the glassy state
for all layers, as well as different annealing schedules, at a critical value.