  We numerically analyse the landscape governing the evolution of the
vibrational dynamics of hard disk glasses as the density increases towards
jamming. We find that the dynamics becomes slow, spatially correlated, and
starts to display aging dynamics across an avoided Gardner transition, with a
phenomenology that resembles three dimensional observations. We carefully
analyse the behaviour of single glass samples, and find that the emergence of
aging dynamics is controlled by the apparition of a complex organisation of the
landscape that splits into a remarkable hierarchy of minima as jamming is
approached. Our results show that the mean-field prediction of a Gardner phase
characterized by an ultrametric structure of the landscape provides a useful
description of finite dimensional systems, even when the Gardner transition is
avoided.
