  We study the deflection by gravity of a circular elastic disk deposited on a
rigid support. The axisymmetric deflection induces a compressive orthoradial
stresses which leads to a wrinkling instability above a critical threshold of
the dimensionless gravity force. We study this instability by a combination of
experiments, numerical simulations and analytical tools, with a particular
focus on the role of geometry. We show that aspect ratio is a crucial parameter
that controls both the threshold of instability and the most unstable mode. The
influence of this parameter on the threshold can be catched by introducing a
new nondimensionalization of the transverse load.
