  We study the avalanche dynamics of a pile of micron-sized silica grains in
miniaturized rotating drums filled with water. Contrary to what is expected for
classical granular materials, the avalanches do not stop at a finite angle of
repose. Below an angle $\theta$\_c, we observe a creep regime where the piles
slowly flow until they become flat. In this regime, the relaxation is
logarithmic in time and is slower when the ratio between the weight of the
grains and the thermal agitation is increased. We propose a simple 1D model
based on Kramer's escape rate to describe this flow.
