  Simultaneous rheological and velocity profile measurements are performed in a
smooth Couette geometry on Laponite suspensions seeded with glass microspheres
and undergoing the shear-induced solid-to-fluid (or yielding) transition. Under
these slippery boundary conditions, a rich temporal behaviour is uncovered, in
which shear localization is observed at short times, that rapidly gives way to
a highly heterogeneous flow characterized by intermittent switching from
plug-like flow to linear velocity profiles. Such a temporal behaviour is linked
to the fragmentation of the initially solid sample into blocks separated by
fluidized regions. These solid pieces get progressively eroded over time scales
ranging from a few minutes to several hours depending on the applied shear rate
$\dot{\gamma}$. The steady-state is characterized by a homogeneous flow with
almost negligible wall slip. The characteristic time scale for erosion is shown
to diverge below some critical shear rate $\dot{\gamma}^\star$ and to scale as
$(\dot{\gamma}-\dot{\gamma}^\star)^{-n}$ with $n\simeq 2$ above
$\dot{\gamma}^\star$. A tentative model for erosion is discussed together with
open questions raised by the present results.
