  We study the response to shear of a one-dimensional monolayer embedded
between two rigid plates, where the upper one is externally driven. The shear
is shown to excite ``shearons'', which are collective modes of the embedded
system with well defined spatial and temporal pattern, and which dominate the
frictional properties of the driven system. We demonstrate that static
friction, stick-slip events, and memory effects are well described in terms of
the creation and/or annihilation of a shearon. This raises the possibility to
control friction by modifying the excited shearon, which we examplify by
introducing a defect at the bottom plate.
