  It is widely believed that star clusters form with low star formation
efficiencies. With the onset of stellar winds by massive stars or finally when
the first super nova blows off, the residual gas is driven out of the embedded
star cluster. Due to this fact a large amount, if not all, of the stars become
unbound and disperse in the gravitational potential of the galaxy. In this
context, Kroupa (2002) suggested a new mechanism for the emergence of thickened
Galactic discs. Massive star clusters add kinematically hot components to the
galactic field populations, building up in this way, the Galactic thick disc as
well. In this work we perform, for the first time, numerical simulations to
investigate this scenario for the formation of the galactic discs of the Milky
Way. We find that a significant kinematically hot population of stars may be
injected into the disk of a galaxy such that a thick disk emerges. For the MW
the star clusters that formed the thick disk must have had masses of about 10^6
Msol.
