A qualitative model is proposed whereby foot point exchange diffusion of open field lines from a solar active region may have led to the formation of a coronal hole and a corotating stream of fast solar wind. The solar wind speed changed from fast back to slow when the coronal hole was later disrupted by the emergence of a new active region. A corollary of this model is that a corotating interplanetary field line may have both fast and slow solar wind at different places along its length.