One of the most striking feature in the X-ray morphology of A 4059 is the bright and cool SW ridge. The SW edge of this ridge appears to be surface across which the temperature and entropy of the gas change significantly with little or no change in pressure. In many ways, this is similar to the ``cold fronts'' that have been observed in many clusters (Markevitch et al. 2000; Vikhlinin, Markevitch & Murray 2001). Here, we will discuss four possible formation mechanisms for this structure.