The idea that backflow along the coast is necessary to produce the by now well documented meandering of a baroclinic two-layer boundary current in geostrophic balance (Margules current) is explored. A very simple model assuming conservation of potential vorticity in a geostrophic flow yields separation only for a range of low densimetric Froude numbers, Fr=u1/c1. Although the limiting Fr of 0.3 in the present zeroth order model does not agree well with the observed limit Fr=0.7--0.8, we feel the model offers an attractive explanation of some of the observed behaviour of a geostrophic boundary current. ¿American Geophysical Union 1987