Distance of the star clusters from the wall (Δd_c–w) as a function of age. Clusters, most probably created in the wall of the supershell are shown as black circles, other young clusters (age < 120 Myr) are empty triangles. Old clusters (age > 120 Myr) are grey squares. The dashed line shows the distance travelled at a speed of 10 km s⁻¹ during the age of the cluster. Dotted lines delineate ages of 30 and 60 Myr.