Snapshots from the simulation of \citet{Grudic2021_Associations} showing the formation of an arc structure similar to Barnard's Loop. The left snapshot was taken at a code time of 5.8 Myr, and the right snapshot was taken at a code time of 8.8 Myr. White dots show stars in the simulation, and the color bar refers to projected gas density. Roughly 20 supernovae exploded in the 3 Myr gap, creating an arc roughly 50 pc in radius.