This review connects the concepts of external eddies and wave motions outside stably stratified/non stratified turbulent interfaces interacting with eddy motions within thin layers (with and without shear), and how these flows have been studied in laboratory experiments (including those at Grenoble) and using numerical simulations. The key physical concepts involve eddy blocking and distortion by stratification and shear, and generation of local and distant wave motions. Applications are described to gfd phenomena and turbulent structure.