Halliday & Matthiessen (2014: 472):
Examples of clauses linked by an ‘adversative’ relation:||| We liked that breed of dog, || but we felt || we weren’t in a position [[ to own one at the time]] . |||||| The solar elevation angle is comparatively low by October, || when the hole was at its deepest, || but is much higher in November, || when the ultraviolet (UV) effect might be stronger at the surface. |||The linker but contains the semantic feature ‘and’, so we do not say and but. For the same reason we do not say although ... but, because that would be a mixture of hypotaxis and parataxis; whereas although ... yet is quite normal – there is no paratactic ‘and’ in yet.