Plain Language Summary The southern slope of the Greater Caucasus mountains is the site of a former rift basin. In order to explain shortening deficits, plate deceleration, and the similar to 5 Ma reorganization of the Arabia-Eurasia collision zone Cowgill et al. (2016) proposed that this basin closed similar to 5 Myrs ago. Within the western Greater Caucasus, at least, careful examination of sedimentological, provenance, and seismic data, however, supports an earlier similar to 35 Ma basin closure age. Basin closure cannot therefore be the driving mechanism for the similar to 5 Ma deceleration of the Arabian plate and reorganization of the Arabia-Eurasia collision zone.