Four volcanic rocks from northern Tunisia and a syntectonic granite from northeastern Algeria were dated by the K—Ar method. The stratigraphic position of the dated rocks is determined mainly by their relationship to biostratigraphically calibrated Miocene tectonism. The K—Ar age of the granite, which is younger than latest Burdigalian and older than Early Tortonian, is 16.8 m.y. (*15.8 m.y. calculated with western decay constants). Rhyodacite at 10.9 (*10.4), rhyolite at 8.8 (*8.3), basalt at 7.3 (*6.9) and adesite at 7.0 (*6.7) m.y. are all apparently younger than Lower Tortonian.