Abstract: The terrestrial Neogene sequence of the Menteş Peninsula, located in the Urla section of the Foça Depression, comprises the Middle Miocene Urla Group. The Urla Group unconformably overlies the late Early Miocene Kocadağ Volcanics and consists of sedimentary and volcanic rock units. A sedimentary succession, consisting predominantly of lacustrine deposits, begins with the Bozavlu Formation reflecting alluvial fan sedimentation, continues with the volcano-sedimentary Güvendik Formation deposited on the lacustrine shoreface, and ends with the Urla Limestone. The Güvendik succession frequently contains volcanoclastic density currentlevels in epiclastic (lahar and turbiditic sandstone) and pyroclastic (ignimbrite, base surge, blocky ash flow) facies,reflecting the early period of Menteş volcanism. The Urla Limestone conformably overlies the Güvendik Formation.The Urla Limestone succession contains tuff interlayers with ash fall facies of the Menteş volcanism from bottom totop. Algal bioclastites and oncoidal limestones were deposited at the base and transgressive parts of the limestone succession, formed by waves in the foreshore belt. The Middle Miocene alkali volcanism of the Menteş Peninsula is represented by the Menteş Volcanics and the Ovacık Basalt. Menteş volcanism, which yields products in the trachyte rhyolite composition range, consists of pyroclastics, composite lava domes and dome-flows. The pyroclastic sequence starts with unwelded ignimbrites containing accidental lithics derived from the Ovacık Basalt, and continues with  successive levels of blocky ash flow and base surge. Menteş volcanism evolved in the lake where the Güvendik and Urla Limestone units were deposited. Basic volcanism, which developed laterally to the Menteş acidic volcanism, continued to be active intermittently from the beginning of Urla Limestone deposition to the last stages.