The Middle Miocene sediments outcropping between Szydłów and Brzeziny are represented by the Pińczów Beds and the Chmielnik Beds. The Pińczów Beds are developed as the Heterostegina sands with intercalations of red algal limestones. These sediments contain numerous fossils of foraminifera, bryozoans, bivalves, ostracods, echinoids, crustaceans and corallinacean red algae. Foraminifera (Amphistegina, Heterostegina, Orbulina suturalis) point to the early Badenian age of the Pińczów Beds. The Chmielnik Beds contain mainly organodetritical limestones, which are composed mainly of grains eroded from the Badenian red algal limestones. The organodetritical limestones contain pebbles and blocks of microbial-serpulid limestones, Abra limestones, marls and rare lenses of quartz sands. Numerous pectenids, other small bivalves, gastropods, foraminifera and rhodolites occur here. The fossils point to mainly Anomalinoides dividens Zone. New literature data show that this zone, commonly accepted as diagnostic for the beginning of Sarmatian, is diachronic. Therefore, the Badenian-early Sarmatian age is suggested for the Chmielnik Beds. The presence or absence of normal-marine biota as an age criterium for the Badenian-Sarmatian boundary, the commonly accepted idea for the brackish Sarmatian basin of the central Paratethys has been challenged recently. Both Badenian (not redeposited) and Sarmatian fossils occur in the Chmielnik Beds. Therefore, part of deposits in the Szydłów area assumed so far to be of Sarmatian age, can in fact represent late Badenian age.