The Bostobe Formation (Kazakh: Boztóbe svıtasy) is a geological formation in Qaraghandy & Qyzylorda, Kazakhastan whose strata date back to the Late Cretaceous (Santonian to early Campanian stages, approximately 85 Ma). The sandstones and claystones of the formation were deposited in estuarine, fluvial-lacustrine and fluvial-deltaic environments. Dinosaur remains are among the fossils that have been recovered from the formation. The formation is about 45 metres (148 ft) thick and consists primarily of clay with interbeds of sand, representing an estuarine environment.