The Bukachacha Formation is a geological formation in Zabaykalsky Krai, Russia dating to the Early Cretaceous (Barremian). The tuffaceous mudstones of the formation were deposited in a lacustrine environment. Fossil content The formation has provided fossil insects: Coleoptera Coptoclavidae Stygeonectes jurassicus Trichoptera Phryganeidae Proagrypnia sp. Ephemerida Hexagenitidae Ephemeropsis trisetalis See also List of fossiliferous stratigraphic units in Russia Batylykh Formation, contemporaneous fossiliferous formation of Buryatia References Bibliography Geologic formations of Russia Lower Cretaceous Series of Asia Cretaceous Russia Barremian Stage Mudstone formations Tuff formations Lacustrine deposits Fossiliferous stratigraphic units of Asia Paleontology in Russia Formations