Morawan Formation

The Morawan Formation is a Chattian age siliceous marine geological formation of the Oligo-Miocene Japanese Kawakami Group of eastern Hokkaido prefecture.^[1][2][3] The formation is fossil rich and contains source units where toothed baleen whales (Aetiocetidae) and Desmostylians have been discovered.^[4]

Morawan Formation
Stratigraphic range: Chattian
Type	Formation
Unit of	Kawakami Group
Sub-units	unnamed, Kamirawan, Lower Hard Shale, Middle Hard Shales, Upper tuffaceous silstone
Underlies	Kiroro Formation
Overlies	Hombetsuzawa Formation
Thickness	500 m (1,600 ft)
Location
Region	Hokkaido
Country	Japan

The Morawan Formation is a very siliceous unit containing hard platy shales interbedded with tuffaceous mudstones and sandstones, and some pumice. The unnamed lower member is a hard platy shale alternating with beds of tuffaceous mudstones and sandstones, the Kamirawan member is a tuffaceous sandstone with pumice, the Lower Hard Shale is a very siliceous hard shale with tuffaceous sandstones and mudstones, and the Middle Hard Shales and the Upper tuffaceous siltstone are similar.^[5]

Fossil species from the Morawan Formation include:

• Ashorocetus eguchii
• Morawanocetus yabukii
• Aetiocetus tomitai
• A. polydentatus