VOLGIAN STAGE

major and uppermost division of Jurassic rocks (i.e., those formed from about 152 to 144 million years ago) in continental and Arctic regions of Russia. Elsewhere, the Purbeckian stage is generally recognized as the uppermost Jurassic stratigraphic unit. Two primary divisions of the Volgian, Upper and Lower, have been recognized on the basis of well-developed ammonite faunas. Volgian faunas appear to be restricted in geographic distribution.