The History of the Aptian Stage Stratigraphy and Ammonoids of the Central Part of the Northern Caucasus Studies. Paper 1. 19th Century to 1969

<jats:p>The offering paper covers the history of the Aptian stage stratigraphy and ammonites studies of the central part of the Northern Caucasus, which was subdivided by the author into five stages. The first (mid-to-late 19th century), second (1901–1951) and third (1952–1969) stages are reviewed. The first is associated with the beginning of research in the region, at this time the attempts of the stage and substage dividing were made. The second stage is associated with the activities oftheGeological Committee, atthis periodthe firstzonalschemeswere elaborated.During the third stage the works of the Lower Cretaceous squad of the integrated Crimean-Caucasian Expedition made the main contribution, during this time numerous Aptian ammonoids were described and a lot of biostratigraphic schemes were elaborated.</jats:p>