In order to make clear the geological development of the Japanese Islands, it is necessary to comprehend the geological histories of the adjacent areas. On these lines the recent knowledge on the Cambrian and Ordovician systems of the U. S. S. R. have been introduced by Kobayashi elsewhere in this journal. Silurian is a period of the oldest age of rock formations in Japan. On the Silurian system of China the present writer has already described its geological and geographical features. Here he intends to summarize the Silurian system in the U.S.S.R. from the literatures.
Its description is made as follows:
II. On the Guide books and Geological maps
III. General Remarks on the Silurian System
IV. Outline of the Silurian Stratigraphy. A. Lower Llandovery Stage, B. Upper Llandovery Stage, C. Wenlock Stage, D. Lower Ludlow Stage, E. Upper Ludlow Stage
V. Summary on the Geographical Development References
A distribution map of the Silurian system in the U. S. S. R is inserted on page 26. The Silurian zonation based on the graptolitic fauna is shown in form of a table in comparing with the Bohemian succession.
The regional stratigraphy, igneous activity, Silurian paleontology and others will be outlined as the continuation of this paper.