The discrepancies between the geological and the absolute geochronolo gical data are so marked and fundamental that one is completely justified in treating the "Upper Pre-Cambrian enigma" as one of the most acute unsolved problems of modern geology. The difficulties entailed in elaborating the Upper Pre-Cambrian geochronology might necessitate a discussion of the problem of the constant duration of the terrestrial day and the terrestrial year, and their possible variation in the course of geological history, i. e., the existence during terrestrial history of cycles or periods differing in the velocities of the Earth's rotation about its axis and its revolution about the Sun.
There are certain indications that Upper Pre-Cambrian is an instance of a completely separate, independent cycle in the Earth's development, being the longest known cycle.
7. The relationship between the climatic periodicity and that of the geological processes themselves (primarily diastrophism) has hardly been studied. The well-known formula involving a definite relationship between exogenous and endogenous phenomena (for instance, the dependence of large-scale glaciations upon orogenetic stages) needs considerable revision. There are reasons to assume that both groups of phenomena (endogenous and exogenous) are due to the same general extraterrestrial causes, i. e., to factors of a cosmic nature. However, in the subsequent development of events the mutual or, more frequently, unilateral influence of certain phenomena on other phenomena must have gradually manifested itself, and become very strong in certain cases. For instance, the grouping of continents and their configuration, and the uplifting of large continental areas in the form of mountain ranges or plateaus may have facilitated the development of glacial covers, although in themselves they were not the causes of glaciation. These causes must be sought in a general decrease of the mean annual temperature on the Earth's surface due to cosmic factors, probably the same factors as those that must have caused disturbances in the subcrustal portions of the planet and deformations of its solid shell.
8. The existence of prolonged stages or periods in the development of the Earth's structure, of 150 to 200 million years has been suggested (Belousov, 1951). It follows from the above statements that these periods agree closely with the "cosmic" winters," i. e., they correspond to the galactic year. Their nature should apparently be studied from this approach.
A few years ago (Lungersgauzen, 1956, 1957) the important role played in the Earth's history by the orogenic and magmatic cycles comprising periods of 38 to 45 million years was noted. The analysis was performed by superimposing on the geochronological background peaks corresponding to the most important geological events such as orogenic manifestations, intrusive and effusive magmatism, maxima of the transgressions and regressions of the sea, etc. This processing of factual data yielded closely conforming numerical results for the eastern and western parts of the Siberian platform, Altai, the Eastern Balkhash area, certain parts of the Russian platform, the southern Urals, etc.
Geological periods of 38 —45 million years are equal to half of the astronomers' "draconitic period" (about 90 million years), i.e., they can be causally related to the oscillations of the solar system with respect to the galactic plane during the revolution of the Sun in its galactic orbit. The self-evident relationship between climatic variations in the past geological epochs and the above diastrophic cycles has not yet been given special consideration in the literature; studies of this relationship constitute one of the most important tasks of paleoclimatology.
9. The data accumulated during recent years and the probable relation ship between geological events and the Earth's evolution as a cosmic body call for critical revisions of geochronology and stratigraphy. Questions have been raised concerning the necessity of correcting the positions of the principal boundaries between the geological groups (eras) and even systems (periods). The solution of this problem is facilitated by the fact that the geological eras practically coincide with the galactic year, According to the new approach, boundaries of eras (or galactic years) may be fixed by stages of the most violent (global) perturbations, such as the great glaciations, involving both the Earth's solid shell (Lipalian, Caledonian, Hercynian, and Alpine orogenic cycles) as well as the hydro sphere and the atmosphere. Some of the probable corrections for the general geochronological scale are already essentially obvious. Such corrections include the differentiation of the Lower Paleozoic as an independent era, expansion of the Mesozoic era, and modification of the lower boundary of Anthropogen (this boundary should be drawn under the Upper Pliocence, which is thus excluded from the Neogene period).