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74 [Vol. 21,

14. Concept of in 5. Time Scale of the Diluviwm and the Relation among various kinds of Time in Historical Sciences.

By Teiichi KOBAYASHI. (Comm.by H. YABE, M.I.A., Jan. 12, 1945.) Diluvium inclusive of Alluvium is a special instant, i. e., a special zone-time of the eon, in which the time-scale of Historia naturalis merges with that of Historia civfilis. From the geological point of view it can be said that it is a unique zone-time of which the internal structure is exposed. Fight estimations for the length of the Ice Age1) published from 1863 to 1914 varied widely from 0.1 to 0.8 million . Since then, it has become possible, through the glaciological method, to make a reliable estimation. Many now consider the duration to be from 0.8 to 1 million years. At least %t is beyond doubt that the period, which Le Conte once called an in his proposal for a P s?Jchozoic era is neither an era nor even a period. It {,acted o more than a million years, or a single zone-time, while the period, the neat order, covers some GJ million ycas. because such great discrepancy in tine-length easily leads to confusion in the ge~lo •ists' concept of thne, I think, in agreement with Sch_uclert and others, it is anpropriate to elin',in`e e the Qaater?ary from the of periods in Geclogy. There is further the, definite reason foi• its elimination. The classification of the Phanerozoic eon is of coarse based on the trans- formation of biota which was very gradual in the transition from to Pleistocene as thoroughly ascertained by the percentage method of study on mollus:;ans, for'.ninifers and other animals and plants. The most notable change in the h'.ota is perhaps the advent of the Hominidae of which however it is said that Accordingto Huxiey the ddTeroncebotween the hihe st and bwest apes are far more marked than those separating iVkand the anthropoid apes."2) Puckland proposed Diluvium in 1.8283', pror to Lyell's Pleistocene in 1839. The diluvial zone-time ( dt rP, o~~more shortly, Diluvium, is I think the best substitute for the invalidated Quaternary period. Put the should be re-defined to include the Alluvium on one hand and itself in turn to be included in the Tertiary period on the other, because the Alluvium can be taken for the fourth interglacial and its duration is estimated to cover only about 25.000 years, i. e. roughly one-fortieth of the length of the Diluviurn, and further- more, because Diluvium is but the last zone-time of the Tertiary period.

1) H. F. Osborn (1915;, Men of the Old Stone . New York. 2) Zittel-Eastman's Text-Book of Palaeontology, vol. 3, p. 283. 3) A. K. von Zittel (1991), of Geology and Palaeontology, translated by M.M. Ogilvie-Gordon. London. No. 1.] Concept of Time in Geology 5. 75

The Diluvium is however a unique zone-time or an instant in the Phanerozoic eon which can be classified into glacial and interglacial stages, as well as into cultural stages and phases in human evolution. The Hominidae include four genera and nine species, three of which are well-known Pithecanthropus erectus of Java, Sinantropus pekin- gensis of Chaokouchuan and Eoanthrops dawsoniana of Piltdown. It is thought that they lived at sometime between 1 and 0.5 million years ago. From 0.2 to 0.3 million years later appeared Homo heidelber- gensis, the oldest of Homo, which genus includes in addition nean- dertalensis, rod esiensis, solensis and sapiens. Cro Magnon was the forerunner of Modern man who appeared on the scene only 0.25 million years ago and racial variation of H. sapiens has taken place only since then. This is perhaps the speediest example of transformation in Biota provided by Nature. Unfortunately their skeletons occur so uncommonly that they cannot be used as time-indices. Though material remains in are more common, world- wide correlation of cultural stages is a difficult matter, because the development of culture varies so greatly. Some primitive races of today indeed are not very far removed from the Stone Age. Glacia- tion provides the best key fog the classification of the Diluvium but it can only be applied to the glaciated regions. It has been therefore frequently inevitable for geologists to use the term, Plio-Pleistocene. The Diluvium can be classified roughly in only those parts of the world where higher mammals occur ; morphological and stratigraphical analyses tell the succession of geological events in a certain limited area, but as doted in a preceding paper of this series it is evidently a contradiction if they are used for correlation in very extensive region. Thus time is localized in Diluvium. Cosmopolitan species or genera which define world-instants are, though not many, known in the Fo-Pa ae~Dzoic era. A notable example is the dynasty of graptoltes. In the era and even in the older Tertiary period the zones of ammonites or other fossils scattered over large provinces. But nevertheless locali atio: of geologic time through the Phanerozoic eon can hardly be over loeked its a general tendency. This localization of fossil-time implies a differentiation of geographical provinces and ecological environments for Biota. These differentiations are well reflected in the increasing variation of rock- facies. These as a whole imply most probably the increasing ten- dency of relief of the earthcrust which is verified by the increase of the rate of sedimentation. In an estimation made in North America the difference of the rate among the Palaeozoic, Mesozoic and Cainozoic sediments are roughly in the ratio of 1:2 : 51'. It is certainly inter- esting to see the general tendency of the hemera to become localized as time proceeds in Historia naturalis, in contrast to Historia civilis in which local time became confluent and at length man arrived at world-time.

1) A. Knopf and others (1931), The Age of the Earth. Bull. 80. Nation Research. Council, Washington, D. C. 7€ T. KOBAYASHI. [vol. 21,

Returning to the classification of the Diluvium, it is now generally divisible into eight stages with, reference to glaciations in Europe and North America, though there are differences of moderate degree in the estimation of the absolute as well as relative lengths of the stages. There is however general agreement in the correlation of these stages with the culture stages as well as with the phases of human evolution. The fourth interglacial stage is the Alluvium which can be divided into culture stages and historical ages. The most accurate record of time is of course given by philological documents but these go back no more than several thousand years. Even the oldest manuscript in the Sumer Civilization is said to be of about 3000 to 3500 B. C. The difference in estimation in this case is 500 years. Since then the tune-scale gradually becomes acurate more and more till one reaches to the concept of instant now we have. In the New and Old Stone Ages the scales are generally marked at intervals of from 500 to 1000 years and 10,000 years respectively, while 25,000 years is taken as the minimum unit in the estimation of the glacial and interglacial stages. Table showing the relation among various kinds of Historical Time. No. 1.] Concept of Time in Geology 5. 77 Thus, for the cognition of time there are various methods, philo- logical, archaeological, anthropological, pal ontological glaciological, stratigraphical and mineralogical. The length of a duration is obtained by some of them while arch eism of an age by some others as shown in the table inserted here. The accuarcy of these kinds of time varies widely. Modern Age is an instant in the Diluvium which in turn is an instant in the Phanerozoic eon. The zone-time is the medium in our concept between a time-unit in the Diluvium which is instantaneous on one side, and a geological period or a still longer until of Geological age which is almost endless on the other. In the Diluvium the scale of time gradually gains in accuracy. Roughly speaking, the scale is marked off at every 105 years or longer in its older part but the intervals get shorter until the scale attains units of 102 years in the early part of the historical age. Later it becomes more and more accurate till the concept of instant becomes really a point of time in our own age. In the rest of the Phanerozoic eon there is a great difference in the length between the zone-time and the period, but if time length may be conceived as being capable of expression by repeated tripata- tions among the era, period, , age and zone-time in the seven units of the geological age including eons and eon, may be roughly expressed by the formula 3~-3x 10". The relation of length among the period, era, eon and eons was discussed in the first article in this series of papers''.

5) It must be kept in mind however that a long period is about three longer than a short one whereas a long zone-time is about nine times as long as the short one.