87

GEOIJOOIOÂL CONTEMPORANEIITY AS VIEWED FROM

rr THEORY OF RELATIVITY

(with 8 text figures)

BY H. T. CHAISG.(J)(Geological Survey of China)

The three-dimensional conception of the world is to be replaced

by the four-dimensional one according to Einstein's theory of relativity.Eistein's theory concludes to the space-time continuum: any expression of

time independent of space or of space independent of time would becomemeaning less.

Such four-dimensional conception of the world is quite in agreement

with Chinese old philosophical ideas of Yu-Chou The philosopher

Ohiang-tze (ltH) of the fourth century B. O. said.

"Yn is reality without substance, Chou is duration without beginning

and end."

An early commentary gave the following explanation.

"±1vq1, Ç,i1:t+*ElU""Up, down and the four cardinal directions make Yu, the past,

the present and the future make Chou."

Thus it is clear that Yn means space and Chou time. But inChinese philosophy these two terms ars always combined together; the space-

time continuum was therefore tacitly admitted. As the eminent Japanesegeologist Prof. B. Koto (2) has well said, geology is a four-dimensional

science. We not only make maps and cross-sections, studying the three.dimensional space but also we give important consideration to timo The

question is how and by what method Geological Science can deal with the

four-dimensional world which it proposes to study.

(r) This is the summary of a more extensive paper published in Chinese in "ScienceVol. X, No. 9,

(2) Journ. Tokyo Geol. Soc. Vol. 329, p. 88.

38 Thtliain of the Ooogieai Society of hina

Among the many aims of Geological Science, au important one is to

establish the succession of geological events which occurred upon the Earth,

and to achieve this object it is of the first necessity to rely upon the synchronism

or chronological contemporaneity of geological formations at any distance. For

geologists are not contented with the succession of events on a same spot but

they pretende to be able to establish the chronologial. comiomporaneity of

events on widely distant points on the globe. Without the fundamental

principle of contemporaneity the whole historical geology and especiallypaleogoography would lose all real significance. Of course such contem.

poraneity does exist in reality. The question is only how to safely recognized

it in practice; or whether the methods actually available to geologists aresufficiently adequate to their end.

Time only exist by the successive of events and can not be conceived

independently It is understandable only by the variation in space. Any

event is variable in every direction in the four-diinentional universe, but not

in a uniform way in all directions. Therefore identity of events occurring in

different places can not be taken necessarily to prove their contemporaneity.

Indeed breaks in the physical world are generally local or regional but notnecessarily universal, and the succession of physical breaks in one place is not

necessarily the same as the succession of such breaks in another. hi other

words, similarity in events does not imply contemporaneity in time; nor iscorrespondance in succession the infallible evidence of correspondance in age.

In the theory of relativity, the simultaneity of two lightning strokes

at. two points A and B is only evidenced 1y the perception at the same time, at

the mid-point M between A and B outside the gravitational field and belonging

to the same reference body, because under those specified conditions the lights

starting from A and B must travel to M over an equal distance and with the

same velocity in all directions. If we can assume that geological phenomena

at any part of the world have developed at a uniform rate in all directions

just as light has its constant velocity of propagation, or could we suppose that

their evolution took place parallelly and uniformly with no retardation nor

acceleration in all parts of the world, it may be then possible to take them to

establish geological contemporaneity. But can such assumptions ho justified

by facts?

H. T. Chanq:f.eologiel Conempnraneiti viewed from Theon,' of Rek/ivitî 39

Many criteria have boen used by geologists to prove geological con-

temporaneity, chief among which are lithological characters, stratigraphical

succession, fossil organic contents and tectonic movements etc. Each of these

criteria may bave some significance, but none of them can be taken as definite

proof. And not unfrequently different criteria lead to different conclusions;

it requires then all the geological ingamiity to make compromise or conciliation.

The wonderful development of the modern paleontology hasmade geologists give more and more prevalent Importance to the fossil fauna

and flora as the best criteria on the age of sedimentary deposits. But does

similarity of fossils mean contemporaneity in time? Let us hear the unequi-

vocal opinion expressed by P. H. Huxley (.8).

"They (paissontologists) take it for granted, that deposits containing

similar organic are synchronous - at any rate in a broad sense, and yet thosewho will study the 11th and 12th chapters of Sir Henry De La Bchsremarkable "Researches in theorical Geology" may very easily convince

themselves that even absolute identity of organic contents is no proof of the

synchrony of deposits, while absolute diversity is no proof of difference of

date Edwards Forbes was in the habit of asserting that the similarity of

the organio contents of distant formation was prima facie evidence, not of

their similarity, but of their difference of age; and holding ás he did thedoctrine of single specific center, the conclusion was as legitimate as anyother; for the two districts must have been occupied by migration from one of

the two or from an intermediate spot and the chances against exact coincidence

of migration and imbedding are infinite Whether the hypothesis of single

or of multiple specific centers be adopted, similarity of organic contents cannot

possibly efford any proof of the synchrony of the deposits which containthem

"There seems, then, no escape from the admission that neitherphysical geology nor paleontology, possesses any method by which the absolute

synchronism of two strata can be demonstrated. All that geology can prove is

local order of succession."

(3) T. H, Huxley: Geological contemporaneity and persistent types of life. 86s.

40 PUetmn of the Geological Sociei of China

Altbough not all geologists and pabeontologists go so far as Huxley

ami Forbes, the latter's opinion has however never teen fundamentally invali-

dated. On the contrary sincere geological mind seems to be always obsessed by

the relativity of time correlation upon paleontological evidence. Geikie (4)

wrote: "Strict contemporaneity can not be asserted of any strata merely on the

ground of similarity or identity of fossils." Williams (5) also emphasized on the

impossibility to establish strict contemporaneity among strata of widely sepa-

rated region and that the stratigraphie unit should be system instead of period.

Similar opinion is frequently expressed although more or less clearly by many

other geologists. The best that modern paleontologists can say in defence of

the contemporaneity of similar fauna is that "if path is open and no barriers

exist, widespread migration or dispersal may occur within such short time

limite as to be considered almost homochrenic" (6). In full recognition of

the weight of this argument, we must confess that there still exists widepossibiliti of the non-synchronism of similar fossil contents and we may ask

whether the synchronism of similar fauna or flora claimed by modern paleon -

tology constitute general rule or mere exception.

Let ùs quote again Huxley "But it would have been very much

better for geology if so loose and ambiguous a word as contemporaneous had

beeii excluded from her terminology, and if, in its stead, some term expressing

similarity of serial relation, and excluding the notion of time altogether, hasbeen employed to denote correspondance in position in two or more series of

strata".Thus Huxley as well as William went so far to want to banish the

term "comtemporaneity" from geological literature or to attach to it no signifi-

cance of time at all. 'i'his is in fact a conclusion which can be easily deduced

from the principle of riativity.

Frein the principle of relativity, ii is clear that I. time can notbe understood independent from space and 2. all variations being relative

to the space-time continuum, there can be no measure of time independent of

space. To base geological synchronism ou fossil organic rmaius is evidently

() Geikie: Text book o! geology 3rd ed. 1893, p. 6o8.H. S. \Villiams: Bearing f sorne few paleontological facts on nonienclation andclassification of sedimentary formation. Bull. Geol. Soc. Am. Vol. XVI, p. 138, etc.A. W, Grabau: Principies of Stratigraphy 1913, p. 1125.

H. T, Chan.g:Geologicai Oontenioraneiiy viewed from Theory of Relativity 41

against this principle of relativity of time, sh the fossils are taken as anindependent measure of time in all parts of the world while their variation isessentially dependent of space. This makes also very doubtful the palogeo-graphic conclusions which presuppose geological synchronism.

Some examples of recent determinations will show bow much widelyvariable it may be. The Chi hsia limestone of near Nanking has been attri-buted to Lower Carboniferous by Frech according to its fossil corals andrecognized as such by other pabeontologists until recently Prof. Hayasaka(7) comes to assign it to Permian on the basis of another cora1 And thisimportant uplift in age has been so to say predicted by the field stratigraphicalobservations (8). The Tainan limestone formerly considered as Ordovicianhas been recently assumed by Mr. Yamanali (9) to extend in age from Ordovi-cian to Lower Carboniferous. This is not because there was any seriouserror in the fossil determination of the Tsinan limestone, but his point is thatthe same fossils living in Ordovician time in other parts of the world maycontinue to li'e in lower Carboniferous time in China. The Kaohi limestonef rmation of the Pagoda hill near Taj An in Shantung was first determined onthe basis of its fossils as lower part of Chaumitien limestone (Upper Cam-brian) by Walcott. But Y. O. Sun does not agree with Walcott and separatesthis formation from the Ohaurnitien ii,nestone under a new name, the "Kaohi-shan formation", which he regards as the uppermost part of the UppertJambrain (10) and this is again confirmed by the finding of a graptolite (11).Then how to concihiate it with the occurrence of the Nothozoe (12) which is aLower Cambrian fossil in North America? (13) Similar instances abund toprove the great difficult of time correlation. The question does not lie somuchon the right choice of any particular index fossils as on the intrinsic value ofthe method of correlation itself. The error seems to simply result frommeasuring time independently of space or in other words forgetting thatgeology is a four-dimentional science. It is a natural conclusion from theprinciple of relativity that fossils good to indicate geological age oratratigra-phical order in one place can not be taken tO recognize the same age in allother parts of the world.

Hayasaka: Onthe geological age of the Taj Hsia Shan limestone in Nariking mountains,China, Jour. Geog. Soc., Tokyo, Vol. 37, p. 69, 1925. Hayasaka: On the distribution ofGeuns Tetrapara in China, Jour. Geog. Soc.. Tokyo, Vol. 37, p. '54, 1925.C. Y. Hsieh and Y. T. Chao: Geology of 1-chang, Hsing Shan, Tzekuei & Pa Tung districtc,W. Hupeh. Bull. Geol. Surv. China No. 7, 1926, p. 52.Jour. Tokyo Geol. Soc. No. 382-384.

('ok's) Y. C Sun: Cambrian fauna of North China. p. I.(12) Peking High Normal Sehool for Women: Geological report of Shantung.i3) A. W. ('.rabau: North American index fossils, Vol. ii, p. 375.

42 Balietin of thc Geological Societ,i of China

If we now come to the palogegraphy we can iot help being sceptic

in many cases about the reality oî the exactly synchronous existence of land

and sea as palogeographers like to show by their interesting maps. To make

areas of similar marine fauna contemporaneous areas or seas bearing similar

land animal or plants contemporaneous continents is to consider the geogra-

phical distribution of the fauna or floras independently of time since, as has

been shown above there is no sufficient reason to warrant their necessary con-

temporaneity. To consider space independing of time is against the principle

of relativity just as well as to consider time independent of space.

Of course no great accuracy has evei been asserted of the geological

contemporaneity. A geological period is understood to represent a long time

perhaps long enough to allow evolution and migration of certain groups of

organisms to have prodhced sufficiently distinct and universal types which

may be then taken as characteristic of the time. The importance of the speed

of evolution for the correlation value of the fossils is usually well understood

by paleontologists who base their age determination especially on the "index

fossils" which expression means those type fossil organisms which had a rapid

evolution and short life. However if index fossils of same species are found

at two distant regions, we have;to consider not only the time for evolution but

also the time for migration. The latter depends on various and variable con-

ditions such as marine or land communication, supply of food, changes ofclimate, oceanic currents, etc. of the bygone ages which are not always easily

determinable. Fossils of rapid evolution may happen to have had slow migra-

tion. Then index-fossils characteristic of a given in a given region would

indicate by no means the same time in another region. The speed of migra.

.ion therefore has a great importance in the question of geological contem-

poraneity, and we shall now enter into some closer discussion.

In the figure 1, some orgrnisms ate supposed to have migrated from

a to b while another branch went from a to c. Whatever was the route

followed, be it x, y or z, it is clear that organisms at b and c can not becontemporaneous to the original ones left at a (before tjo migrations reached

band e) although they may still be identical in species. Neither the firstorganisms of a some species at a and e are necessarily contemporaneous. 1f

the distance between these points are sufficiently great and communication not

H. T. Chang:Geologicat Co em.poraniy eiewed frbm Theory of Relativiti,1 48

very widely open the migration of organisms will most probably take time

TIME FIG. i too long to be neglected in

the geolegical chronology.

A second case

may. he discussed with the

figure 2. Certain of organ-

isms migrated from a to b

and e. The migration was

so complete that there was

no moro left of the given

type at a or those left at a

were soon completely ex-

tinguished or again com-

pletely migrated out. The

fossil distribution may be

then represented by theshadedareainfig.2. Such

DISTANCEfossils are then of veryrapid evolution and very

short live, satisfying, the necessary conditions of "index-fossils". But infact, fossils at a b and e are by no means contemporaneous each to other.

Their greater or less differ-

ence in age depends on the

distance and rate of migra-

tion wbile the speed ofevolution has here little

influence.

Let us now consi-, --

(1er a third case as shown - - - -

by fig. 8 Organisms of a

certain type migra td from

a to b and e while these of athe same type left at a con-

tinued to develop to a' and thence to a". Those arrived at b also continued

TIME

DISTANCE

C,

b'

44 Bulletin of th Geological Society of China

to develop to b'. Organisms at a" h' and o are contemporaneous, but

they are identical in type only if theTIME FIG.

organic evolution was exactly parallel

and uniform in all the different direc-

tions of. migration in such a way toproduce identical type at b and a',. and

at e, b' and a", notwithstanding thedifference.of distance to be covered by

the migration and he necessary

different environments of live at the

different points. The latter hypothesis

is evidently not acceptable.

If, however, exact contemporaneity is impossible to establish in

geology, is it. possible tp arrive at some approximate correspondence of geo-

logical time? Or to explain again by the figure 3, if we suppose the organic

evolution from a to b and e developed approximately in a similar way

although not exact the same as in the region a itself, the fogsils left at theseplaces may be perhaps comparable enough to suggest their correspondence in

age. Indeed, in this case, fossils. at b would be similar to those of a' horizon

at a, and those at e similar to those of a" horszon at a and b' horizon at h..

On the basis of this hypothesis. I have suggested in my paper in Chinese on

"Geology and relativity" a method of progressive correlation which is as

follows:

"Correlation of geological formations may be perhaps attempted at

in a progressive way proceeding step both chronologically and geographically,

still special ease must be taken not to take too shOrt time unit. Let us then

take geological period as time unit and divide the earth surface into small

areas of say one degree longitude and latitude each Take any one of these

areas as centre, and group all the areas around it in successive zones cadi

marked by a figure 1., 2, 3 etc. from centro outward. Then compare strata or

fossils of the most recent periods, say Quaternary, of the central area with the

corresponding strata or fossils of the first zone, and thence deduce the time

relation. ifl a similar way, we go on. progressively both in chronology and in

Q,

DISTANCE

FT. T. Chan q :Geooqieai Con(empora.neiti niewed from Theory of Relativity 45

geography; from Quaternary to Tertiary, Orot.aceous, Jurassic etc. in age and

from the first zone to the second, the third etc. in area. The differences of

characters of the successive periods and subjacent zones aro to be studied into

great minutia, and all correlations shall be based on exact facts. By carefully

proceeding in the way, it may be hoped to avoid serious errors" (12).

It now seems to .me that even such a method would still encounter

almost insurmountable difficulties. And this for the following reasons. (1)

Owing to the change of environmental conditions, organisms at a given region

may completely migrate out or be extinguished soon after the migration took

place. Thence difficulty of comparison between organisms in the two places.

(2) Organisms of rapid evolution often develop independently in one place

from another after the migration owing to the difference of environments. (3)

The continuous series of evolution of organisms with all the successive stages

of devolopment is seldom completely preserved in the geological formations.

(4) It is often impossible to find fossils along the whole route migration of a

given group of organisms. (5) The cradle where new species originated, or

in other words the central area from where a given species radiated and props..

gated to other parts of the world is usually uncertain and clifticnit todetermine.

No doubt the groat mass of paleontological and stratigraphical facts

fast accmnulated in all parts of the world will assist to gradually overcome

some of the above mentioned difficulties and thence perhaps to make one day

the approximate correlation possible. lin writing this paper, I have no inten-

tion to make useless and futile all the painstaking researches so far dono on

the geological correlation, nor to discourage further work in this direction

But scientific progress is only possible with frank discussion and there seems

to be no reason to hide the weak points of the chronlogical correlation methods

which are of so fundamental importance to our science.

(xz) Science (Chinese) Vol. X No. 9, 1925