V.V. Beloussov
Chairman Upper Mantle Committee
Moscow

DEAR PROFESSOR WILSON,

lt was very interesting to read your article Revolution in the Earth sciences [see page 10], which you kindly sent me. You succeeded in making a striking case for the necessity of a general theory in the geosciences. lt seems to me that our Upper Mantle Project is, in fact, intended either to work out such a theory, if possible, or, at least, to collect the necessary material.

You assert, however, that a theory already exists and that textbooks should he rewritten and education. reorganized in accordance with it. An important advantage of the new theory you see is a chance of its captivating young people and diverting a certain number of them from physics and mathematics.

I would Eke to say a few words on this subject,

1. You are surely mistaken when you say that nothing important has happened in geoscience since the time of Lyell. I cannot understand your passing over the contraction hypothesis. lt reigned in our science for almost a whole century and we owe to it great achievements in geology, especially in the second half of the last century.

I think that in geotectonics M. M. Tetyayev's ideas (1941) were also most revolutionary. He showed the regularity in relations between events previously regarded as disjointed, and established the principle of unity of geotectogenesis.

2. The example of the contraction hypothesis could serve as a warning to all those who are in a hurry to rewrite textbooks. At the end of the last century and even at the beginning of this one, few people questioned the correctness of the contraction hypothesis. And all textbooks were written on the basis of that theory. The fundamental principles of the contraction hypothesis became so much a second nature to geologists that up to the present they have been strongly reflected in the majority of ordinary regional geological papers.

And yet the foundations of the contraction hypothesis collapsed. The difficulties with a geological theory nowadays are due mainly to the fact that, though the foundations collapsed, the store of particular ideas and concepts still remains.

The contraction hypothesis was undermined not only because a new physical phenomenon was discovered--radioactivity--that turned upside down al¡ our ideas on the thermal regime of the Earth. It was undermined also because of its primitive nature; it schematized natural phenomena, reducing them to a state of complete distortion. It never could explain vertical (epeirogenetic) crustal movements. lt failed when detailed investigations established that folding can be of various types and of an obviously different origin (for instance, what relation is there between horizontal compression and platform quaquaversal folding, so interesting to the oil man?). Beginning in 1906 with Ampferer (after whom Fourmarier wrote so wonderfully about it in 1947) it has been shown repeatedly that the structure of a geosyncline, in all its complexity and history, cannot be explained by a rough mechanism of crushing between two rigid blocks. The list of cases in which the contraction hypothesis proved to be too schematic, could be much longer.

3. What is the situation now with the new theory that you are defending? There simply is no foundation to it: while, according to the then-accepted cosmogenic hypothesis of Laplace, it seemed most probable that the globe should grow cooler, nobody has shown that deep convection currents, which are necessary for your theory, really exist or even that they can exist. The computed schemes are even more primitive. For instance, they do not bother to take into consideration that the sources of heat are not outside the moving material, but in it. lt is not clear at all where and at what depth these currents are flowing. In the oceans they should be at the surface. Well, and under the continents, too?

It is not so difficult to compile a scheme of currents under the Atlantic Ocean only, but nobody has yet succeeded in constructing a scheme of currents for the entire globe, even a speculative one, that is mechanically possible. You have made such an attempt (Wilson 1965). Consider it attentively: Africa with its rift and the adjacent. Indian Ocean (also with a rift) present an insoluble problem. So, instead of drawing arrows that, according to the regularity that you consider to be fundamental, should point away from the rifts, you have drawn an arrow from the south northward under the entire African continent. Why? And why on the other side of the Indian mid-ocean ridge the arrows are also not normal to the rift, but parallel to it? And the northem part of the ridge. you have simply wiped it off the scheme. Why? Near the coasts of California you show currents that meet at right angles. Is this possible according to elementary principles of hydrodynamics?

As to the schematization of natural phenomena, the situation is not at all an improvement on the contraction hypothesis. For the development of a geosyncline you actually accept the same mechanism of horizontal crushing already discredited. Epeirogenetic movements continuously and universally taking place (compare thickness and facies of deposits) are left unexplained, They are not even mentioned. All the structural development is reduced to rifts and geosynclines, which are two structural poles associated with each other, First, there are not only geosynclines on the continents. My country, for instance, is mostly beyond young geosynclines, and we simply cannot forget the laws governing the development of extrageosynclinical areas. Second, geological data clearly indicate that rifts are very young: they originated much later than the beginning of the development of even the youngest (Alpine) geosynclines and, consequently, cannot he the cause of the origin of geosynclines. And what about the old geosynclines? The Hercynian, the Caledonian, the Precambrian? We have no data whatsoever about the existence of their corresponding rifts.

In the theory that you are so ardently advocating, the geological development of continents is much more schematized than was done in the contraction hypothesis. The geology of continents is simply and completely annihilated. Could it be that you really want to rewrite the textbooks, and throw overboard a great part of the outstanding achievements in the geology of continents?

This excessive schematization is caused by the fact that the oceans occupy first place in the new concept. Naturally, the successes in the study of oceanis are tremendous and they provided quite a new color to our ideas about the Earth. But no matter how great these successes, we should not forget that, owing to obvious circumstances, our knowledge of the ocean areas remains not only very schematic, but to a great extent indirect, being founded on interpretation of indirect data. Suffice it to say that we still do not know of what material the consolidated ocean crust consists. No one bus proved that it is serpentinic. On the other hand, we know a little about the crust of the continents.

In this way, the old, tested and rather precise geology of the continents is being sacrificed for the sake of as yet indefinite data on the structure of the oceans! You propose to use the process of repeated opening and closing of oceanic basins as the basis of historical geology. Would not it be better to wait until we get more direct evidence on the structure of the ocean floor? Would not such a theory have a reverse effect upon the young people to the one you expect, inasmuch as they are not going to be satisfied by an emotional effect, but will demand more exact justification?

4. Of course an advocate of any theory prefers data convenient for his purpose to the inconvenient ones. But when a person in doubt asks questions, they have to be answered. Otherwise an undesirable impression is created. I am enumerating here the questions that have been asked time and again, but for which no answers have been yet received:

(a) Since the spreading ocean floor predetermines that the crust in the ocean should be serpentinic, how can you explain such persistent thickness of the crust in the ocean and what is the Mohorovicic discontinuity in the ocean? (I think you will agree that the explanation suggested by Hess in 1962 is too artificial to he true.)

(b) What is the composition of the crust in such seas as the Sea of Okhotsk, Sea of Japan, the Caribbean Sea, the Black Sea? How was the crust formed there, as there are no rifts?

(c) If the currents involve the floor of the ocean up to

the surface, how are they able to descend under the continents without any deformation of the ocean floor even at the edges of the continents?

(d) If two opposing currents flow under the continent and meet each other, the latter will stop, apparently at the place where the effect of the two currents is counterbalanced. The young folded zone of the cordilleras and Andes is the edge of the continent. Why does the current from one side pass under the entire continent, while the current from the other side stops at the edge? What happens to the currents under Africa?

(e) In connection with the aforesaid a question arises as to the depth of the currents. What are the reasons for the slow vertical movements of anteclises and syneclises on platforms? Where are the chambers of magma that is ejected in geosynclines, on platforms and in the oceans? la the mantle? At what depth? And, if the continents are displaced in respect to the mantle, how does it happen that anteclises and syneclises remain in the same place as the continent for hundreds of millions of years and the magmatic centers are just as stable during the tectonic, cycles? How can a volcano that is displaced together with the floor of the ocean not lose its connection with its feeding chamber?

(f) What is the explanation for tectonic cycles with their regular and fundamentally uniform repetition of tectonic and magmatic phenomena? This question becomes especially acute because, according to the theory you are defending, at different times the continents were over different parts of the mantle.

(g) How can you explain the fact that the mean value of heat flows is the same on the continents as in the oceans?

(h) If a geosyncline originates at a descending current, that is, the coldest branch, how can you explain the signs of a substantial heating of the crust in the geosyncline (intrusions, regional metamorphism, granitization), confirmed by among other things measurements of old geothermal gradients by mineral geothermometers?

5. You believe that the way you indicate is the only one leading to generalization. The majority of Soviet geologists and geophysicists who study general problems of geology are of a different opinion. There is no doubt that there are also other ways. For instance, the ways I have tried to indicate in my papers. They seem to be more promising not only to me. Some people think that the old idea of the formation of continents by differentiation of the oceanic crust can still be revived. Your list of attempted generalizations published during recent decades would be much longer if you take into account the papers of Soviet researchers. From our point of view it is strange to pass over in silence the papers by A. D. Arkhangelsky (1941), V. A. Obruchev (1940), M. A. Ussov (1940), M. M. Tetyayev (1941), even without mentioning those still living. Our country occupies a sixth of the land on the globe and among its population there are geologists who feel their great responsibility to science and the economy of their country.

6. ft should be mentioned, of course, that modern. interpretation of geomagnetic observations favors the theory you. are defending. This is your strongest argument. But, strangely enough, it is the only one, because the others (Iike, for instance, the contours of the coasts, paleoclimatic data, and structural similarities) can always have another interpretation as well.

Naturally, geomagnetic data deserve close attention. But when they are placed against the enumerated impressive list of contradictions, a second thought is warranted on the significance of an extremely great scattering in the results of paleomagnetic data, on some very strange results obtained (indicating, for instance [Boer 1963], the movement of the Italian Alps from the Himalayas across Iran and Turkey, or the location of New Guinea, despite its primordial adherence to the circumpacific ring, during the Cretaceous in the middle of the Indian Ocean) and on those original assumptions on the constant structure of the magnetic, field of the Earth, on which the interpretation is founded. Bearing in mind such a number of contradictions in other geological and geophysical data, should not this only positive and ponderous argument in favor of your theory he subjected to especially scrupulous and objective analysis?

Are not, for instance, these very confident references to magnetic anomalies parallel to ocean rifts premature if we take into account that after more detailed investigations the stretches of anomalies fall apart into rather irregularly scattered patches (Matthews et al. 1965; Loncarevic et al. 1966)? When making toogeneral comparisons it is always easy to become a victim of illusions: certain groups of patches could appear to look like stretches. Remember the canals on Mars! And, by the way, why are there no such stretches near the Red Sea or near the grabens of East Africa?

Thus I am entirely for a general theory, but for a theory based on deep and precise study of all the aspects of phenomena, taking place both in the oceans and on continents, and which would unite all these events. I am afraid that, for the time being, we have studied natural phenomena much too insufficiently to formulate any well-founded theory. Still, we now have at our disposal new and effective technical and methodological means that should help us to fill in the main blanks within a reasonable time. To do this we should call upon our colleagues, the young ones especially. And it is our duty to indicate, on the basis of our experience, which routes are best to follow in studying the interior of the Earth and the processes that are taking place there.

Admittedly, to choose a route one needs working hypotheses. Better yet if there are several. From this point of view both the theory of continental drift and the concept of spreading ocean floor could serve as such working hypotheses along with others (Iike the concept on the differentiation of the ocean crust or an oceanization of the continental crust). A great number of hypotheses guarantees a varied approach, and that is only beneficial for our science.

But we will be bitterly reproached (perhaps also ridiculed!) by the coming generations if we call one of such working hypotheses a final theory, if we assert that the truth is at our elbow and that we only have to stretch out our hand to pick the flower. We have dedicated our lives to a difficult science, which, unfortunately, is still assembling fundamental data. We have only just begun to penetrate the secrets of the very shallow interior. It would be most irresponsible of us to tempt the young people, saying that all the difficulties are behind us and, instead of leading them along a hard and strenuous path of search and menial labor, inevitable for a scientist, to lull them with delusive hopes and dreams.

Respuesta de J.Tuzo Wilson...       

references

O. Ampferer, Uber das Bewegungsbildung von Faliengebirge, Austria, CeoL Reichsanst., Jahrb., Rd. 56, Wien (1906).

A. D. ArkhangeIsky, Geological structure and geological history of the USSR, Gosudarst. Ceo¡. lzd., Moscow (1941). Mussian)

J. de Boer, Geology oí the Vicentinian AIps (NE Italy), with special reference to their palcomagne~tic history, Geologica Ultra¡ectina, n. 11 (13).

P. Fourmarier, Les fomes en action dans la genese du refieí tectonique, Soc. Beige d'Etudes geog., Bulí., v. 17, n. 1 & 2, p. 20-57 (1947)

H. H, Hess, History oí ocean basins, in Petralogic seudies-a volume in honor oí A. F. Buddington, Geol. Soc. Am., New York (1962).

B. D. Loncarevic, C. S. Mason & D. H. Malthews, Mid-Aflantic ridge near 45* North, 1, The median valley, Canadian Jour. Earth Sciences, 3 (1966).

D. H. Matthews, F. 1. Vine, & 1. R. Cann, Geology oí an area oí the Carisberg ridge, Indian Ocean, CeoL Soc. Am., Bufl., v. 76, o. 6 (1965)

V. A. Obruchev, A pulsarion hypothesis in geotectonics, Akad. Nauk SSSR IzY., Ser. Ceo¡., n. 1 (1940). (Russian)

M. M. Tetyayev, The principles oí geotectonics, Gosudarst. Ceo¡. lzd., Moscow (1941). (Russian)

M. A. Ussov, A geotectonic hypolhesis oí seif-developmient in the matter oí the Earth, lzv. Akad. Nauk SSSR, Ser. Geol. Y. 1 (1940). (Russian)