THE IDEA OF CONTINENTAL DRIFT IN THE WORKS OF THE EARLY 19TH-CENTURY RUSSIAN SCHOLAR I. D. ERTOV

L. A. Pukhlyakov

(Presented by the Department of Fossil Fuels)

The idea of continental drift, before it became widely known, was expressed independently by various scholars. In Russia this idea was first formulated in 1811 by I. D. Ertov (1777–1828). It is known of this scholar that he was born into a merchant family and early developed a passion for reading books, but received no specialized education. Thus he is sometimes called self-taught. His enthusiasm for science led him to neglect his commercial affairs, go bankrupt, and subsequently work as a clerk for a wealthy merchant [2].

I. D. Ertov’s first book, An Outline of the Natural Laws of the Origin of the Universe [4], was published in 1798. A large part of it is devoted to setting forth the ideas, dominant in the second half of the eighteenth century, concerning the structure of matter, etc., including the theory of caloric, or phlogiston, which by the time this book appeared had already been refuted. However, alongside these ideas, it presents a new hypothesis of the origin of the planets and their satellites, which may be called an accretion hypothesis. According to this hypothesis, the matter of future planets and their satellites in the past existed in the Universe in a dispersed state, and then separate particles of this matter began to merge together and form large celestial bodies: suns, planets, comets [4].

This hypothesis corresponds to some extent to modern ideas about the development of the solar system. Thus, judging from the works of H. Alfvén [1], O. Yu. Schmidt [13], and others, the formation of the planets of the solar system may be reduced to the following. In the distant past the Sun intersected some gigantic cloud of dust-like matter. A significant number of such clouds is concentrated in the central plane of the Galaxy, and the Sun intersects this plane approximately every 100 million years. Simultaneously with the Sun, this cloud was intersected by some other star. Further, as noted in the works of the followers of O. Yu. Schmidt [8, 10], the two luminaries created gravitational depressions in each other’s gravitational fields.

Particles of the cloud of dust-like matter, finding themselves in the gravitational fields of large bodies, rushed toward them and would have passed by them, changing their direction in cosmic space, if there had been no gravitational depressions in these fields. But thanks to the gravitational depressions, these particles did not develop the velocities that would have been necessary to escape from the named gravitational fields. While consider-

the particles under consideration orbited around the Sun; the star that had passed near it moved considerably away, the gravitational depression it had created in the Sun’s gravitational field disappeared, and these particles found themselves captured by the Sun. Thus a protoplanetary cloud appeared in the vicinity of the Sun.

The particles of the protoplanetary cloud, as O. Yu. Schmidt [13] and his followers [8, 12] noted, collided with one another; in the process, the energy of their motion relative to one another was partly transformed into heat, and the heat was dissipated into outer space. The particles themselves, meanwhile, drew closer together, concentrating in groups according to energy levels relative to the Sun. The force of the particles’ impacts against one another gradually decreased and finally weakened to such a degree that after impacts the particles no longer flew apart, but stuck together.

The sticking together of particles led to the appearance of so-called protoplanets. Falling onto them, particles with low impact energy joined them and increased their mass [12].

With regard to the problem of the origin of planetary satellites, in 1973 [9] the following hypothesis was proposed, which was set forth in sufficient detail in 1976 [10].

New particles collided not only with protoplanets, but also with one another. At times such collisions occurred in the zones of influence of planets. And this led to the result that one of the colliding particles, and under certain circumstances both of them, became satellites of the planet [9]. It was in precisely this way, and only in this way, that the satellites Phobos and Deimos were captured by Mars. In the past, when the main mass of the protoplanetary cloud had not yet become part of the planets, collisions of particles of dispersed matter in the zones of influence of protoplanets were more frequent than at the present time; as a result, protosatellite clouds began to form there, from which the satellites of the planets subsequently formed. In 1975 E. L. Ruskol [11] proposed an analogous hypothesis for the origin of planetary satellites.

In I. D. Ertov’s first work [4] there is neither a theory of gravitational depression, nor even the problem of capture. The energetic aspect of the problem under consideration did not interest him at all. Possibly for this very reason he found no followers among the scientists of that time. But since, like I. D. Ertov, we deny the possibility that planets formed through separation from the Sun, and the possibility that satellites formed through separation from planets, we must regard him as our predecessor.

In 1811 I. D. Ertov’s second book, Thoughts on the Origin and Formation of Worlds [5], was published. More attention is devoted here to the question of the origin of the planets than in the first book. However, the essence remains the same. What is new here is only his supposition that in the initial period of their existence the planets did not possess rotation [5, p. 133]. According to I. D. Ertov, they acquired it later, supposedly under the influence of the Sun [5].

Both of these propositions are incorrect, for the planets formed from particles moving relative to one another, of which the outer particles (those more distant from the Sun) had a greater velocity. Hence the planets acquired so-called direct rotation, in which the particles of the planet more distant from the Sun overtake those facing the Sun.

However, even in these propositions of I. D. Ertov there is something new and rational. The fact is that even at the present time, when in-

instrumentally demonstrated irregular increases in the speed of the Earth’s rotation [7], many scholars believe that in the course of their development planets can only reduce the speed of their rotation. I. D. Ertov raises the question of the possibility of an increase in the speed of rotation of planets.

At present this view is in a state of flux. Some scholars still believe that, in the process of evolution, under the influence of tidal friction, the speed of rotation of planets can only decrease. Others [7, 8, 9] believe that in certain cases, when satellites begin to approach planets, or when heavy masses within planets are displaced toward their centers, planets increase the speeds of their rotation.

Further developing his thought, I. D. Ertov comes to the conclusion that, as a result of the Earth’s acquisition of rotation, there must have occurred a displacement of the Earth’s crust in a direction opposite to the direction of the Earth’s rotation [5]. I. D. Ertov saw proof of his hypothesis in the existence of oceans on the Earth, and above all of the Atlantic [5, pp. 134—141]. However, he does not yet speak of the parallelism of the shores of this ocean; evidently, at that time he had not paid attention to this property of the named ocean. We, contemporary mobilists, see his merit in this as well. For both before Ertov and many years after him, many tectonicists do not wish to pay attention to this fact. They are ready to speak about the parallelism of the shores of the Atlantic Ocean, ready to acknowledge this fact as interesting and explain it as accidental, but the very fact of the existence of oceans is of no interest to them. For them the oceans are eternal, unchanging, and require no explanation.

Here it is interesting to note that A. Wegener, whose book [3] is the foundation of the modern doctrine of continental drift, connected this phenomenon with tidal friction, that is, with the slowing of the Earth’s rotation. The modern point of view on this question comes down to the fact that continental drift was connected above all with an increase in the speed of the Earth’s rotation, caused by the approach to it of a second satellite [8, 9]. Thus, I. D. Ertov’s hypothesis on the problem of continental drift is closer to modern views than Wegener’s hypothesis.

In his last book, entitled Minor Writings, Replies to Criticism, and an Abridgment of Thoughts on the Origin and Formation of Worlds [6], I. D. Ertov, in proof of his hypothesis of the origin and development of the Earth, already refers to the parallelism of the shores of the Atlantic Ocean [6, pp. 176—184]. Here he also clearly formulates the proposition that, before the appearance of the oceans, the surface of the Earth was practically level, and the water envelope covered it with a layer of approximately uniform thickness, which also corresponds to modern views.

On the problem of the origin of mountains, I. D. Ertov expressed thoughts very close to those which A. Wegener expressed about a hundred years later and which amounted to the view that the formation of mountains occurred as a result of the pressure of the Earth’s crust, moving westward, upon its immobile areas in the process of the formation of the Atlantic Ocean [6].

Contemporary mobilists approach this problem differently. In their opinion, the main phases of expansion of the Atlantic and Indian Oceans correspond to epochs of increase in the speed of the Earth’s rotation, while the main phases of mountain formation correspond to epochs of decrease in the speed of the Earth’s rotation. The Pacific Ocean, in their opinion, formed as a result of the covering of an enormous territory by a thick layer of fragments joined—

which approached the Earth as a second satellite [8, 9]. There are other points of view on this question as well, but here the views of present-day mobilists are set forth—that is, of the representatives of the trend to which I. D. Ertov belonged in his time.

In conclusion, it should be said that I. D. Ertov consistently defended and propagated the new hypothesis of the development of the world that he had worked out in his youth, which may be called accretionary. This hypothesis runs like a red thread through all his scientific works, being supplemented and refined over time. However, in the scientific works of authors of that period we encounter neither approval of his ideas nor objections to them. His contemporaries did not notice him; nevertheless, after one hundred and fifty years, scholars arrived at analogous conclusions and, on the basis of these conclusions, created a new cosmogony and a new geotectonics.

REFERENCES

1. Alfvén, H. Atom, Man, Universe. Trans. from English. Moscow, Znanie, 1973.

2. Belostotskii, I. I. “A Russian Mobilist of the Early Nineteenth Century.” Priroda, 1972, No. 6.

3. Wegener, A. The Origin of Continents and Oceans. Trans. from German. Berlin, Vostok, 1923.

4. Ertov, I. D. An Outline of the Natural Laws of the Origin of the Universe, vol. 1. St. Petersburg, 1798.

5. Ertov, I. D. Thoughts on the Origin and Formation of Worlds. St. Petersburg, 1811.

6. Ertov, I. D. Minor Writings, Replies to Criticism, and an Abridgment of Thoughts on the Origin and Formation of Worlds. St. Petersburg, 1829.

7. Pariiskii, N. N. “The Nonuniformity of the Earth’s Rotation.” Transactions of the Geophysical Institute, No. 26 (153), Moscow, 1957.

8. Pukhliakov, L. A. A Survey of Geotectonic Hypotheses. Tomsk, Tomsk State University Press, 1970.

9. Pukhliakov, L. A. “Some Remarks on the Problem of Continental Drift.” Geology—Proceedings of the Conference Dedicated to the 75th Anniversary of the Institute. Tomsk, Tomsk State University Press, 1973.

10. Pukhliakov, L. A. “The Earth’s Past from the Standpoint of the Hypothesis of the Accretion to the Earth of a Second Satellite.” Proceedings of the Tomsk Polytechnic Institute, vol. 288, 1976.

11. Ruskoll, E. L. The Origin of the Moon. Moscow, Nauka, 1975.

12. Safronov, V. S. Evolution of the Protoplanetary Cloud and the Formation of the Earth and Planets. Moscow, Nauka, 1969.

13. Schmidt, O. Yu. Four Lectures on the Theory of the Origin of the Earth. Moscow, Publishing House of the Academy of Sciences of the USSR, 1949.