On Some Attempts to Refute the Continental Drift Hypothesis

L. A. Pukhlyakov

(Presented by Professor D. S. Mikov)

As proof of the hypothesis of continental drift, initially only the parallelism of the opposite shores of the Atlantic Ocean and the similarity of their geological structure were cited. However, opponents of this hypothesis characterized this parallelism as pure chance and asserted that new data would definitively refute the idea of continental drift. In the 1950s such data appeared. These were paleomagnetic data. Yet they not only did not refute the idea of continental drift but, on the contrary, confirmed it.

It is interesting to note that these studies were undertaken to verify the opinion of paleoclimatologists concerning the displacement, in the past, of the poles of our planet. This opinion was brilliantly confirmed. But the surprising thing is that the positions of the north pole obtained from rocks of North America almost every time lay west of its positions obtained from rocks of the same age taken in Europe and Asia. This could be explained only by assuming that, after their formation, the rocks of North America had been displaced westward relative to the rocks of Europe and Asia.

Paleomagnetic data not only confirmed the idea of continental drift in general form, but also clarified certain aspects of this question. Thus, to explain drift, many representatives of this field of science—for example A. Wegener [2], I. V. Kirillov [3], and others—proposed hypotheses from which it followed that continental drift should be continuing at the present time. But others, whose ideas were based on the hypothesis of an increase followed by a decrease in the speed of the Earth’s rotation, asserted that this process should have ceased sometime around the end of the Mesozoic [7, 8, 10]. The averaged positions of the projections of the north pole from Cretaceous rocks of North America and Eurasia, obtained from the data of A. Cox and R. Doell [4], practically coincide [11, fig. 9]. It follows from this that the drift of North America relative to Eurasia ceased at the end of the Late Cretaceous. In an analogous way it was shown that the movement of India northward ceased in the Post-Miocene. Paleomagnetic data confirmed the supposition of a counterclockwise rotation

arrow by 45–50° for the Iberian Peninsula [9], and much else. Thus, paleomagnetic data proved to be exceptionally valuable for resolving a large number of questions concerning the past of our planet.

However, the opponents of the continental-drift hypothesis were not convinced by the data of paleomagnetism. In the opinion of some of them, for example I. A. Rezanov [12], the discrepancy between the projections of the poles discussed above can be explained by the fact that in the past our planet had several magnetic fields, and one of these fields supposedly magnetized the rocks of America, while others magnetized the rocks of Europe, India, and other blocks of land.

Here it must first of all be noted that the magnetic fields of planets arise owing to their rotation [1, p. 456], more precisely owing to the rotation about their axes of electric charges located in their atmospheres and, in part, at some depth beneath the solid surface [11]. The motion of these charges is entirely similar to the motion of an electric current in a solenoid and, consequently, must be accompanied by the appearance of a magnetic field.

Under the influence of particles accompanying solar radiation and of various cosmic processes, charges of one sign or the other predominate in planetary atmospheres. Accordingly, planets acquire magnetic fields now of one direction, now of another.

As for the discrepancy between the magnetic axis of our planet and its axis of rotation, this fact can be explained by the circumstance that over oceans, continents, and mountain structures there exist different conditions for the accumulation and preservation of electric charges. As a result, in some places they prove to be larger, in others smaller. And since the named forms of relief are distributed unevenly over the Earth’s surface, the electric charges likewise prove to be distributed unevenly over it; hence the magnetic field generated by them in the course of the Earth’s rotation has an axis that does not coincide with the Earth’s axis of rotation.

As is known, the magnitudes of electric charges in the Earth’s atmosphere are influenced by solar activity, by seasonal temperature fluctuations, and even by diurnal changes in the state of the atmosphere. Corresponding to this are changes in the intensity and direction of the Earth’s magnetic field.

The hypothesis set forth explains well the fact that celestial bodies having no atmospheres, or having insignificant atmospheres—for example, the Moon or Mars—practically have no magnetic fields. In analogous fashion, planets possessing atmospheres of considerable thickness but rotating comparatively slowly—for example, Venus—also have very weak magnetic fields. V. I. Pochtarev is wrong in this respect; proceeding from the assumption that the magnetic fields of planets are supposedly connected with certain processes occurring in the internal parts of planets, he asserts that the intensity of the magnetic field of Venus is almost equal to the intensity of the Earth’s magnetic field [6, pp. 129, 133–143]. According to data obtained with the aid of the interplanetary station Venera-4, the magnetic moment of Venus is at least three thousand times smaller than the magnetic moment of the Earth [5]. Similar data were obtained with the aid of the interplanetary station Mariner-2 [1, p. 456].

Proceeding from the concept set forth concerning the origin of planetary magnetic fields, the Earth in the past could have had only a single-axis, or, as it is customarily called, dipole magnetic field—that is, a field having only one magnetic axis. But even if it had had as many as two magnetic axes, then in the absence of continental drift the projection of the north-

of the north pole, according to data from American rocks, would coincide with the projection of this pole according to data from European rocks. Let us consider, for example, the Earth’s magnetic field of Carboniferous time, for which, according to data from American rocks, the north pole was located on the eastern coast of Korea, while according to data from European rocks it was approximately a thousand kilometers east of Japan [11, Fig. 6], so that the distance between the projections of this pole proves to be close to 2000 km.

If the matter here concerned rocks sampled near the projections of the poles, one might agree that in one case the influence of the north pole of one magnetic field predominated, and in the other—the influence of another. But the point is that the rocks of North America were affected only by a magnetic field with its north pole in the region of the eastern coast of Korea, whereas the rocks of Europe were affected by a magnetic field with its north pole situated east of Japan. One cannot possibly agree with such an assumption.

In fact, how, at such a distance from nearly adjacent axes, could one magnetic field have excluded the influence of the other? After all, if we place two artificial magnets in such a way that their axes form an angle of 18° (the magnitude of the angle between the straight lines passing through the center of the Earth and the above-mentioned projections of the north pole), and if, on a line forming an angle of 70–80° with them, we place a magnetic needle, then we shall detect a single magnetic field. An analogous picture would also have been observed in the case we assume of a two-axial magnetic field of the Earth in Carboniferous time; namely: upon the rocks of America and Europe a two-axial magnetic field with poles in Korea and east of Japan would have acted as a single-axis magnetic field, and in studying the magnetic properties of these rocks we would have come to the conclusion that the magnetic field of our planet was single and that its north pole was located somewhere in the region of Japan.

Thus, the assumption of a two-axial magnetic field of our planet cannot explain the appearance of two or more projections of the north magnetic pole. Such facts can be explained only by continental drift or by rotations of individual parts of them relative to one another.

LITERATURE

1. J. Brandt, P. Hodge. Astrophysics of the Solar System (trans. from English). Mir Publishing House, 1967.

2. A. Wegener. The Origin of Continents and Oceans (trans. from German). Vostok Publishing House, Berlin, 1923.

3. I. V. Kirillov. The hypothesis of the development of the Earth, its continents and oceanic depressions. Bulletin of the Moscow Society of Naturalists, Geology Section, Vol. XXXIII, No. 2, 1958.

4. A. Cox and R. Doell. Survey of the phenomena of paleomagnetism (trans. from English). In: Problems of the Displacement of Continents. IL, 1963.

5. A. A. Lukin. The magnetic field around Venus. Priroda, No. 7, 1969.

6. V. I. Pochtarev. Magnetism of the Earth and of Cosmic Space. Nauka Publishing House, 1966.

7. L. A. Pukhlyakov. On the question of the origin of mountains and oceans (the hypothesis of an increase in the speed of the Earth’s rotation). Izv. TPI, Vol. 120, 1961.

8. L. A. Pukhlyakov. On the question of the origin of the Pacific Ocean. Izv. TPI, Vol. 127, No. 2, 1965.

9. L. A. Pukhlyakov. Did a westward drift of the Pyrenean Peninsula take place? Izv. AN SSSR, Geological Series, No. 8, 1966.

10. L. A. Pukhlyakov. A new hypothesis of the origin of mountains and oceans. Interuniversity scientific conference. Materials of the geographical section. West Siberian Book Publishing House, Omsk, 1967.

11. L. A. Pukhlyakov. A Survey of Geotectonic Hypotheses. Tomsk University Publishing House, 1970.

12. I. A. Rezanov. On continental drift (according to paleomagnetic data). Soviet Geology, No. 4, 1961.