Die Entstehung der Kontinente.

Gotha: Justus Perthes, 1912.

First edition, journal issues in the original printed wrappers. “Wegener is remembered today as the originator and one of the chief proponents of the theory of continental drift, which he conceived after being struck by the apparent correspondence in the shapes of the coastlines on the west and east sides of the Atlantic, and supported with extensive research on the geological and paleontological correspondences between the two sides. He postulated that 200 million years ago there existed a supercontinent (‘Pangaea’), which began to break up during the Mesozoic era due to the cumulative effects of the ‘Eötvös force,’ which drives continents towards the equator, and the tidal attraction of the sun and moon, which drags the earth’s crust westward with respect to its interior. Wegener’s drift mechanism was later shown to be untenable; it has been replaced by the idea of convection currents in the earth’s upper mantle. Wegener’s first publication on continental drift appeared in three issues of Petermanns Mitteilung in April-June 1912; however, Wegener’s theory attracted little interest until 1919, when he published the second edition of his treatise Die Entstehung der Kontinente und Ozeane. Between 1919 and 1928 continental drift was “the focus of much controversy and debate, but the theory afterwards fell into obscurity, not to be revived until the discovery of new paleomagnetic evidence in the 1950s” (Norman). Wegener (1880-1930) died at the early age of 50 on an arctic expedition at Eismitte in Greenland. ABPC/RBH record no copies of this important paper in the original printed wrappers since the Norman copy, which was rebacked (Christie’s, 29 October 1998, lot 1337, $2185).

Before Wegener put forward his revolutionary theory, it “was widely believed that continents and ocean basins are primordial features. This conviction was reinforced by global oceanographic surveys in 1872-77 demonstrating the Earth’s bimodal elevation frequency, and simultaneously by gravimetric and geodetic surveys in the western U.S. and elsewhere that confirmed the principle of isostasy (i.e. an elastic crust that floats on a fluid medium). A continent can neither rise from the abyss or sink to abyssal depth spontaneously. The mass excess of its elevation is compensated by a mass deficit at depth. If it were to move sideways, it would have to drag its moorings along with it, which was thought to be absurd. Isostasy cut both ways however: it rendered physically implausible the land ‘bridges’ invoked by geologists to account for ancient floral and faunal similarities between continents now far apart” (Hoffmann, ‘The tooth of time: Alfred Wegener,’ Geoscience Canada 39 (2012), 102-111).

Wegener’s interest in the problem was awakened by two chance observations. “Wegener’s office mate had received a world atlas with up-to-date bathymetric maps for Christmas in 1910. They noticed that the east coast of South America appears to fit against the west coast of Africa, “as if they had once been joined”. The fit is even better, Wegener continued, if the tops of the respective continental slopes are matched instead of the present coastlines. “This is an idea I’ll have to pursue”, but he did nothing more with it until the Fall of 1911, when he “quite accidentally” came upon a treatise on continental paleogeography (strata, flora, fauna and climate), compiled by a German high-school teacher only two years older than himself. Here, Wegener learned of the remarkable similarities in Mesozoic flora and fauna between Brazil and Gabon, and also of the concept of sunken ‘land bridges’ then widely invoked by geologists to account for such linkages. As a geophysicist interested in glaciology, he

was more convinced than contemporary geologists that isostasy precludes land bridges from sinking to abyssal depth. When Wladimir Köppen gently advised him not to stray too far from what he knew, Wegener wrote back (in early December) that the geological linkages require either land bridges or continental displacements, but “a continent cannot sink, for it is lighter than that upon which it is floating. Therefore, let us, just for once, take [displacement] into consideration! If such a series of astonishing

simplifications follow, and if it is shown that ‘rhyme and reason’ will now come to Earth history, why should we hesitate to cast the old view overboard?”” (Hoffmann).

On 6 January 1912 Wegener “presented a startling new vision of crustal history at a meeting of the recently founded Geological Association (Geologische Vereinigung) in Frankfurt. The talk did not bring pleasure to its listeners. Not yet 32, Alfred Wegener had already published in several branches of meteorology and his admired textbook, Thermodynamics of the Atmosphere (1911) showed him to be unusually skilled at synthesis. But he was unknown in geology and had only been seriously reading the geological literature for about four months. Nevertheless, so many published facts seemed inexplicable if his theory was wrong, that he submitted the text of his talk to the Geological Association under the brash title, The Origin of Continents [Die Entstehung der Kontinente]. He proposed that geological interpretations would be greatly simplified if continents were allowed to undergo large relative horizontal displacements. The continents of today are the fragments of an ancestral landmass that rifted apart progressively in Mesozoic and Cenozoic time, allowing the Atlantic and Indian Ocean basins to grow at the expense of the Pacific. Not satisfied, he wrote an expanded version under the same title that was published in a leading geographical journal in three installments [the offered paper]. From the start, geographers were as engaged as geologists in the controversy over continental drift. But with war clouds looming over Europe and RMS Titanic hogging the headlines, it would be ten years and three editions of his subsequent book, The Origin of Continents and Oceans [Die Entstehung der Kontinente und Ozeane, 1915], before Wegener-bashing began in earnest.

“The longer 1912 paper came out in three installments: (1) geophysical arguments, (2) geological arguments, and (3) remaining geological arguments, present displacements and polar wobble. In (1) he introduces the elevation duality, gravity measurements and isostasy, thickness of the continental rafts, their composition, their plasticity in relation to that of their substrate, volcanism, and possible causes of displacement. Wegener did not distinguish between oceanic crust and mantle: the composition of the mantle was then unknown. He used [Eduard] Suess’s terms, ‘sial’ for the continental rafts and ‘sima’ for the substrate, assumed to be directly covered by abyssal sediments. He uses the term ‘crust’ as synonymous with ‘lithosphere’. He

expends little space on causes, which he considers to be premature. “It will be

necessary first to exactly determine the reality and the nature of the displacements before we can hope to discover their causes …

“The geological arguments are the strongest part of the paper and surprise even today. He reviews the evidence for active rifting in the Rhinegraben and the Red Sea – East African rift system. He compares the structure and geological history of his Atlantic conjugate margins, estimating the age of opening of different segments and speculating on connections between South Atlantic opening and Andean

contraction. His estimates are everywhere too young—Paleogene (actually Early Cretaceous) in the South Atlantic, Neogene (actually Jurassic) in the North Atlantic and Quaternary (actually Eocene) between NW Europe and Greenland. The last estimate in particular led him to predict that the separation rate between NW Europe

and Greenland is ~2 meters per year and testable by geodetic experiment. His separation age being at least 100 times too young, the rate is too fast by the same multiple. In the next section, on Gondwanaland, his estimated separation ages for Africa–Madagascar, Australia–Antarctica, and Australia–India are broadly correct. Why did he insist that no ocean existed to the northwest of Europe in the Pleistocene? It is because ‘steppe animals’ (mammoth, woolly rhino, etc.) existed in Central Europe during Pleistocene interglacial times, but not during the Holocene. He infers a climate like southern Russia and western Siberia for Central Europe, which would be “implausible with the present ocean so close in the west”. It remains a sound argument, but for the human ‘overkill’ hypothesis. Next he turns to the ‘Permian’ glaciation, represented by “indisputable ground moraines” on “typically striated pavements” in Australia, South Africa, eastern India and South America. With continents in fixed positions, Permian ice sheets occurred across most of the southern hemisphere, while in the northern hemisphere no verified Permian glacial deposit exists anywhere. This represents “a hopeless riddle for paleogeography.” In Wegener’s continental reconstruction, the various ice sheets are brought together into an area no larger than that occupied by the Pleistocene ice sheets. He infers that this area was centered over the south pole, which would then have been located near the southern tip of Africa. The north pole would lie in the north Pacific Ocean, taking “everything mysterious away from the phenomenon.” The paper reaches its climax when Wegener contrasts the Atlantic–Indian and Pacific ocean basins, explicitly as described in the opening stanzas of [Suess’s] Das Antlitz der Erde (1904). The Atlantic margins, with their “ragged shorelines and cut tablelands”, follow the inner sides of older mountain belts (Appalachians, Caledonides, Mauritanides, Cape Foldbelt). The same is true for the Indian Ocean, except west of the Indus River and east of the Bay of Bengal, where the active Eurasian mountain front “spills into the ocean” in the Makran and the greater Sunda arc. In the Pacific, smooth arcuate coastlines or volcanic chains parallel fold belts that are everywhere vergent toward the ocean. “No fold belt borders the Pacific from its inner side; no platform projects into the ocean.” He notes that the Pacific is on the whole deeper than the Atlantic, with correspondingly less calcareous abyssal sediments, and that Pacific volcanic rocks are less chemically evolved. These differences follow automatically from the hypothesis: “While the Atlantic opens, nearly all the Pacific margins approach towards its center; along its coasts widespread compression and convergence occur, but tension and rifting in the Atlantic”. Foreshadowing the Wilson cycle he writes, “the rift that once opened to form the Pacific and to compress the primeval continent [Pangaea] from both sides, originated in oldest geological times, and the resulting motion was long extinct when the forces (that formed the Atlantic) commenced.” Returning to the Atlantic, he suggests an explanation for seafloor topography. Since large areas of the seafloor are isostatically compensated, areas that are younger and hotter will be modestly elevated over those that are older and colder. “The depth variation appears also to suggest that the Mid-Atlantic Ridge should be regarded as the zone in which the floor of the Atlantic, as it keeps spreading, is continuously tearing open and making space for fresh, relatively fluid and hot sima from depth.” This is not seafloor spreading as we now know it—no oceanic crust is formed by partial melting of mantle peridotite. Rather, he visualizes the sima as being exhumed in a solid state, as it does in the transition to seafloor spreading on non-volcanic margins. It is close enough to seafloor spreading, however, that one is left to wonder why Wegener subsequently abandoned such a promising lead. Had he not been deceived into thinking that the sima would readily accommodate the drift of tabular crustal bergs, would he not have tried moving the sima along with the sial? After all, he was not driven by any particular geodynamic mechanism (he admitted he had none), he was driven by the converging lines of geological evidence.

“Wegener concludes the geological arguments with paleoclimatic (mainly floral) evidence for polar wander (i.e. true polar wander), which he assumes is as important as continental drift in accounting for observed changes in paleolatitude since the Permian glaciation. Moreover, he suggests that continental displacements were the

cause of polar shifts, because “the pole of rotation must follow the pole of inertia”. He considers it premature, however, to interpret the ‘Lower Cambrian’ glaciations in Norway, China and Australia (read Cryogenian snowball Earth) in terms of polar wander. Wise man! The final and shortest section of the paper concerns geodetic proofs (i.e. tests) of active continental displacement. He describes astronomical determinations of longitude by successive expeditions to particular sites in Greenland, and longitude differences between Europe and North America from Trans-Atlantic cables. Wegener came in for heavy criticism from geographers for suggesting that such data were consistent with displacement. A more charitable view is that Wegener was providing ‘proof of concept’ and a baseline for “astronomical positioning during the course of several decades.” Wegener concludes with a comment on polar wobble, discovered by the American astronomer Seth Chandler in 1891 and monitored since 1899 by the International Latitude Service. He suggests that a shift in the inertial axis would cause the centre of the perturbation curve to migrate as well. He speculates that continental displacements might be the cause of the wobble itself. “This is because a perturbation once present must come to rest in spirals so that the pole of rotation and that of inertia will coincide as a consequence of the work it does in the Earth’s viscous interior. If the pole of inertia shifts, the pole of rotation moves out at a right angle and follows the perturbation curve, first with a large radius, then with a smaller and smaller one until it reaches the new pole of inertia” (Hoffmann).

“The period between 1920 and 1924 marked Wegener’s deepest involvement with the theory of continental displacements. A third edition of his book on the subject appeared in 1922 and was translated into English, French, Russian, Italian, Spanish, and Japanese. The theory was widely discussed and seems to have been favored more by geographers and paleoclimatologists than by geologists and geophysicists. It appealed to geologists whose fieldwork took place in the southern hemisphere much more than to those who worked in the northern hemisphere” (DSB).

“The delayed reaction to Wegener and Köppen’s theory by geologists, geographers and geophysicists took place between 1922 and 1928. Discussion meetings were held in England, South Africa and New York. Reviews of The Origin of Continents and Oceans appeared in leading international journals, starting with a highly favourable one in Nature of the 2nd edition. It concludes, “The revolution in thought, if the theory is substantiated, may be expected to resemble the change in astronomical ideas at the time of Copernicus. It is to be hoped that an English edition will soon appear.” Others were less kind. The reaction to Wegener has been a focus of attention by historians (including geologists), seeking reasons for the fury of Wegener’s critics” (Hoffmann).

“However, almost half a century later, with the advent of new methods and knowledge (sea floor spreading) and the discovery of paleomagnetism (1950), this concept was fully revived and fully accepted, upgraded and improved. The model of the motion of large planetary plates (continental and oceanic) gave birth to the theory of plate tectonics. Acceptance of this theory over the last 50 years has radically changed scientific knowledge about the mechanisms and types of movements that have led to global changes on the Earth (climate change, melting glaciers, creating a system of mountain, ocean circulation, earthquakes, volcanoes and other geological phenomena)” (Rundić, ‘Centenary anniversary of the theory of continental drift by Alfred Wegener and its significance for geosciences and human society,’ Bulletin of the Natural History Museum 5 (2012), 21-33).

Wegener’s lecture to the Geologische Vereinigung was printed in Geologische Rundschau, Bd. 3, n. 4, 9 July 1912, pp. 276-292. Although composed first, it was thus published later than the present greatly expanded work, which appeared in April-June of the same year.

Norman 2192. Marvin, Continental drift: The evolution of a concept. Washington DC: Smithsonian Institution Press, 1982 (see pp. 66-95).

Pp. 185-195, 253-256, 305-309 and one folding plate (no. 36) in three complete issues of Dr. A. Petermanns Mitteilungen aus Justus Perthes' geographischer Anstalt, Bd. 58, April, May & June 1912. 4to (277 x 230 mm), pp. [185]-248 with 8 plates (5 folding); [249]-304 with 7 folding plates; [iii], iv-xvi, [305]-314 with 6 plates (3 folding), many of the plates being coloured. Original printed wrappers, old tape repairs to hinges, extremeties slightly frayed. Rare in wrappers. Custom cloth box.

Item #4417

Price: $5,500.00

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