Wegener Hypothesis Research Articles

Centres of Development and Patterns of Distribution of the Family Melastomataceae in Indo-Malesia

1.The Melastomataceae is a homogeneous family of about 220 genera and 5300 species and is generally confined to the tropical and subtropical regions, avoiding arid conditions and attaining prolific developments in the rain forests between the tropic of cancer and the tropic of capricorn. More than one half of the World's melastomataceous genera (about 120) and two-thirds of the total number of species (about 3353) are confined to the New World. The melastomataceous flora of Indo-Malesia consists of 64 genera and about 1300 species. In the Old World the incidence of melastomataceous species for Indo-Malesia and Africa is in the ratio of 2:1.2.The present distribution of Melastomataceae in both the New World and the Old World is discussed on the basis of Wegener's hypothesis of "Continental Drift". Instead of considering the island of Madagascar as the centre of origin of the family in a restricted way, it is considered that "Gondwanaland" was ideally suited for the melastomataceous flora and those blocks that moved away after the breaking up of this huge continental mass in the Late Cretaceous, each carried their own share of melastomataceous species which, after gradual establishment in new situations during a long span of time and space, proliferated into several new taxa by an intensive process of evolution.3.The Deccan Peninsula + Ceylon block in drifting over the Indian Ocean must have carried the original Gondwanaland stock and gene-pool of the Melastomataceae which later-when this block was fused with Laurasia and the Tethys Sea had disappeared-became the centre of development of the family in continental Asia. Then Melastomataceae could further develop on the southern part of Laurasia and from there migrate eastward to the Malesian islands, the Western Pacific and northern Australia.This implies the conclusion that, though Australia also formed part of the ancient Gondwanaland, this cannot have carried part of the ancient Gondwanaland Melastomataceae when Australia drifted apart.4.An attempt has been made to assess the centres of distribution of Indo-Malesian Melastomataceae and from this study the following four centres of development are proposed : (i) The Deccan-Ceylon centre, (ii) The Himalayan-Yunnan centre, (iii) The Sunda centre and (iv) The Philippine-Papuan centre.5.The Island of Borneo is unique in having the largest number of genera-42 out of the Indo-Malesian total of 64 genera-and the largest number of species i.e. 257. Perhaps, it is due to the part played by the mountain of Kinabalu in enriching the floristic composition of Borneo. It is generally considered by phytogeographers that Kinabalu is a great sanctuary of flora, past and present, and a nursery of endemic elements.

FROM THE CONTRACTING EARTH TO CONTINENTAL DRIFT: WEGENER'S INFLUENCE ON PORTUGUESE AND SPANISH SCIENCE TEXTBOOKS THROUGH THE TWENTIETH CENTURY

ABSTRACT Alfred Wegener's work on continental drift profoundly influenced the development of geology during the twentieth century. The main objective of this historical research is to explore how Wegener's hypothesis about the origin of continents and oceans influenced Portuguese and Spanish science textbooks published in the twentieth century. For this purpose, a qualitative method based on the Chevallard's concept of didactic transposition was used. The didactic transposition of the fundamentals of continental drift, including displacements forces and geographical, geophysical, geological, paleontological, biological, and paleoclimatic arguments used by Wegener to support this hypothesis, was studied in a comprehensive sample of twenty science textbooks published after the publication of Die Entstehung der Kontinente und Ozeane (Wegener 1915). The analysis of textbooks shows that the didactic transposition of continental drift was commonly present in Portuguese and Spanish textbooks beginning in the 1930s, although, with different degrees of development. Science textbooks since the 1950s presented the displacement forces of sial continental blocks proposed by Wegener, namely the centrifugal force of Earth's rotation and the attractive gravitational force that results from the interaction of the earth with the moon and sun. The geographical, geological, paleontological and biological arguments supporting continental drift were commonly addressed in many science textbooks, followed by the paleoclimatic arguments. The geophysical arguments were briefly addressed in only two textbooks. Many Portuguese and Spanish textbooks also presented critiques of Wegener's work, mainly focused on the lack of explanation for the origin and nature of forces that could move continents at the Earth's surface.

Ophiolites in ocean–continent transitions: From the Steinmann Trinity to sea-floor spreading

Before the theory of plate tectonics took hold, there was no coherent model for ocean–continent transitions that included both extant continental margins and fragmentary ancient examples preserved in orogenic belts. Indeed, during the early 1900, two strands of thought developed, one relying on the antiquity and permanence of continents and oceans, advocated by the mainstream of the scientific community and one following mobilist concepts derived from Wegener's hypothesis (1915) of continental drift. As an illustration of the prevailing North-American view, the different composition and thickness of continental and oceanic crust and the resulting isostatic response showed “how improbable it would be to suppose that a continent could founder or go to oceanic depth or that ocean floor at ± 3000 fathoms could ever have been a stable land area since the birth of the oceans” [H.H. Hess, Trans. R. Soc. London, A 222 (1954) 341–348]. Because of the perceived permanence of oceans and continents, mountain chains were thought to originate from narrow, elongated, unstable belts, the geosynclines, circling the continents or following “zones of crustal weakness” within them, from which geanticlines and finally mountain belts would develop. This teleological concept, whereby a geosyncline would inevitably evolve into a mountain chain, dominated geological interpretations of orogenic belts for several decades in the mid-twentieth century. However, the concept of permanence of oceans and continents and the concept of the geosyncline had already met with the critiques of Suess and others. As early as 1905, Steinmann considered the association of peridotite, “diabase” (basalt/dolerite) and radiolarite (a typical ocean–continent transition assemblage), present in the Alps and Apennines, as characteristic of the deep-ocean floor and Bailey (1936) placed Steinmann's interpretation into the context of continental drift and orogeny. Indeed, in both authors’ writings, the concept of ophiolites as ocean crust is apparent. Between 1920 and 1930, the stage was thus potentially set for modern mobilist concepts that were, however, to prove attractive to only a small circle of Alpine and peri-Gondwanian geologists. After the Second World War, the 1950s saw the rapid progress of the geophysical and geological exploration of oceans and continental margins that provided the data for a reevaluation of the geosynclinal concept. Actualistic models now equated the former preorogenic miogeosyncline of Stille (1940) and Kay (1951) with passive continental margins [C.L. Drake, M. Ewing, G.H. Sutton, Continental margin and geosynclines: the east coast of North America, north of Cape Hatteras, in: L. Ahrens, et al. (Eds.), Physics and Chemistry of the Earth 3, Pergamon Press, London, 1959, pp. 110–189], the (American version of the) eugeosyncline and its igneous rocks with “collapsing continental rises” [R.S. Dietz, J. Geol. 71 (1963) 314–333] and the ophiolites, the Steinmann Trinity, of the (European) eugeosyncline with fragments of oceanic lithosphere [H.H. Hess, History of ocean basins, in: Petrologic Studies: a Volume to Honor A.F. Buddington, Geol. Soc. Am., New York. 1962, pp. 599–620]. The concept of sea-floor spreading [H.H. Hess, History of ocean basins, in: Petrologic Studies: a Volume to Honor A.F. Buddington, Geol. Soc. Am., New York. 1962, pp. 599–620; H.H. Hess, Mid-oceanic ridges and tectonics of the sea-floor, in: W.F. Whittard, R. Bradshaw (Eds), Submarine Geology and Geophysics, Colston Papers 17, Butterworths, London, 1965, pp. 317–333] finally eliminated the weaknesses in Wegener's hypothesis and, with the coming of the “annus mirabilis” of 1968, the concept of the geosyncline could be laid to rest. Ocean–continent transitions of modern oceans, as revealed by seismology and deep-sea drilling, could now be compared with the remnants of their ancient counterparts preserved in the Alps and elsewhere.

The British Reception of Alfred Wegener's Continental Drift Hypothesis

Wegener's hypothesis was introduced to Britain in 1922. First heralded as a revolution in thought, possibly comparable with that initiated by Copernicus, it was quickly attacked as groundless speculation, negating all known facts about the thickness and solidity of the earth's crust. As advocates and opponents joined the battle, some British scientists saw how it could help to solve geological problems and adopted a cautiously favorable attitude toward Wegener's basic idea of continental motion, although they disputed the details. In 1928, a British geologist proposed convection currents as the mechanism for splitting continents and rafting apart the fragments, thus providing a crucial element to the model that, decades later, would aid in the transformation of continental drift to plate tectonics. At the time of Wegener's death in 1930, his hypothesis remained under strong attack, yet support was well-established among Britain's independently-minded scientists.

Wegener's theory: The role of geophysics in its eclipse and triumph

Wegener's hypothesis of continental drift was based on a synthesis of world geological observations. Although there was much debate about the correctness of the geological interpretations, the chief objection to the theory came from the absence of a viable geophysical mechanism and in particular from the argument in favour of the mantle having finite strength. By about 1950 the hypothesis was widely rejected by geoscientists but soon after the development of palaeomagnetism provided what was needed to test it: a quantitative method of determining the position of the continents in the geological past. Comparisons of palaeomagnetic polar wandering curves from the different continents provided strong support for the essential ideas which Wegener had put forward. By the early 1960s the hypothesis of convection in the Earth's mantle made possible by solid state creep removed the basic geophysical objections to Wegener's theory. Sea floor spreading neatly complemented continental drift, and integrated into the concept of plate tectonics, has provided a framework in which much other geological and geophysical data fit.

New palaeomagnetic evidence fails to support rotation of western Newfoundland

Palaeomagnetic results from Ordovician to late Precambrian rocks in western Newfoundland are inconsistent with Wegener's hypothesis that the island has rotated 30° anticlockwise. Previous evidence apparently supporting this hypothesis is shown to be inconclusive.

Paleomagnetism of the Lower Cambrian Bradore sandstones, and the rotation of Newfoundland

Wegener proposed that Newfoundland has rotated 30 degrees anticlockwise relative to Labrador. We report here new paleomagnetic evidence bearing on this hypothesis, obtained from sandstones of the Lower Cambrian Bradore Formation on Canada Bay, Newfoundland. Isothermal remanence tests indicate that the entire natural remanence (NRM) of the samples resides in hematite. The mean NRM direction for 9 sites is D = 153°, I = +52°, α 95 = 15° , confirming R.F. Black's 1964 result from other Bradore exposures in northern Newfoundland, which he compared with rocks in New Brunswick. Although Black's data appeared to support Wegener's hypothesis, his samples had not been thermally treated, whereas thermal demagnetization of our samples led to isolation at 665°C of a very stable component misaligned with the NRM direction. The 665°C component probably was acquired through a C(hemical)RM and/or D(epositional)RM process by the time the rocks became consolidated. After structural correction, this component corresponds to a reverse paleomagnetic pole at 29°N,167°E ( dp = 3°, dm = 5°, 9 sites). Bradore sandstone from two sites located 50 km west of Canada Bay gave comparable (virtual) poles. These results are useful for a potential test of a post-Lower Cambrian rotation of western Newfoundland.

Sonic New Properties of Kelvin-Helmholtz Waves in an Atmosphere With and Without Condensation Effects

Abstract The stability and characteristics of Kelvin-Helmholtz waves in an atmosphere that may be saturated over some of its height are investigated analytically and numerically. It is shown that, if there is a temperature jump at the interface, the Wegener hypothesis, i.e., the assumption that stability boundary curves are loci of neutral waves travelling with phase velocity equal to the mean of the velocities of the regions above and below the discontinuity, is invalid. Instead, the stability boundary corresponds to the singular neutral modes with phase speed equal to the velocity in one or the other layer, depending on the sign of the temperature jump and the presence of saturation. Furthermore, the effect of saturation on the stability is found to be substantial. For the common case of a shallow saturated layer adjacent to the interface, the system is shown to behave essentially as if the temperature jump were smaller by an amount proportional to the mixing ratio and thickness. Finally, the validity o...

On Scientific Hypotheses and Authentic Knowledge in Modern Discoveries of General Regularities in Physical Geography

AbstractThe methodological aspects of the relationship between scientific hypothesis and authentic theory are examined with particular reference to the discoveries of regularities in the field of physical geography. A hypothesis is defined as a proposition whose basic content may be refuted as a result of further research; the basic content of authentic theory is beyond dispute, but may be further altered and refined. Instead of a traditional opposition of hypothesis to theory, the author recommends a broader approach treating both the formulation of a scientific hypothesis and the creation of a theory as discoveries of a theoretical character. According to this view, discoveries may be in the realm of hypothetical knowledge or in the area of authentic knowledge, depending on the weight of evidence. The Wegener hypothesis of continental drift is viewed as an example of a discovery in the realm of hypothetical knowledge; global regularities of heat-moisture relationships deriving from solar radiation are r...

Palaeomagnetic Evidence for the Ordovician Geomagnetic Pole Position

I HAVE obtained evidence which supports a pole position in the region of 165° E., 13° N. (antipole 15° W., 13° S.) on the present latitude–longitude grid and relative to the British Isles. This agrees with the palaeoclimatological evidence reported by Spjeldnaes1, whose studies, based chiefly on the global distribution of shallow water shell deposits, led him to suggest that the Ordovician climatic zones could be deduced from the faunal provinces and that polar ice caps existed during this period. Spjeldnaes1 infers a rotational pole lying in or west of Africa which would correspond to the palaeomagnetic pole at 15° W., 13° S. These data are not in conflict with Wegener's hypothesis of continental drift, for the positions of the climatic zones on either side of the Atlantic are improved by moving the continental blocks together1. There is little corresponding information for the 165° E., 13° N. pole because the data available for China are too few to say whether the palaeolatitude and palaeomagnetic latitude are in agreement. Spjeldnaes concluded from a consideration of Runcorn's2 palaeomagnetic polar wandering curves that a magnetic pole at about 165° E., not far from the Equator, in the region of 0°–25° north of it, would correlate well with the available data.

Fossil Diptera and Continental Drift

IT is well known that many plant and animal taxa have what has been termed an ‘Antarctic’ or ‘Antarctogaean’ distribution, that is, they are mainly or entirely restricted to southern Australia and/or New Zealand, southern South America, and, in some cases, South Africa. This has been accepted by many biogeographers as evidence of an ancient connexion between these land-masses, probably via the Antarctic continent. In particular, it is seen as strong evidence in favour of Wegener's hypothesis of ‘continental drift’, a theory now attaining some respectability in the eyes of the geophysicists1 who were formerly its principal opponents.

THE GEODETIC EVIDENCE CONCERNING WEGENER'S HYPOTHESIS

Twenty years ago there seemed to be many good reasons for supposing that Wegener's hypothesis of Continental Drift was untenable. There seemed to be unsurmountable objections to it from a point of view of a mechanism capable of causing tectonic movements of such magnitude; there was disagreement over the correspondence of the orogenic belts in the areas of the earth which are supposed formerly to have been united, as well as over other major geological factors; there was the gravest discordance between the known palaeontological facts and those demanded by the theory; after examination of the geodetic evidence, at least one distinguished geodesist pronounced that it was insufficient. General opinion to-day has perhaps changed and there now appears to be a marked tendency to recognise the cogency of some of Wegener's general arguments and to pay greater attention to the possibilities which he propounded, because it is becoming increasingly clear that the question of the arrangement and of the stability of the primary structural units of the Earth's surface, during geological time, is one of the fundamental problems of geology, as well as of all the allied subjects of geophysics, geomorphology, geodesy, palaeoclimatology and palaeontology. This is the writer's opinion, for what it is worth, after studying the considerable literature on this important and fascinating subject which has accumulated in the course of the past 30 years, during part of a recent leave spent in “browsing” round the Schools and libraries of Cambridge University.

THE GEODETIC EVIDENCE CONCERNING WEGENER'S HYPOTHESIS

Twenty years ago there seemed to be many good reasons for supposing that Wegener's hypothesis of Continental Drift was untenable. There seemed to be unsurmountable objections to it from a point of view of a mechanism capable of causing tectonic movements of such magnitude; there was disagreement over the correspondence of the orogenic belts in the areas of the earth which are supposed formerly to have been united, as well as over other major geological factors; there was the gravest discordance between the known palaeontological facts and those demanded by the theory; after examination of the geodetic evidence, at least one distinguished geodesist pronounced that it was insufficient. General opinion to-day has perhaps changed and there now appears to be a marked tendency to recognise the cogency of some of Wegener's general arguments and to pay greater attention to the possibilities which he propounded, because it is becoming increasingly clear that the question of the arrangement and of the stability of the primary structural units of the Earth's surface, during geological time, is one of the fundamental problems of geology, as well as of all the allied subjects of geophysics, geomorphology, geodesy, palaeoclimatology and palaeontology. This is the writer's opinion, for what it is worth, after studying the considerable literature on this important and fascinating subject which has accumulated in the course of the past 30 years, during part of a recent leave spent in “browsing” round the Schools and libraries of Cambridge University.

Distribution of Oceans and Continents--A Suggestion

Distribution of Oceans and Continents--A Suggestion

Structure of the earth's crust and the spreading of the continents

Research Article| October 31, 1936 Structure of the earth’s crust and the spreading of the continents BENO GUTENBERG BENO GUTENBERG Search for other works by this author on: GSW Google Scholar GSA Bulletin (1936) 47 (10): 1587–1610. https://doi.org/10.1130/GSAB-47-1587 Article history received: 07 Jul 1936 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation BENO GUTENBERG; Structure of the earth’s crust and the spreading of the continents. GSA Bulletin 1936;; 47 (10): 1587–1610. doi: https://doi.org/10.1130/GSAB-47-1587 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract INTRODUCTION: WEGENER’S THEORYAccording to the Wegener hypothesis, the continents originally formed a single block. This broke into sections in the Carboniferous, and, during the geologic periods that followed, the continents drifted apart. Wegener, as many others had done before him, originally conceived the idea that the similarity in the coast lines of Europe-Africa and America indicated connection previous to the Carboniferous. It is to his credit, however, that he investigated in detail all the possible consequences of this hypothesis. He considered especially the present-day relative movements of parts of the earth’s crust, and he started investigations of the movement of Greenland relative to Europe. He emphasized the importance of determining and explaining the changes in the land-bridge connections between the continents, which occurred from time to time, because of their bearing on the problem of continental origin and history. Similarities in the structure of certain regions, now far apart, . . . This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

The Lavas of Mauritius

The geology and physical geography of Mauritius formed the subject of a communication to the Geological Society by Major H. de Haga Haig in 1895, 1 which has been the basis of subsequent descriptions of the island in the Encyclopædia Britannica and elsewhere. Major Haig showed that Mauritius is formed of basaltic lavas and tuffs, and that several of the hills in the interior of the island are volcanic cones, some of them having well-preserved craters. His description of the lavas is inadequate from a petrographic standpoint, being based on megascopic characters only. The basalts are described as dolerites and diorites; by the latter term, horn-blende-basalt seems to be intended. The most arresting feature in Major Haig's account is the record of ‘ crystalline chloritic schist ’ on Mt. La Selle, near the middle of the island. Students of Wegener's hypothesis will recall that Wegener believed the volcanic islands of the great oceans to be fragments of the lithosphere, left behind by the westward-drifting continents. The apparent absence of continental types of rock such as granite and schist from these islands was explained by Wegener as a consequence of the thick veneer of lava acquired by the islands since they broke away from the mainland. Major Haig's record of chloritic schist on Mauritius seemed to offer striking confirmation of Wegener's view, and called for confirmation and amplification. I visited Mauritius in January, 1931, with the intention of making such observations as time would permit among the lavas, and with the special

Land-Bridges across the Atlantic and Pacific Oceans during the Kainozoic Era

My research work on the history of South America, its formation from several distinct land-masses and its relationship to other continents, pursued continuously since 1890, reached some degree of finality in my book on the Atlantic Ocean. As the results of these researches had not for many years received any recognition by geologists, it was particularly pleasing to me to find that in his presidential address on the same subject Prof. J. W. Gregory has expressed opinions which for the most part coincide with mine. In this most interesting account of his researches he brings together an astonishing number of facts, and in so doing arrives at the conclusion that until Miocene times the Atlantic Ocean was still spanned by an African-American land-bridge. This agrees with my conception of the conditions then prevailing, according to which the Upper Miocene beds of Entre Rios are the first in which marine mollusca, echinoderma, and selachia, derived from the northern and southern seas, mingle. Gregory, as well as C. Schuchert, rejects on geological grounds the drift theory of Wegener and A. L. Du Toit, as do all German geologists with whom I have been in contact. Wegener's hypothesis, so far as it relates to the Atlantic shores of Africa and South America, demands the permanence of the present form of these continents as far back as the Cretaceous epoch. Against this idea it must be noted that geology has never admitted the persistence of a long stretch of coast-line, 50 to 60 degrees

Anticipation of Wegener's Hypothesis

THE question of the bodily displacement of continental masses on the earth's surface has been the subject of considerable discussion among geologists and geophysicists in recent years.

Test of the Wegener Hypothesis by Means of Geodetic Data in India

Test of the Wegener Hypothesis by Means of Geodetic Data in India

Drifting continents: the Wegener hypothesis

(1928). Drifting continents: the Wegener hypothesis. Australian Geographer: Vol. 1, No. 1, pp. 60-62.