Mobilism

Mobilism

 

a theory that posits large (up to several thousand km) horizontal displacements of the continental blocks of the earth’s crust (the lithosphere) relative to one another and to the poles in the course of geological time. Mobilism is opposed to fixism, the hypothesis that denies such displacement and assigns the chief role in the development of the earth’s crust to vertical movements. The idea that continents are mobile arose in the 19th century, but the scientific hypothesis of mobilism was first formulated in 1912 by the German geophysicist A. Wegener, who called it the theory of continental drift.

The modern version of mobilism, known as new global tectonics, or plate tectonics, is largely based on studies of the relief of the ocean floor, magnetic fields of the oceans, and paleomagnetism= According to these theories, there is a slow displacement (averaging 1–5 cm per year) of the monolithic plates, including not only the continental blocks but also the vast areas of oceanic crust adjacent to them and the top layer of the mantle. The plates move away from the midocean ridges toward the young folded belts (the Andes and Himalayas) and the island arcs. There, at the contact of the two mobile plates, the leading edge of one of them plunges to depths of up to 700 km under the other along inclined faults that have high levels of seismic activity. Folds and overthrusts form in the continental crust of the other plate through compression. Rifts form at the back of the moving blocks, along the axis of the midocean ridges. The rise of matter from the upper mantle into the “opening” formed when the plates move apart and the subsequent extrusion of basalt lavas form a new layer of the crust in the rift zone, thereby expanding the ocean floor.

Paleotectonic reconstructions have been proposed on the basis of the similarity in the geological structure of the disconnected parts of the Paleozoic continents of Gondwanaland and Laurasia and the matching contours of their continental slopes. Gondwanaland encompassed South America, Africa, the Indian subcontinent, Australia, and Antarctica, and Laurasia comprised North America, Europe, and the northern half of Asia. These reconstructions are reinforced by paleoclimatic and paleomagnetic findings showing that the different parts of Gondwanaland were much closer to the south pole at the end of the Paleozoic than they are today and that North America lay next to Europe. The movements that occurred during the Mesozoic and Cenozoic resulted in the almost complete disappearance of the geosynclinal ocean Tethys and the formation of the Indian and Atlantic oceans. Continental mobility is generally thought to be caused by convection currents of mantle material.

REFERENCES

Gutenberg, B. Fizika zemnykh nedr. Moscow, 1963. (Translated from English.)
Takeuchi, H., S. Uyeda, and H. Kanamori. Dvizhutsia li materiki? Moscow, 1970. (Translated from English.)
Dreif kontinentov. Moscow, 1966. (Collection of articles translated from English.)
Kropotkin, P. N. Evoliutsiia Zemli. Moscow, 1964.
Okean. Moscow, 1971. (Translated from English.)

P. N. KROPOTKIN

References in periodicals archive ?
Again, this is easy to say, but now, as we are racing full tilt into the Age of Mobilism, it is easy to see how to empower each and every student, to enable each and every learner to engage in a learn-by-doing pedagogy, 24/7, inside the classroom and outside the classroom.
Another "mobilism" for Byron's freewheeling insincerities is "satanism." McGann complains that
McGann might have granted this when he minted yet another mobilism. In "Byron and the Poetry of Deception," he re-christens the poet's mobility "Byron's feminine brain." Here, McGann modulates from an accusatory tone about Byron's contradictions to a more sympathetic one.
For this critic, the unconscious metaphor or mobilism for nihilism is "Byron's fictions of reality." Manning discerns that the poet's contradictory contexts and moods originate in British empiricism (230-35).
"Education in the Age of Mobilism" took place on Nov.
But rather than calling it the "Post-PC Era," which is a negative way to name it, let's call it what it is: the Age of Mobilism. What's unique about this new Age of Mobilism is the use of technology to meet the deep-seated human need to be connected.
In the vanguard, ushering in the Age of Mobilism, are today's youth.
You read it here first: Tablets are running a lovely but second-place race in the Age of Mobilism.