The division is based on differences in mechanical properties and in the method for the transfer of heat. The lithosphere is cooler and more rigid, while the asthenosphere is hotter and flows more easily.
Continental drift was a theory that explained how continents shift position on Earth's surface. Continental drift theory helps biogeographers to explain the disjunct biogeographic distribution of present-day life found on different continents but having similar ancestors. In particular, it explains the Gondwanan distribution of ratites and the Antarctic flora. continental drift A term, no longer used by geologists, that refers to the fact that continents are not stationary, but move across the Earth 's surface. Continental drift is one feature of the modern theory of plate tectonics.
Early history[ edit ] Abraham Ortelius Ortelius Theodor Christoph Lilienthal Alexander von Humboldt and Antonio Snider-Pellegrini Snider-Pellegriniand others had noted earlier that the shapes of continents on opposite sides of the Atlantic Ocean most notably, Africa and South Continental movement seem to fit together.
Kious described Ortelius' thoughts in this way: In his Manual of Geology Continental movement, Dana wrote, "The continents and oceans had their general outline or form defined in earliest time.
This has been proved with respect to North America from the position and distribution of the first beds of the Silurian — those of the Potsdam epoch. This suggested that the oceans were a permanent feature of the Earth's surface, and did not change places[ clarification needed ] with the continents.
In Mantovani's conjecture, this continent broke due to volcanic activity caused by thermal expansionand the new continents drifted away from each other because of further expansion of the rip-zones, where the oceans now lie.
This led Mantovani to propose an Expanding Earth theory which has since been shown to be incorrect. Although his proposed mechanism was wrong, he was the first to realize the insight that one of the effects of continental motion would be the formation of mountains, and attributed the formation of the Himalayas to the collision between the Indian subcontinent with Asia.
In the midth century, the theory of continental drift was referred to as the "Taylor-Wegener hypothesis",    although this terminology eventually fell out of common use. Wegener was the first to use the phrase "continental drift"  in German "die Verschiebung der Kontinente" — translated into English in and formally publish the hypothesis that the continents had somehow "drifted" apart.
Although he presented much evidence for continental drift, he was unable to provide a convincing explanation for the physical processes which might have caused this drift.
His suggestion that the continents had been pulled apart by the centrifugal pseudoforce Polflucht of the Earth's rotation or by a small component of astronomical precession was rejected, as calculations showed that the force was not sufficient. Rejection of Wegener's theory, s—s[ edit ] The theory of continental drift was not accepted for many years.
One problem was that a plausible driving force was missing.
Other geologists also believed that the evidence that Wegener had provided was not sufficient. It is now accepted that the plates carrying the continents do move across the Earth's surface, although not as fast as Wegener believed; ironically one of the chief outstanding questions is the one Wegener failed to resolve: He proposed in that the Earth's mantle contained convection cells which dissipated radioactive heat and moved the crust at the surface.
Continental crust is inherently lighter and its composition is different from oceanic crust, but both kinds reside above a much deeper " plastic " mantle.
Oceanic crust is created at spreading centersand this, along with subductiondrives the system of plates in a chaotic manner, resulting in continuous orogeny and areas of isostatic imbalance.
The theory of plate tectonics explains all this, including the movement of the continents, better than Wegener's theory. The fixists[ edit ] Hans Stille and Leopold Kober opposed the idea of continental drift and worked on a "fixist"  geosyncline model with Earth contraction playing a key role in the formation of orogens.
Bernauer correctly equated Reykjanes in Iceland with the Mid-Atlantic Ridge arguing with this that the floor of the Atlantic Ocean was undergoing extension just like Reykjanes. The idea was moonshine, I was informed. This would explain one, but only one, mountain building episode between any pair of continents; it failed to account for earlier orogenic episodes.
Second, masses floating freely in a fluid substratum, like icebergs in the ocean, should be in isostatic equilibrium in which the forces of gravity and buoyancy are in balance.The consequences of plate movement are easy to see around Krafla Volcano, in the northeastern part of Iceland.
Here, existing ground cracks have widened and new ones appear every few months. From to , numerous episodes of rifting (surface cracking) took place along the Krafla fissure zone. Continental drift was a theory that explained how continents shift position on Earth's surface.
Dino Dinosaur Paleobiology is a lesson course teaching a comprehensive overview of non-avian dinosaurs. Topics covered: anatomy, eating, locomotion, growth, environmental and behavioral adaptations, origins and extinction.
Lessons are delivered from museums, fossil-preparation labs and dig. Continental drift is the theory that the Earth's continents have moved over geologic time relative to each other, thus appearing to have "drifted" across the ocean bed.
The speculation that continents might have 'drifted' was first put forward by Abraham Ortelius in Continental drift theory helps biogeographers to explain the disjunct biogeographic distribution of present-day life found on different continents but having similar ancestors.
In particular, it explains the Gondwanan distribution of ratites and the Antarctic flora. Continental drift theory helps biogeographers to explain the disjunct biogeographic distribution of present-day life found on different continents but having similar ancestors. In particular, it explains the Gondwanan distribution of ratites and the Antarctic flora.