Expanding earth theory
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The Expanding earth theory is now obsolete attempt to explain the position and movement of continents on the surface of the Earth. It is has only an insignifanct following today, compared with the scientific consensus theory of plate tectonics.
An expanding earth model was developed in the 1960s, building upon emerging evidence for sea floor expansion and continental drift. The expanded earth theory (and plate tectonics) incorporates the appearance of new crustal material at mid-ocean ridges, but the process of subduction is largely absent in this model.
Very few geologists or geophysicists today support the expanded Earth. Many of those that remain are proponents of the ideas of the late Australian geologist S. Warren Carey. While Carey's ideas were popular for a time in the 1950s and 1960s, most workers in earth science believe that evidence collected over the last several decades supports a fixed size Earth, due to subduction, over the expanded Earth.
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[edit] Challenging the Extent of Subduction
Expanding Earth Theory scrutinizes the extent of subduction in maintaining a fixed size Earth, for several reasons:
- In order for subduction to cause the Earth's size to remain fixed, the same exact amount of crustal material appearing at the mid-ocean ridges must subsequently subduct back into the Earth. There exists, however, no known mechanism for such a correlation, nor is there any geological evidence binding such a relationship between the two processes.
- The mid-ocean ridges are considerably more vast in length and area than the known subduction zones and circle the entire globe in several configurations. In order for the crustal material appearing there to subduct equally into the known zones, some evidence of a bottle-neck pile-up of oceanic slabs should be visible nearing these subduction zones. Yet the entire ocean floor is smoothly surfaced, free of oceanic slab irregularities, indicating harmonious spreading unencumbered by such a process.
- The ocean floor areas on the "other side" of the subduction zones, facing the continental shelves, are the same age as the ocean floor areas on the subducting side, facing the mid-ocean ridges. Because subduction only occurs on one side of the zones, facing the mid-ocean ridges, the "other side" should show evidence of being much older, geologically, because it does not subduct. Yet, no such evidence is visible.
[edit] Physics of a Growing Earth
The primary objection to Expanding Earth Theory, as introduced by Professor of Geology Samuel Carey, and others, in the 1960s, centered around the lack of a process by which the Earth's mass could increase. This issue, along with the rise of the theory of Subduction, caused the scientific community to dismiss the geological evidence Carey and others presented. The evidence for continental matching, even on the Pacific facing sides became irrelevant, as did the claims that a smaller sized and lower gravity Earth facilitated the growth of dinosaurs to their relatively enormous size. Because, however, the proponents of this theory were unable to explain where the mass that causes Earth Growth comes from, it was dismissed for the theory that Subduction caused the Earth to remain at a fixed size.
[edit] Further reading
- Carey, S. Warren (1988). Theories of the earth and universe : a history of dogma in the earth sciences. Stanford, CA: Stanford University Press. ISBN 0-8047-1364-2.
- Michihei, HOSHINO (1998). The Expanding Earth evidence, causes and effects. Kanagawa, JAPAN: Tokai University Press. ISBN 4-486-03139-3.
[edit] External links
- The Expanded Earth
- Expanding Earth / The Evidence
- Keith Wilson's Expanding Earth Knowledge Co.
- Plate Tectonics and Expanding Earth
- Warren Carey, Last of the Giants
- Lawrence Meyer's Expanding Earth
- Growing Earth Consortium
- Video Explaining the Expanding Earth theory
