Plate tectonics
From CreationWiki, the encyclopedia of creation science
Plate Tectonics is a widely-accepted model used to explain the configuration of the Earth's outermost rocky layer, the crust, which exists as a number of puzzle-piece-like plates. We now know that there are seven major crustal plates, subdivided into a number of smaller plates. They are about 80 kilometers thick, all in constant motion relative to one another, at rates varying from 10 to 130 millimeters per year.
Most of the geological activity - mountain building, rift valleys, volcanoes, earthquakes, faulting - is due to different types of interaction at plate boundaries.[1]
These plates meet at boundaries where either:
- One plate subducts under another, diving into the mantle
- Two plates emerge from a rift, traveling in opposite directions
- Two plates slide past each other in opposite directions
Plate tectonics is now the mechanism used to support the long-standing view of continental drift, which purports the migration of continents to their present location following the breakup of a single landmass known as Pangea.
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History
The concept of plate tectonics has revolutionized thinking in the Earth sciences in the last 10 years and combines many of the ideas about continental drift (originally proposed in 1912 by Alfred Wegener in Germany) and sea-floor spreading (suggested originally by Harry Hess of Princeton University).[1]
Plate activity
The world's earthquakes and volcanoes are not randomly distributed over the Earth's surface. They tend to be concentrated in narrow zones called hot spots. The theory of plate tectonics tells us that the Earth's rigid outer shell (lithosphere) is broken into a mosaic of oceanic and continental plates which can slide over the plastic aesthenosphere, which is the uppermost layer of the mantle. The plates are in constant motion. Where they interact, along their margins, important geological processes take place, such as the formation of mountain belts, earthquakes, and volcanoes.[1]
The lithosphere covers the whole Earth. Therefore, ocean plates are also involved, more particularly in the process of sea-floor spreading. This involves the midocean ridges which are a system of narrow submarine cracks that can be traced down the center of the major oceans. The ocean floor is being continuously pulled apart along these midocean ridges. Hot volcanic material rises from the Earth's mantle to fill the gap and continuously forms new oceanic crust. The midocean ridges themselves are broken by offsets know as transform faults.[1]
Supporting evidence
In particular, four major scientific developments spurred the formulation of the plate-tectonics theory:
- Demonstration of the ruggedness and youth of the ocean floor
- Confirmation of repeated reversals of the Earth magnetic field in the geologic past
- Emergence of the seafloor-spreading hypothesis and associated recycling of oceanic crust
- Precise documentation that the world's earthquake and volcanic activity is concentrated along oceanic trenches and submarine mountain ranges.[2]
Youthful ocean flood
In the 1950s, oceanic exploration greatly expanded. Data gathered by oceanographic surveys conducted by many nations led to the discovery that a great mountain range on the ocean floor virtually encircled the Earth. Called the global mid-ocean ridge, this immense submarine mountain chain -- more than 50,000 kilometers (km) long and, in places, more than 800 km across -- zig-zags between the continents, winding its way around the globe like the seam on a baseball. Rising an average of about 4,500 meters(m) above the sea floor, the mid-ocean ridge overshadows all the mountains in the United States except for Mount McKinley (Denali) in Alaska (6,194 m). Though hidden beneath the ocean surface, the global mid-ocean ridge system is the most prominent topographic feature on the surface of our planet.[2]
Geomagnetic reversals
- Main Article: Geomagnetic reversals
The continental drift theory draws strong support from paleomagnetic readings of the ocean flood that have revealed a striped pattern of field reversals indicating that the flood has spread outward from the mid-oceanic ridge. The movement of continental plates can also explain the existence of earthquakes and the so-called Ring of Fire around the Pacific.
Recycling oceanic crust
In 1947, seismologists on the U.S. research ship Atlantis found that the sediment layer on the floor of the Atlantic was much thinner than originally thought. Scientists had previously believed that the oceans have existed for at least 4 billion years, so therefore the sediment layer should have been very thick. Why then was there so little accumulation of sedimentary rock and debris on the ocean floor?[2]
While the simplest and most obvious explanation for minimal seaflood sediment is that the earth is young, geologists hold fast to philosophical naturalism and the belief that the Earth is billions of years old.
Uniformitarian geologists believe that red-hot magma is constantly squeezed up from the mantle through rifts in the ocean floor. As new magma is squeezed in, the older crust is moved out from the midocean ridge like a conveyor belt. When adjacent plates collide due to this outward movement, some plates are forced downward under others causing the sedimentary rock to be "recycled".[3]
Continental drift
- Main Article: Continental drift
The continental drift theory purports that plate tectonics are responsible for the migration of continents to their present location following the breakup of a single landmass known as Pangea. The theory was developed primarily due to the similarity in shape of continental shorelines, such as that of South America and Africa, which causes them to appear as though they were once joined together. Supporters also assert that similar rock formations and organisms can also be found on coasts that are thought to have once been adjoined.
Before the advent of plate tectonics, some people already believed that the present-day continents were the fragmented pieces of preexisting larger landmasses ("supercontinents"). The diagrams at right show the break-up of the supercontinent Pangaea (meaning "all lands" in Greek), which figured prominently in the theory of continental drift -- the forerunner to the theory of plate tectonics.[4]
Catastrophic plate tectonics
- Main Article: Catastrophic plate tectonics
Dr. Baumgardner has created a computer model for catastrophic plate tectonics, and has presented detailed papers about his catastrophic plate tectonics model as the mechanism for the Genesis global flood. Baumgardner's model is illustrated in the 27 minute documentary titled: In the Beginning: Catastrophic Plate Tectonics and the Genesis Flood, which was produced by Keziah and may be previewed online.
References
- ↑ 1.0 1.1 1.2 1.3 Earthquakes and Plate Tectonics by the U.S. Geological Survey, Earthquake Hazards Program.
- ↑ 2.0 2.1 2.2 The Dynamic Earth: The Story of Plate Tectonics Chapter 2: Developing the Theory. by Jacquelyne Kious and Robert Tilling. U.S. Geologic Survey
- ↑ Rift in the Ocean Floor by the U.S. Geological Survey, Earthquake Hazards Program.
- ↑ The Dynamic Earth: The Story of Plate Tectonics Chapter 1: Historical Perspective. by Jacquelyne Kious and Robert Tilling. U.S. Geologic Survey
External links
- AiG's Forum on Catastrophic Plate Tectonics Ex Nihilo Technical Journal 16(1):57 April 2002
- Catastrophic plate tectonics: the geophysical context of the Genesis Flood by John Baumgardner
- Catastrophic Plate Tectonics: The Physics Behind the Genesis Flood by John Baumgardner of the, Proceedings of the Fifth International Conference on Creationism, R. L. Ivey, Jr., Editor, Creation Science Fellowship, Pittsburgh, PA, 113-126, 2003
- Is catastrophic plate tectonics part of Earth history? by Michael Oard
See Also
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