Difference between revisions of "Plate tectonics"

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Plate tectonics is a theory of geology that has been developed to explain the observed evidence for large scale motions of the Earth's crust. The theory encompassed and superseded the older theory of continental drift from the first half of the 20th century and the concept of seafloor spreading developed during the 1960s.
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{{merge from|Continental drift}}
  
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The outermost part of the Earth's interior is made up of two layers: above is the lithosphere, comprising the crust and the rigid uppermost part of the mantle. Below the lithosphere lies the asthenosphere. Although solid, the asthenosphere has relatively low viscosity and shear strength and can flow like a liquid on geological time scales. The deeper mantle below the asthenosphere is more rigid again. This is, however, due not to cooler temperatures but to high pressure.
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'''Plate tectonics''' is a geological model of the movement of [[continental plate]]s, known as [[Continental drift]], which explains how the [[Earth]] once had a [[Pangaea|single large land mass]] which broke into [[continent]]s that continued to separate, and that they still move slowly today.
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The lithosphere is broken up into what are called tectonic plates—in the case of Earth, there are seven major and many minor plates (see list below). The lithospheric plates ride on the asthenosphere. These plates move in relation to one another at one of three types of plate boundaries: convergent, divergent, and transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along plate boundaries. The lateral movement of the plates is typically at speeds of 0.66 to 8.50 centimeters per year.
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== Ocean floor mapping ==
  
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About two thirds of the Earth's surface lies beneath the oceans. Before the 19th century, the depths of the open ocean were largely a matter of speculation, and most people thought that the ocean floor was relatively flat and featureless. However, as early as the 16th century, a few intrepid navigators, by taking soundings with hand lines, found that the open ocean can differ considerably in depth, showing that the ocean floor was not as flat as generally believed. Oceanic exploration during the next centuries dramatically improved our knowledge of the ocean floor. We now know that most of the geologic processes occurring on land are linked, directly or indirectly, to the dynamics of the ocean floor.
  
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== Developing the Theory ==
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"Modern" measurements of ocean depths greatly increased in the 19th century, when deep-sea line soundings (bathymetric surveys) were routinely made in the Atlantic and Caribbean. In 1855, a bathymetric chart published by U.S. Navy Lieutenant Matthew Maury revealed the first evidence of underwater mountains in the central Atlantic (which he called "Middle Ground"). This was later confirmed by survey ships laying the trans-Atlantic telegraph cable. Our picture of the ocean floor greatly sharpened after World War I (1914–18), when echo-sounding devices—primitive sonar systems—began to measure ocean depth by recording the time it took for a sound signal (commonly an electrically generated "ping") from the ship to bounce off the ocean floor and return. Time graphs of the returned signals revealed that the ocean floor was much more rugged than previously thought. Such echo-sounding measurements clearly demonstrated the continuity and roughness of the submarine mountain chain in the central Atlantic (later called the Mid-Atlantic Ridge) suggested by the earlier bathymetric measurements.
  
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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. Most scientists had previously believed that the oceans have existed for at least four 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? Their answer to this question, which came after further exploration, would prove to be vital to advancing the concept of plate tectonics.
  
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Continental drift was hotly debated off and on for decades following Wegener's death before it was largely dismissed as being eccentric, preposterous, and improbable. However, beginning in the 1950s, a wealth of new evidence emerged to revive the debate about Wegener's provocative ideas and their implications. In particular, four major scientific developments spurred the formulation of the plate-tectonics theory: (1) demonstration of the ruggedness and youth of the ocean floor; (2) confirmation of repeated reversals of the Earth magnetic field in the geologic past; (3) emergence of the seafloor-spreading hypothesis and associated recycling of oceanic crust; and (4) precise documentation that the world's earthquake and volcanic activity is concentrated along oceanic trenches and submarine mountain ranges.  
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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  [[Denali]] (formerly known as [[Mount McKinley]]) 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.
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Ocean floor mapping
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About two thirds of the Earth's surface lies beneath the oceans. Before the 19th century, the depths of the open ocean were largely a matter of speculation, and most people thought that the ocean floor was relatively flat and featureless. However, as early as the 16th century, a few intrepid navigators, by taking soundings with hand lines, found that the open ocean can differ considerably in depth, showing that the ocean floor was not as flat as generally believed. Oceanic exploration during the next centuries dramatically improved our knowledge of the ocean floor. We now know that most of the geologic processes occurring on land are linked, directly or indirectly, to the dynamics of the ocean floor.
+
== Magnetic Striping and Reversals ==
  
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"Modern" measurements of ocean depths greatly increased in the 19th century, when deep-sea line soundings (bathymetric surveys) were routinely made in the Atlantic and Caribbean. In 1855, a bathymetric chart published by U.S. Navy Lieutenant Matthew Maury revealed the first evidence of underwater mountains in the central Atlantic (which he called "Middle Ground"). This was later confirmed by survey ships laying the trans-Atlantic telegraph cable. Our picture of the ocean floor greatly sharpened after World War I (1914-18), when echo-sounding devices -- primitive sonar systems -- began to measure ocean depth by recording the time it took for a sound signal (commonly an electrically generated "ping") from the ship to bounce off the ocean floor and return. Time graphs of the returned signals revealed that the ocean floor was much more rugged than previously thought. Such echo-sounding measurements clearly demonstrated the continuity and roughness of the submarine mountain chain in the central Atlantic (later called the Mid-Atlantic Ridge) suggested by the earlier bathymetric measurements.
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Beginning in the 1950s, scientists, using [[magnetism|magnetic]] instruments (magnetometers) adapted from airborne devices developed during [[World War II]] to detect [[submarine]]s, began recognizing odd magnetic variations across the ocean floor, showing reversals in the Earth's magnetic field over its history. This finding, though unexpected, was not entirely surprising because it was known that basalt—the iron-rich, volcanic rock making up the ocean floor—contains a strongly magnetic mineral (magnetite) and can locally distort compass readings. This distortion was recognized by Icelandic mariners as early as the late 18th century. More important, because the presence of magnetite gives the basalt measurable magnetic properties, these newly discovered magnetic variations provided another means to study the deep ocean floor.
  
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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? The answer to this question, which came after further exploration, would prove to be vital to advancing the concept of plate tectonics.
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== Explanations of continental drift ==
  
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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.
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The breaking up of one land mass into the separate continents was first proposed by the [[France|French]] [[creation scientist]] [[Antonio Snider]] in 1859,<ref name="Snider">Batten, Don, et. al., The Creation Answers Book, chapter 11: [http://creationontheweb.com/images/pdfs/cabook/chapter11.pdf What about continental drift?], p. 157, 2007</ref> who astutely observed an almost perfect match between the coastlines of western [[Africa]] and eastern [[South America]], which suggested they had once been joined. The idea was later taken up by [[Alfred Wegener]] in the 1930s."<ref name=wcd>[http://www.scientus.org/Wegener-Continental-Drift.html Wegener and Continental Drift Theory]</ref> [[Atheists]] mocked the concept for about 100 years (see [[scientific bias]]), until finally accepting its truth in the 1960s.<ref name="Snider" />
  
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Although Snider and Wegener did not have an explanation of the cause of continental drift, the rigid discipline of [[creation science]] allied with [[Faith and science|faith and logic]] eventually enabled creation scientist to interpret [[Biblical scientific foreknowledge]] in order to explain how a relatively recent cataclysmic event caused the separation of the still-moving continents from one land mass. Genesis 1:9-10 describes how all of dry land was in one place.<ref>http://www.christiananswers.net/q-aig/aig-c001.html#1</ref>  The continental drift occurring during the [[Great Flood]] when the earth was divided (Genesis 10:25).
  
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== Magnetic Striping and Reversals ==
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Dr. [[John Baumgardner]], a geophysicist then with the Los Alamos National Laboratory, developed a sophisticated 3D computer model of plate tectonics, and believes that his model works best as a rapid process during the Flood.<ref>Batten, Don, et. al., [http://www.creationontheweb.com/images/pdfs/cabook/chapter11.pdf What about continental drift?] Chapter 11 of the Creation Answers Book, 2007.</ref>
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Beginning in the 1950s, scientists, using magnetic instruments (magnetometers) adapted from airborne devices developed during World War II to detect submarines, began recognizing odd magnetic variations across the ocean floor. This finding, though unexpected, was not entirely surprising because it was known that basalt -- the iron-rich, volcanic rock making up the ocean floor-- contains a strongly magnetic mineral (magnetite) and can locally distort compass readings. This distortion was recognized by Icelandic mariners as early as the late 18th century. More important, because the presence of magnetite gives the basalt measurable magnetic properties, these newly discovered magnetic variations provided another means to study the deep ocean floor.
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The creation scientist Dr. [[Russell Humphreys]] predicted that magnetic reversals would be found with time frames of days or weeks, from having occurred during the Flood. In an example of a successful creation science prediction, scientists subsequently found magnetic reversals that had taken place over the space of 15 days.<ref>Snelling, Andrew A., [http://www.creationontheweb.com/content/view/1233/ Fossil magnetism reveals rapid reversals of the earth’s magnetic field], ''Creation'' 13(3):46–50, June 1991.</ref>
  
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==Biblical View==
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Atheistic [[science]] rejects the Biblical truth and instead applies [[liberal logic]] to concoct a [[junk science]] explanation based on the present observed rate of continental drift, which came to the tenuous conclusion that the continents that we know today were part of a single land mass about 250 million years ago.
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Genesis states "And God said, Let the waters under the heaven be gathered together unto one place, and let the dry land appear: and it was so. And God called the dry land Earth; and he gathering together of the waters called He called Seas" (1:9-10). It further states that "in the days of Peleg the earth was divided" (Genesis 10:25). Creationists have pointed out that these passages support the notion of plate tectonics, although the speed at which the continents moved apart must have been much faster during the last 6000 years to account for the distances seen today<ref>http://www.jpdawson.com/pelgnet/pelchap1/PELCHAP1.html</ref>.  It is also worthy of note that modern Israel sits at the proposed center of the supercontinent Pangea, indicating that it was indeed the center of the Earth at the time of creation and that the continents are essentially drifting away from that point today <ref>1.  www.jpdawson.com/pelgnet/pelchap1/</ref>
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==References==
 
==References==
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1.  www.jpdawson.com/pelgnet/pelchap1/
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{{reflist|2}}
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[[category:geology]]
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[[Category:Geology]]

Revision as of 13:57, August 9, 2016

It has been suggested that Continental drift be merged with this article or section. (Discuss)

Plate tectonics is a geological model of the movement of continental plates, known as Continental drift, which explains how the Earth once had a single large land mass which broke into continents that continued to separate, and that they still move slowly today.

Ocean floor mapping

About two thirds of the Earth's surface lies beneath the oceans. Before the 19th century, the depths of the open ocean were largely a matter of speculation, and most people thought that the ocean floor was relatively flat and featureless. However, as early as the 16th century, a few intrepid navigators, by taking soundings with hand lines, found that the open ocean can differ considerably in depth, showing that the ocean floor was not as flat as generally believed. Oceanic exploration during the next centuries dramatically improved our knowledge of the ocean floor. We now know that most of the geologic processes occurring on land are linked, directly or indirectly, to the dynamics of the ocean floor.

"Modern" measurements of ocean depths greatly increased in the 19th century, when deep-sea line soundings (bathymetric surveys) were routinely made in the Atlantic and Caribbean. In 1855, a bathymetric chart published by U.S. Navy Lieutenant Matthew Maury revealed the first evidence of underwater mountains in the central Atlantic (which he called "Middle Ground"). This was later confirmed by survey ships laying the trans-Atlantic telegraph cable. Our picture of the ocean floor greatly sharpened after World War I (1914–18), when echo-sounding devices—primitive sonar systems—began to measure ocean depth by recording the time it took for a sound signal (commonly an electrically generated "ping") from the ship to bounce off the ocean floor and return. Time graphs of the returned signals revealed that the ocean floor was much more rugged than previously thought. Such echo-sounding measurements clearly demonstrated the continuity and roughness of the submarine mountain chain in the central Atlantic (later called the Mid-Atlantic Ridge) suggested by the earlier bathymetric measurements.

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. Most scientists had previously believed that the oceans have existed for at least four 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? Their answer to this question, which came after further exploration, would prove to be vital to advancing the concept of plate tectonics.

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 Denali (formerly known as Mount McKinley) 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.

Magnetic Striping and Reversals

Beginning in the 1950s, scientists, using magnetic instruments (magnetometers) adapted from airborne devices developed during World War II to detect submarines, began recognizing odd magnetic variations across the ocean floor, showing reversals in the Earth's magnetic field over its history. This finding, though unexpected, was not entirely surprising because it was known that basalt—the iron-rich, volcanic rock making up the ocean floor—contains a strongly magnetic mineral (magnetite) and can locally distort compass readings. This distortion was recognized by Icelandic mariners as early as the late 18th century. More important, because the presence of magnetite gives the basalt measurable magnetic properties, these newly discovered magnetic variations provided another means to study the deep ocean floor.

Explanations of continental drift

The breaking up of one land mass into the separate continents was first proposed by the French creation scientist Antonio Snider in 1859,[1] who astutely observed an almost perfect match between the coastlines of western Africa and eastern South America, which suggested they had once been joined. The idea was later taken up by Alfred Wegener in the 1930s."[2] Atheists mocked the concept for about 100 years (see scientific bias), until finally accepting its truth in the 1960s.[1]

Although Snider and Wegener did not have an explanation of the cause of continental drift, the rigid discipline of creation science allied with faith and logic eventually enabled creation scientist to interpret Biblical scientific foreknowledge in order to explain how a relatively recent cataclysmic event caused the separation of the still-moving continents from one land mass. Genesis 1:9-10 describes how all of dry land was in one place.[3] The continental drift occurring during the Great Flood when the earth was divided (Genesis 10:25).

Dr. John Baumgardner, a geophysicist then with the Los Alamos National Laboratory, developed a sophisticated 3D computer model of plate tectonics, and believes that his model works best as a rapid process during the Flood.[4]

The creation scientist Dr. Russell Humphreys predicted that magnetic reversals would be found with time frames of days or weeks, from having occurred during the Flood. In an example of a successful creation science prediction, scientists subsequently found magnetic reversals that had taken place over the space of 15 days.[5]

Atheistic science rejects the Biblical truth and instead applies liberal logic to concoct a junk science explanation based on the present observed rate of continental drift, which came to the tenuous conclusion that the continents that we know today were part of a single land mass about 250 million years ago.

References

  1. ↑ 1.0 1.1 Batten, Don, et. al., The Creation Answers Book, chapter 11: What about continental drift?, p. 157, 2007
  2. ↑ Wegener and Continental Drift Theory
  3. ↑ http://www.christiananswers.net/q-aig/aig-c001.html#1
  4. ↑ Batten, Don, et. al., What about continental drift? Chapter 11 of the Creation Answers Book, 2007.
  5. ↑ Snelling, Andrew A., Fossil magnetism reveals rapid reversals of the earth’s magnetic field, Creation 13(3):46–50, June 1991.
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