Douglas C. Face

Professor Nicholson

Composition II

November 28 2007

Atlantis Could Have Really Disappeared:

        The legend of Atlantis is a legend that most Americans have heard of. Few people know where the story of Atlantis really came from. The first person to ever write about Atlantis was a Greek philosopher named Plato (Christopher). Plato lived from 427-347 BCE. Plato was "the son of wealthy and influential Athenian parents" as well as a "student of Socrates" (Kemerling).

The Origin of the Story of Atlantis

        The story about Atlantis was very old when it came to Plato. According to "Timaeus," It was handed down from Plato’s great great great great grandfather Dropides who received the story from Solon, "the wisest of the seven sages" (Plato). Solon received the story from Egyption Priests (Keyes). The story eventually reached Critias, who was Plato’s great grandfather (Keyes). Critias told Socrates, who told Plato. Atlantis was briefly mentioned in "Timaeus" as recorded by Plato and later in great detail in "Critias" also recorded by Plato. The "Timaeus" and "Critias" Dialogues are the first written record of the story of Atlantis known to exist (Keyes). The length of time and the chain of ancestors that the story had to go through leaves room for unintentional errors to enter the story. The possibility that the story of Atlantis contains errors, or that it might be entirely made up, has no bearing on whether an island can disappear. I am trying to neither prove nor disprove the existance of Atlantis. I am merely trying to show that the destruction and disappearance of an island such as Atlantis is physically possible.

Critias’s Description of the size of Atlantis

        Critias’s description of Atlantis was that of a huge island. In fact, according to Critias, Atlantis was over seven times larger than Hawaii. Hawaii is only 10,932 square miles ("How Big"). In fact, "the largest atoll structure of the world is the Great Chagos Bank in the Indian Ocean," which is approximately 13,000 square kilometers ("Atoll"). That translates to about 5,019.33 square miles ("Measurement"). The largest atoll structure in the world today is approximately 1/15^{th the size of Critias’s description of Atlantis.}

        According to Plato, Critias said that the island of Atlantis was 3000 stadia long and 2000 stadia wide (Plato). That would mean that the island of Atlantis was 6,000,000 square stadia. That translates to approximately 79,384.85 square miles ("Measurement"). The state of Nebraska is 77,358 square miles ("How Big"). According to Critias, Atlantis was larger than the state of Nebraska.

        There was a canal system on Atlantis. Critias said that it was "ten thousand stadia in length" (Plato). Length in this case referring to the entire canal system, not a canal that was a straight line ten thousand stadia long. According to Plato, Critias told Socrates that the width of the canal system was "a stadium everywhere", meaning that the canals were all a stadium wide. A Roman stadium is equal to 0.997804610318332 Greek stadia, which is approximately 607 feet ("Measurement"). Taking that into consideration the surface area of the canal system alone was 10,000 square stadia or about 132 square miles ("Measurement"). That is four square miles less than two Washington D.C.’s. Washington D.C. is sixty-eight square miles ("How Big").

        There is also a potential problem with the size of Critias description of Atlantis. Critias told of an Island that was at least fifteen times larger than any atoll on earth. There is a theory that the story of Atlantis started out in Egypt and that in the translation to Greek, the symbol for "100" was translated as "1000" (Dankenbring). If this theory is correct it would throw all of the calculations off by a factor of ten changing the size of Atlantis from around 79,000 square miles to around 7,900 square miles, putting it in a more realistic size range to be an atoll. If Atlantis were an atoll, then its possible method of destruction would fit with the explanation Critias gave of how Atlantis disappeared.

How Atlantis Disappeared

        Critias says that after a great battle, "violent earthquakes and floods" occurred and "in a single day and night of misfortune all your warlike men in a body sank into the earth, and the island of Atlantis in like manner disappeared in the depths of the sea" (Plato).

        It is possible that Atlantis was built on a dormant volcano called an atoll. The earthquakes described by Critias could cause an island to disappear through a process called subduction. Critias goes on to say that the sea in front of the Pillars of Heracles was impassible after the sinking of Atlantis "because there is a shoal of mud in the way; [sic] and this was caused by the subsidence of the island." (Plato). Both the sinking of an island and the sediment could be caused by the type of earthquake that is the most probable in the ocean. When two huge oceanic plates push into each other it is common for them to push downward and cause a trench. In order to explain how subduction occurs I will give a brief lesson on the cause of earthquakes and the formation of volcanoes caused by earthquakes.

Earthquakes

        According to the article, This Dynamic Earth: The Story of Plate Tectonics – Historical Perspective by the United States Department of the Interior U.S. Geological Survey, Earthquakes are caused by the collision of huge plates. In 1912 Alfred Wegener published two articles on continental drift. After the publication of Wegener’s articles, the scientific theory of continental drift started to be taken seriously. Mr. Wegener proposed that "around 200 million years ago, the supercontinent Pangaea began to split apart" (This Dynamic). Pangaea was one huge continent made up of all of the Earth’s current continents. Pangaea broke up into two huge land masses, a southern continent called Gondwanaland and a northern continent called Laurasia. Over the preceding centuries these continents continued to be pulled apart by continental drift. The movement continues today.

        The "theory of continental drift" led "to the development of the theory of plate tectonics" (This Dynamic). The meaning of plate tectonics comes from two places. The word "plate" in geological terms "is a large, rigid slab of solid rock" (This Dynamic). "The word tectonics comes from the Greek root ‘to build’" (This Dynamic). The term Plate tectonics "refers to how the Earth’s surface is built of plates" (This Dynamic).

How the Continents Move

        Scientists at the turn of the 20th century "determined that our planet is made up of three main layers" (This Dynamic). The Earth is made up of the "crust, mantle, and core" (This Dynamic). The crust beneath the continents is about thirty kilometers thick. At the bottom of the ocean the crust is about five kilometers thick. Under some of the larger mountain ranges, the crust can be as much as a hundred kilometers thick (This Dynamic).

        Between the crust and the core is "a dense, hot layer of semi-solid rock approximately 2,900 km thick." This layer is called the mantle. The core is comprised of two parts, one solid and one liquid (This Dynamic). Further description of the mantle is needed to explain the movement of the continents.

        "The Earth’s internal structure influences plate tectonics" (This Dynamic). There are two basic parts of the mantle. The upper part which is closer to the crust "is cooler and more rigid than the deeper mantle" (This Dynamic). The upper and lower parts of the mantle "form a rigid layer of rock called the Lithosphere" (This Dynamic). The lithosphere is thinner in volcanic areas and under the ocean (This Dynamic). The lithosphere is made up of several moving plates. These plates "contain the world’s continents and oceans" (This Dynamic).

        There "is a relatively narrow, mobile zone in the mantle" (This Dynamic). This zone is sometimes subjected to extremely high levels of heat. This zone is called the asthenosphere and sometimes due to the extreme heat the asthenosphere gets soft and can flow (This Dynamic). "The rigid lithosphere is thought to ‘float’ or move about on the slowly flowing asthenosphere" (This Dynamic). This causes the tectonic plates to move.

        In a different article by the Geological Survey by the United States Department of the Interior, we read "Plate-tectonic forces" are most easily noticed in "narrow zones" called plate boundaries (Understanding). There are four types of plate boundaries but only two of them are involved in the formation of an island. The two plate boundaries that have the most visible effect on the Earth’s surface are "Divergent boundaries" and "Convergence boundaries" (Understanding).

        Divergent boundaries occur as two plates pull away from each other. As the plates move away from each other, weak spots are created where magma pushes up and forms new crust (Understanding).

        Convergence boundaries occur when two plates slam into each other (Understanding). This is what is considered a typical earthquake. When two continental plates push against each other, the result is that one plate moves up and one plate moves down (Understanding). A convergence of two continental plates can cause non-volcanic mountains to form. The upward movement of a plate can cause a visible rise in the Earth’s surface of several feet in just a few seconds or several thousand feet over millions of years (Understanding).

        When two oceanic plates or an oceanic plate and a continental plate converge, the plates usually move down causing a subduction. This can cause deep trenches on the ocean floor. Oceanic-continental convergence can cause volcanic eruptions. Over years these eruptions can build up on the ocean floor and eventually form volcanic mountains that rise out of the oceans (Understanding). This is the beginning of how an atoll is formed.

The Formation of a Volcanic Island Known as an Atoll

        While on his scientific fact finding mission, Charles Darwin realized that some islands are formed by volcanic activity (Darwin). An island is formed when a volcano forms under water and eventually breaches the waters surface. According to the article Volcanoes by the United States Department of the Interior U.S. Geological Survey, there are several types of volcanoes. The "cinder cone volcano" and the "shield volcano" are the two most likely to form an atoll.

        A cinder cone volcano is "built from particles and blobs of congealed lave ejected from a single vent. As the gas-charged lava is blown violently into the air, it breaks into small fragments that solidify and fall as cinders around the vent to form a circular oval cone" (Volcanoes).

        A shield volcano is "built almost entirely of fluid lava flows." Mauna Loa in Hawaii is an example of a shield volcano. Whenever the pressure gets too high in an active shield volcano, molten rock called lava flows out of "a central summit vent, or a group of vents" (Volcanoes). This lava builds up over hundreds of years to form a volcanic mountain.

        When a volcano forms in the ocean, it can rise significantly above sea level. Mauna Loa rises 28,000 feet off of the sea floor and protrudes "13,677 feet above sea level" (Volcanoes).

        Sometimes a volcano may just stop erupting. When a volcano no longer erupts, it is said to be dormant. When a volcano is dormant it does not mean that it can never erupt again. When a volcano is dormant for many years, life begins to form on and around it. Darwin realized that some of the islands that he saw while on the Beagle were of volcanic origin. The volcanoes had risen out of the water and coral had begun to grow and form a reef around them (Darwin).

        Sometimes the "magma chamber" of a volcano becomes "nearly empty" this is caused by an eruption that ejects most of the magma, which is what lava is called before it reaches the surface, from the chamber. With the magma chamber empty, the weight of the volcano causes it to start collapsing into itself ("Kinds of").

        Over time as the volcano collapses into itself it slowly sinks below the surface of the water. If enough time has elapsed for a coral reef to form around the volcano before it collapses, the coral reef can remain after the volcano has disappeared. Coral can continue to live in water as deep as one hundred meters (Morris). If the volcano collapses slowly enough, the coral can continue to grow. A coral reef can keep growing new coral on top of dead coral as long as it is able to get sunlight. If the volcano collapses too fast the coral reef does not get enough sunlight and it dies. An atoll is formed when the coral reef grows around the volcano and the volcano sinks slowly enough for the coral to continue to grow (Darwin).

The Sinking of an Island

        If Atlantis were built on an atoll that would mean that it was built on a dormant volcano. A dormant volcano can erupt if the pressure gets high enough inside of it. In A.D. 79 Mount "Vesuvius had been dormant for centuries" before the famous eruption "that buried the cities of Pompeii and Stabiae" ("Vesuvius"). If Atlantis was built on a volcano it is possible for the volcano to have erupted in a violent explosion that could have blown the entire top off of the island. If someone were to sail past where Atlantis had been it just might look like it sank. This however would have caused a huge cloud that would have been able to be seen for miles.

        The description of the destruction of Atlantis as given by Critias did not involve a volcanic cloud. Critias’s story did involve earthquakes, and Critias used the phrase "this was caused by the subsidence of the island" (Plato). This leads me to believe that the island that Atlantis was built on could have been a shield volcano. A shield volcano can be formed when two oceanic plates collide causing a subduction. As stated above, an undersea earthquake that causes a subduction causes a weakness in the Earth’s surface and magma pushes through becoming lava. Over time this builds the volcano. The important part here is to realize that the original cause of the volcano was subduction. If the plates moved enough and the subduction occurred right below an island, the island itself could sink. As I stated above, Critias used the plural word "earthquakes" and the phrase "in a single day and night" (Plato). This implies that there was more than one earthquake in approximately a twenty-four hour period. He also said that the place where Atlantis had been was now "impassable and impenetrable, because there is a shoal of mud in the way" This would make sense because Atlantis didn’t sink like a ship might sink; it settled when the land that it was sitting on was forced downward and it no longer had a solid foundation. If the earthquakes that occurred were strong enough to force that much land down, they would surly have caused tsunamis. According to the article "Life of a Tsunami," the force of an earthquake can push massive amounts of water called a tsunami toward a distant shore: "a tsunami can generate a particular type of wave called edge waves that travel back-and forth, parallel to shore. These effects result in many arrivals of the tsunami at a particular point on the coast" ("Life of").

        With enough initial energy and shorelines that may not have been extremely far away, the "edge waves" could have traveled back and forth over the newly submerged island and turned the surface to sediment. This wave action could have conceivably caused enough dirt and sediment to mix with the water so that when it all settled back onto the surface of the submerged land it would have been a "shoal of mud" (Plato) as described by Critias.

        The existence of Atlantis has been a cause for debate for a very long time. I don’t know if the question of whether Atlantis was real or not will ever be answered, but the question of whether it is possible for an entire island to disappear has been answered. It is physically possible for an entire island to sink below the surface of the water: In fact, many islands of volcanic origin are very slowly collapsing back into themselves at this very moment.