Plate Tectonics

Plate Techtonics

Table of Contents

Introduction 02

Chapter 1. Plate Tectonics: Pangea to present. 03

Chapter 2. Plate Tectonics: Possibilities 09

Chapter 3. Conclusion and Discussion 10

Bibliography 11

Plate Tectonics

Introduction

From the time we are of an age of understanding, many of us are taught (or made to learn) the basics of creation, the teachings of the bible as a guide and precept for life, and the ultimate belief in a Supreme Being, or God. When Charles Darwin initiated the first doubts into the minds of Western Civilization that humans may have been descendant from apes, a virtual monkey wrench was thrown into these basic beliefs which had permeated our reasoning since our dawn of time. The blasphemous thoughts that a being created in the image of God could be so descended from a so-called, "Missing link," was unthinkable. It created chaos into the biblical beliefs of creationism and the existence of God. From the earliest mappings of the earth's surface, a thought eventually emerged regarding the possibility that there may have been one mass continent, or a series of connecting links or bridges. This was perceived by the remarkable possibility that the eastern coast of South America and the western coast of Africa appeared to have been cut and separated. This gave rise, in the 19th century, to expeditions to prove this theory. These expeditions and discoveries gave us plant and fossil proof of lands once connected through common locations in probable connecting points. It was through the works and writings of Seuss, Taylor, and Wegener that paved the way for the eventual concept of Plate Tectonics in the 1960's. Ancient Hawaiians may have perceived land movement in their own primitive stories of two super beings, or gods, to explain their reasoning. They realized early in their history that the volcanoes to the north were dead or dormant with active volcanic life in the south. It would be many centuries later that the existence of "Hot Spots" would explain their existence and the tectonic plates which contain these islands. The concept of plate tectonics brings to light the realization of a living and evolving earth which has the powerful ability to change one's views on the origin of man, and question the concept regarding the true existence of God. It is not my contention to prove or disprove the existence of a Supreme Being, only to provide a basic understanding of plate movements and their possible affects on human life. If that were my true contention, then the belief or theory of the land of "Pangaea," approximately 225-million years ago removes the concept of the existence or creation of the "Garden of

Eden," or our first parents, "Adam and Eve," in 4004 B.C., which biblically coincides with the time of, "Let there be light."

Chapter One

Plate Tectonics: Pangaea to Present

In mid-1978, an earthquake on the Tijuana-San Diego border lasting approximately 33 seconds bounced me around the room on my bed. For me, it was the first earthquake of my experience and my most exciting. Since that one, I have been present and witnessed as many as 35 earthquakes in California, and even took part as a member of the cleanup and aerial survey of powerlines and dams. Unlike the tornadoes of Texas and the region known as Tornado Alley, earthquakes strike without warning and their destruction is as traumatic and devastating as a tornado. The difference is people receive tornado warnings, nobody in the world receives earthquake warnings. As a boy growing up, I remember being told that earthquakes were caused by companies drilling for oil, water, or other minerals leaving voids in the earth resulting in cave-ins of mass proportions. During this same time period of the 1960's, the theory of plate tectonics was making its entrance on the evolutionary stage. The theory of plate boundaries and continental drift aren't as new as may seem. A map drawn by a French geographer, Antonio Snider-Pelligrini, as illustrated in the picture below, indicates that the concept of continental placement was not new as early as 1596 when first postulated by a Dutchmannamed Abraham Ortelius.

Pellegrini's map was produced in 1858. It would be approximately 57 more years before Albert Wegener would produce his own depiction of pre-seperation earth with his belief in a supercontinent he named Pangaea, meaning "all land" from the Greek.

Yet Wegener was not the only geologist to also consider a single continent concept as is learned from the writings of Edward Seuss. It was Seuss who compared discoveries of plant and animal fossils in India, South America, South Africa, and Australia to build on the idea of a common land mass in pre-historic times. The discovery of the Mid-Atlantic ridge in the late 1800's made way for a thought to be introduced by author Frank Taylor that the aforementioned ancient continents seperated and formed the now familiar Atlantic Ocean. When Albert Wegener introduced his book, "The Origin of Continents and Oceans," in 1915 he introduced the theory of "Continental Drift" from a single continent. His idea led to a similar reception, albeit nicer, than did Darwin's when he hypothesizes the belief that man was decendant from another primate; relating man to apes. However, the writings of Wegener and Seuss both compared specimens from various continents as illustrated in the insert on the next page

showing fossil and plant commonalities to other regions. This information, coupled with the jigsaw puzzle fit of the eastern coast of South America and the western coast of Africa, led to more discoveries. Notice that the GlosseropterisPlant is common to five areas; the Cynognathus, Mesosaurus and Lystrosaurus are also common to lands which today are independent continents.

With the information provided, it is plain to see that the earth is a planet which is a constantly changing entity, a dynamic mechanism always in motion through the principle of Plate Tectonics. Another clue to the dynamic motion of the planet is the presence of "Hot Spots," located in multiple locations around the planet. The most famous is the hot spot beneath the Hawaiian Islands in the Pacific Ocean. As shown in the following illustration, a timeline of volcanic activity can be determined. Notice the northern most island of Kauai was active approximately 5 million years ago, followed by Oahu, Molokai, Maui and the big island of Hawaii.

As time passes and the plates continue their move northward, Kilauea will eventually become dormant followed by another island approximately 500 thousand to 600 thousand years later. As shown below, the hot spot which had made or created the Hawaiian Islands has been producing islands at least 58 millions years as shown in the following illustration. Notice the Hawaiian Island chain includes the Midway Island chain and the Emperor seamounts.

Can it be determined from this that the seamounts north of Midway were once islands containing life prior to being weathered down and now existing below the ocean waters? The theory of plate tectonics set in motion many more questions, one of which could have been, "Okay, we have the idea of what happens, now let's figure out how it happens." Which takes us back to the Mid-Atantic ridge. Tests done proved a hypothesis that if the Mid-Atlantic Ridge produced new rock, then the rock should be getting older as we move from it. And this proved true in each direction, east and west from the ridge. As illustrated on the following page, magma has been hypothesized as reacting similar to water boiling, this action thus believed to cause the crust to act in a reactive manner.

It is said, that with every question conceived, ten more questions are generated. And so, if the aforementioned questions were perceived as true, how can they be further proven. In comes satellite photography. As depicted from the following illustration, concentrating on the Mid-Atlantic Ridge, we note that the land masses are growing further apart.

As is evident, the crust is more aggressive in the southern hemisphere than in the northern, comparing 4.1centimeters in the south to 1.8 centimeters per year in the north. As is very noticeable, plates are either moving away from each other, called "extensional," or "divergent." Others are moving towards each other, called "compressional," or "convergent," and finally "tranformal," because they move parallel to each other in opposing directions. This is the situation from California into Mexico. As the land masses move parallel to each other, eventually stress points meet. The sudden release of pressure causes a violent, rapid movement resulting in shockwaves radiating away from it. These shockwaves produce the earthquakes similar to the one which bounced me around the room, that destroyed the Northridge area of Los Angeles and leveled Mexico City. The transformal fault line, called the "San Andreas Fault Line," has a parallel movement of approximately 5.5 centimeters per year.

Courtesy USGS

Compressional lines form subduction zones, whereby the ocean crust flows towards the land mass. The land mass in turn is flowing towards the ocean crust. The ocean crust is forced down below the land mass which becomes heated causing mountain ranges to be developed.

Chapter Two

Plate Tectonics: Possibilities

As plate tectonic activity continues to change the face of the planet, some activities being very noticeable and profound in its change, are we to see new developments to prove some unanswered hypothesis? As is evident on the African continent, will the Eastern Rift separate at the Gulf of Aden? Will we see a new island form in our lifetime, similar in magnitude to the events which have taken place in Iceland? The divergent zone making up the Eastern Rift in Africa is separating at a pace of perhaps 2.0 centimeters per year. The rift

zones containing the Red Sea and the Gulf of Aden began in very much the same way. As the rift widened, water began to flow in forming large bodies of water. As is apparent in aerial photographs and artists depictions, these rift zones may produce a new island off the coast of East Africa. Could the island of Madagascar have begun the same way? The two hot spots on the north and south ends of Iceland are recent occurrences which have changed a way of life for the people inhabiting the villages near the volcanoes there. Similar to the volcano on the big island of Hawaii, an entire village disappeared under the lava flow, leaving a single palm tree and a piece of asphalt road as a lonely reminder that life once existed in that charred landscape. Not mentioned in the previous chapter is the changing face of the earth as polarity in the magnetic field changes. What effect will this have on the carbon based life-forms currently existing on the planet? Since most polarity changes continue into the millions of years, could this explain why some species have become extinct over the years? The current polarity being the longest recorded in 4.5 million years, are we due for a polarity change in the near future? If so, how will this affect humanity? Perhaps mankind and other living creatures will enter a metamorphic change as the polarity changes.

Chapter Three

Conclusion and Discussion

As illustrated in the following depiction, the region known today as the Magnetic North Pole has characteristics as explained in the theory of Plate Tectonics. The Cambrian period began 505 million years ago followed by the Devonian period 360 million years ago. As the pole

progressed to it's current position in the northern hemisphere, land masses also relocated to their current locations. In 2003, the Magnetic North Pole was located at 82.0 degrees North Latitude, 112.4 degrees West Longitude; for 2004, it is at 82.3 degrees North Latitude, 113.4 Degrees West Longitude, and projected to be at 82.7 degees North Latitude, 114.4 degrees West Longitude in the year 2005, per the Canadian Geologic Survey.A distance travelled of approximately 19.8 miles for 2003-2004, and an additional 25.2 miles for 2004-2005.

Considering this, and the movements of the plate boundaries, the Atlantic Ocean is becoming wider at a rapid pace in geologic time, per se. As this occurs, will this cause the Pacific Ocean to become narrower? If this is a truth, then in about another half-billion years, will a single land mass again form? This time, on the opposite side of the globe? This was a hypothesis proposed by a Canadian Geologist, J. Tuzo Wilson in the early 1970's. Indirectly and directly, plate tectonics, or plate movements, affect our lives on several fronts. The fault lines interacting cause earthquakes. Open fissures and calderas allow hot magmatic exhausts to escape, changing the surrounding landscapes. The airborne particles cause changes in the weather systems, and depending on the amount of thrust from the volcano or caldera, destroys ozone. Land mass features change with the plate movements and, plant and animal life metamorph with the changes over time, some ending in extinction. The earth is a living entity containing life...as it changes, so does all other life which is dependent on it for existence. Different forms of

life have had their periods of rule over the planet from micro-organisms, to plants, dinosaurs and now humans. It would be interesting to know what's next.

Bibliography

1. The Changing Earth, Exploring Geology and Evolution, 3rd Edition, Chapter Nine

2. United States Geologic Survey, "This Dynamic Earth"

3. "All about Plate Tectonics: Earth's Plates and Continental Drift" ( http://www.enchantedlearning.com/subjects/astronomy/planets/earth/Continents.shtml )

4. "Class Notes and Guidelines" by Professor Akiwumi, Geology Department, Hill College Hillsboro, Texas

5. The Magnetic North Pole, Canadian Geologic Survey