Tectonic plate boundaries are solid plates of lithosphere that cover the earth, and slowly move, causing different types of motion that affect the planet in different ways. Three types of movement are divergent, convergent, and transform. Each move in a different way, have different effects, change the topography of the planet in unique ways. Divergent plates move in a spreading motion, which affects the planet constructively by creating oceanic lithosphere, forming a ridge and is usually associated with volcanic activity. Convergent plates move through seduction, which means that one plate moves under the other, creating a trench. Volcanic activity is usually associated with this type of plate movement. Convergent plate movement is a destructive force that destroys oceanic lithosphere. Some evidence of this can be viewed in rock strata from ancient oceanic convergent activity, especially on Interstate 5, near the California and Oregon border, on the Siskiyou Pass, where rock strata are vertical instead of horizontal. In California, along the San Andreas Fault, the evidence of transformative plate movement is evident by the misaligned topsoil. Transformative plate movement slides laterally, and is considered to be conservative, as it does not destroy lithosphere, it slides, instead (Plate Tectonics: Plate Boundaries.,2010). There is to major disturbance in topography, and there is no evidence of volcanic activity, however there are earthquakes within the crust that cause major damage to human property. One other topographical plate feature is known as a hotspot. This is generally where volcanic action occurs frequently, such as the formation of the Hawaiian Islands through volcanic activity. No major earthquakes are associated with the volcanic eruptions, as they are constantly spilling molten rock, like thick, hot mud, which forms new crust (Your World is Erupting, n.d.).
One long glance at a map or globe that shows the ocean floor ridges, mountain ranges, and plate boundaries, it is easy to imagine the earth as one giant finished three dimensional puzzle, however the puzzle isn”t finished, as the divergent, convergent, and transform boundaries are always moving. Sometimes this movement is subtle and hardly felt by most organisms but can be recorded using special equipment that is sensitive to any movement of the crust. Sometimes the movement is strong enough to cause major damage to life near the movement. This movement is commonly called and earthquake. Earthquakes are most common along transformative boundaries or faults. In 1989, an earthquake in San Francisco measured 6.9 on the Richter scale. The damage caused 67 human deaths, and destruction of billions of dollars in property. However, another earthquake of the same magnitude that same year caused even more damage in Armenia. Structures that collapsed were not built to withstand such force. The death toll was estimated at over 30,000 people in that natural disaster. Earthquakes rarely have significant warning signs that would allow people to prepare adequately. Volcanoes have small to medium lithospheric tremors that give some advance warning of eventual eruption, and cause less deaths than earthquakes (Your World is Erupting, n.d.).
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"The Creation of the Ocean Floor".
The theory of continental drift is not difficult to imagine, as mentioned above, the contents are on tectonic plates that are continuously moving. The theory is that a very long time ago, estimated about 225 million years ago, all of the continents were one large landmass that scientists call Pangaea. Because of tectonic plate movement, the land masses began to move apart as new land was created and pushed apart (Plate Tectonics: Plate Boundaries.,2010). Looking at a map of the globe as it is now, it is possible to fit all the continents into one picture of what Pangaea may have looked like. The theory does have merit, as evidence of similar animals that live on different continents have the same basic genetic codes, such as African and Asian elephants. The facts are that no one was around back then to record the historical events from 225 million years ago, so speculation based on scientific study is the most effective resource available (Plate Tectonics: Plate Boundaries., 2010). Tectonic plate movement does prove that the contents are moving, as evidenced by the topographic nature of the ocean floors. The term continental drift is misleading, however, because the plates are not drifting like a floating mass on an ocean of magma. Instead, a recycling process of old tropospheric mass destruction in convergent plate movement, new tropospheric mass through the process of divergent tectonic plate movement, and a bit of transformative sliding is slowly moving the plates around to continue the cycle. Both theories have merit and could work together as one complete theory that could be called continental drifting of tectonic plate movement, which actually summarizes what is really occurring (Your World is Erupting, n.d.).
The Pacific Ring of Fire is a series of volcanic activity, colliding plates, and earthquake activity surrounding the Pacific Ocean. As the Pacific Continental Plate dives under the lithosphere, magma is generated through heat. This causes a trench in the ocean floor, and a vent through cracks in rock of a mountain. The vent is where the smoke, steam, and hot ash erupt before magma is pushed through the top, and sometimes through sides of the mountain (Plate Tectonics: Plate Boundaries., 2010). The downward plate is always oceanic because it is heavier, soaked with ocean water and saturated sediments. This is where most of the steam comes from as a volcano erupts, some of the steam is caused by magma heating ground water, and water soaked rocks in the mountain. The overlying plate will erupt, and the result is more landmass, if it is on a continent, such as the Cascade Mountain Range, which is a chain of mostly dormant volcanoes. If the volcano is in the ocean, it may create an island, such as the Hawaiian Islands which are still growing (Your World is Erupting, n.d.).
Whichever theory an individual decides to connect with, one thing will not change. The tectonic plates are moving, growing, changing, and most of it happens under the ocean floor. The Pacific Ring of Fire will continue to have volcanic eruptions and earthquakes as long as the plates continue to fold, push against each other, and slide against each other. Scientists will continue to study the moving planet as it evolves. As technology improves, the study of plate tectonics will change, and perhaps future generations will know much more about the subject than is available now.
- Plate Tectonics : Plate Boundaries. (2010). Plate Tectonics : Plate Boundaries. Retrieved from http://www.platetectonics.com/book/page_5.asp
- Your World is Erupting. (n.d.). Volcano World. Your World Is Erupting. Retrieved from http://volcano.oregonstate.edu/
