Tectonic Plate Boundaries, Their Movements, and What Happens to the Earth Around Them
What does a breakfast diner and the Earth have in common? They both rely heavily on plates. The crust of the Earth is ruled by the movements of tectonic plates, meaning they move and shift. They are contained in what is called the lithosphere. National Geographic magazine (2014) teaches, “The movement of the plates creates three types of tectonic boundaries.” They are named; convergent boundaries, divergent boundaries and transform plate boundaries. Additionally, “most geologic activity stems from the interlay of where the plates meet or divide and move at a rate of one to two inches per year.” I will explain these differences, give an example of where these plates meet, and what happens to the surrounding shifting Earth.
The first type is a divergent boundary. These plates pull away from each other afterward magma rises to form new crust. This is a process very few get to witness because most divergent boundaries are on the ocean floors like the Mariana Trench. According to my World Book Encyclopedia, “This process creates about 1 square mile (2.4 square kilometers) of ocean crust a year.” Furthermore, the African Rift is our primary example above ground. In the Olduvai Gorge area, many exciting discoveries were made by Donald Johansson and the Leaky family. You have probably heard of Lucy, which is believed to be an early ancestor to hominids. The Leaky family found even earlier fossils which are called Australopithecus Robustus. The gorge was in a way a time capsule(Haviland, ). In sum, these discoveries were breakthroughs for the scientific community. Which isn’t as interesting as my next point.
Convergent plate boundaries are by far the busiest and have multiple examples. Firstly, it would be the Himalayas. When landmasses on the plates collide, they buckle making mountain systems. This is called continental-continental convergence. Geologists estimate that this occurred around 55 million years ago when India and Asia came together. Next, there are places called subduction zones. Think of a big plate sliding over one another, while the bottom plate is getting recycled into the mantle creating deep ocean trenches. In some areas instead of mountains, deep ocean trenches are formed. Finally, these subduction zones can generate powerful earthquakes and often form a chain of volcanoes on the overriding plate building up until islands such as Japan, Java, or Hawaii exists (USGS, 4). This is called an Oceanic-continental convergence which makes up what is aptly named the Ring of Fire.
The final type transform plate boundaries neither collide nor do they pull apart. They merely slide past one another horizontally. The Bear state California has a perfect example involving the San Andres Fault, where the North American Plate meets the Pacific Plate. This fault is connected to a ridge that runs the span starting at the Gulf of California to a trench off the Northern California coastline. It’s a spectacular sight in the late afternoon but my advice is to wear good boots or shoes when visiting. Hiking here is one of my favorite memories of when I was a teenager going on vacation with my mom and dad. In the 1990s there were hiking trails maintained in several sections of the fault; although, I cannot vouch for them being there today. Since this section of land is on the Pacific Plate it is not a question of if California will separate from the continental U.S. but when? The changes will be slow; however, earthquake activity dictates how quickly the plates will move.
When one considers what happens to the Earth in these places, it’s clear that there are differences between divergent, convergent and transform plate boundaries. Therefore, we humans must adapt to the changing geography without changing a cycle that has been in play since before the early hominids or risk disrupting this delicate balance. It will be exciting to see new islands and mountains be formed albeit slowly. Mother Earth is far from finished sculpting her masterpiece leaving scientists as well as tourists in awe of the world we live in. What secrets will humans uncover in our insatiable curiosity as time passes? What tragedies might occur? Only time and our willingness to adapt will foretell the outcome.
Works Cited
Cloos, Mark. “Plate Tectonics.” The World Book Encyclopedia. 2007 ed. 2007.
Hiviland, William A., Herald E.L. Prins, Dana Walrath, & Bunny McBride. Anthropology: The Human challenge. 14th ed. Belmont, CA: Wadsworth Centage Learning. 2014.
National Geographic. “Science Reference: Plate Tectonics.” National Geographic Society, 2019. web,.
17 November 2019. <https://www.nationalgeographic.com/science/earth/the-dynamic-earth/plate-tectonics/>;
USGS. “Understanding plate motions.” usgs.gov 15 Aug 2014. Web,. 17 November 2017. <Https://pubs.usgs.gov/publications/text/understanding.html>;
written in November 2019 in EH101 as a Classification Essay