An Understanding of Plate Tectonics

One of the most interesting aspects of Geology and Earth Science is the tectonic plates. Pieces of the Earth’s crust floating atop the bubbling, hot mantle, have the capability of causing earthquakes, tsunamis, deep ocean valleys and towering mountains. This article will explain the basics of tectonic plates while also sharing a lesser-known part of history: female cartographer Marie Tharp’s and Alfred Wegener’s story. 

Marie Tharp’s interest in map making was sparked by her father, a surveyor for the US Department of Agriculture, exposing Tharp to various skills that would prove to be useful later on in her career. Tharp initially graduated with a degree in Music and English. However, World War II created new opportunities for women in higher education, as universities sought to fill classrooms (“About Marie Tharp | Lamont-Doherty Earth Observatory”) .

 Tharp ended up attending a petroleum geology course, earning her masters in the field. She worked for an oil company but was confined to office work while her male counterparts were given the opportunity to do fieldwork as a result she moved to New York to collaborate with Bruce Heezen at Columbia University to map the ocean floor. While Heezen spent time aboard boats, Tharp painstakingly used sonar readings to create the textured profile of the undersea floor, particularly the discovery of the Mid-Atlantic Ridge. Her final published data was controversial as it proved a theory that continents could gradually move, also proving the idea of seafloor spreading. Tharp’s ideas were finally accepted by the scientific community, forming much of what we learned in primary school about the Earth(“About Marie Tharp | Lamont-Doherty Earth Observatory”). 

Alfred Wegener was a German geologist popular for his continental drift theory. Continental Drift focuses on the idea that the Earth's large land masses could fit together like a jigsaw puzzle. 

The shape of the American continent aligns with that of the African continent. Wegener noticed after analysis of fossils and geological structures on both sides of the Atlantic, that there was a match in fossil plants and many similarities (The Editors of Encyclopaedia Britannica). From 1912 to 1915, he became a firm advocate for his ideas, predicting the giant continent of Pangaea which we learn today while also speculating about seafloor spreading creating mid-ocean ridges. His ideas were finally proven by Tharp and Heezen’s discovery of the Mid-Atlantic Ridge; however, Wegener passed away after an expedition in the Arctic, unable to see the true impact of his scientific revolution (The Editors of Encyclopaedia Britannica). 

Source: NOAA

Now, what exactly are tectonic plates, and how do they shape our world?

In all actuality, plate tectonics is still a theory that explains mountain building, volcanoes, and earthquakes in our lithosphere. The Earth can be divided into many different layers such as the crust, lithosphere (crust and uppermost mantle), asthenosphere (upper mantle directly belowthe lithosphere), lower mantle, outer core and inner core.

Convection currents in the Earth’s mantle move the pieces of the crust. Just like how different pieces fit differently in a puzzle, there are different boundaries on which plates move along. One such example is divergent boundaries where two tectonic plates move away from each other, exposing Earth’s mantle, which bubbles to the surface and solidifies (Ocean Exploration). In real life, this is seen by the Mid-Atlantic Ridge and creates new oceanic crusts. Another example is when two plates collide at a convergent boundary (Ocean Exploration). Both plates may buckle against the force and, like pressing two palms together, cause a mountain to slowly be formed over thousands of years (Ocean Exploration). One plate might yield under the pressure and slide under, forcing it under the mantle to melt. The melted mantle may be squeezed up into volcano formations which parallel the plate boundaries (Ocean Exploration). An example of this is the Pacific Ring of Fire, where earthquakes and volcanic activity are common.

Lastly, there is a transform plate boundary where two plates slide along each other, creating faults in the crust, and parts of the tectonic plate are crushed. This motion creates frequent earthquakes, but no new crust is made from the mantle emerging.

Living in the Ring of Fire, I experience frequent earthquakes, though most are minor. 

 It is important to educate people about disaster relief and disaster preparation in case the country experiences a devastating earthquake. More specifically, I live near a dormant volcano; the area around is very fertile with many farms and the community can derive benefits from the geothermal activity such as hot springs and also sulfur deposits. 

Earlier in the article it was mentioned that tectonic plates can cause tsunamis; this occurs at the subduction zone as the plate slips under but gets stuck, pressure slowly builds causing the overriding plate to deform under the stress; over time this builds up and if there is an earthquake and the plates suddenly move, the overriding plate can buckle, displacing the water above it and causing a huge wave. (NOAA) Generally, only earthquakes larger than an 8 magnitude tend to cause this kind of event. Notable but tragic examples include the 2008 Indian Ocean Tsunami and the 2011 Fukushima Daiichi Disaster. 

Overall, plate tectonics is a fascinating way to understand the moving world beneath our feet and how large changes to our planet can happen instantly but also over millions of years. Imagine what the world would look like 1000 years from now. 

References

“About Marie Tharp | Lamont-Doherty Earth Observatory.” Columbia.edu, 2012, marietharp.ldeo.columbia.edu/about-marie-tharp. Accessed 20 Mar. 2024.

AMNH. “Plates on the Move | AMNH.” American Museum of Natural History, 2012, www.amnh.org/explore/ology/earth/plates-on-the-move2. Accessed 12 Mar. 2024.

Earthquake Science Center. “Tectonic Plates of the Earth.” Www.usgs.gov, www.usgs.gov/media/images/tectonic-plates-earth.

NOAA. “Tsunami Generation: Earthquakes.” Www.noaa.gov, 27 Sept. 2023, www.noaa.gov/jetstream/tsunamis/tsunami-generation-earthquakes. Accessed 11 Mar. 2024.

Ocean Exploration. “What Are the Different Types of Plate Tectonic Boundaries?” Noaa.gov, Ocean Exploration, 2010, oceanexplorer.noaa.gov/facts/plate-boundaries.html. Accessed 12 Mar. 2024.

“Plate Tectonics - Island Arcs.” Encyclopædia Britannica, 2019, www.britannica.com/science/plate-tectonics/Island-arcs. Accessed 12 Mar. 2024.

“Plate Tectonics Guide for KS3 Geography Students.” BBC Bitesize, www.bbc.co.uk/bitesize/articles/zrcgr2p#z8b48hv. Accessed 12 Mar. 2024.

The Editors of Encyclopaedia Britannica. “Alfred Wegener | Biography, Theory, & Facts.” Encyclopædia Britannica, 2019, www.britannica.com/biography/Alfred-Wegener. Accessed 12 Mar. 2025.

University of California Museum of Paleontology. “Alfred Wegener.” Berkeley.edu, 2019, ucmp.berkeley.edu/history/wegener.html. Accessed 12 Mar. 2024.