The Get Real! Science team grappled with the first question in the past week, learning that there are more than a few ways to define this subject that forms the basis of our work as science educators. The National Science Education Standards from the National Research Council (1996) describe science as “a way of coming to understand the world in which we live”. Chiappetta & Koballa (2010) carry this description further by pointing out science’s distinction from other knowing disciplines because “it has standards and practices that generate ideas to explain phenomena and to predict outcomes”.
Now that we better understand what science is, what is geoscience? Geoscience is the multidisciplinary and interdisciplinary study of Earth, including its atmosphere and oceans. A recent article in a geoscience journal depicts a problem long studied in the geosciences: the Earth’s crustal thickness. This is a model showing the principal layers of Earth, and as you can see, the crust is the thin layer on the surface, underlain by the mantle and core.
Image: Ed Garnero, Arizona State University. Simple Earth.
We live on Earth’s crust! Knowing the thickness of the crust is useful for a great many geoscience observations such as the location of mountain belts and ocean depths, geohazards, and also for natural resource exploration and management (Alvey et al., 2018).
Yin + Yangster by Laura Yang. Earth’s Crust.
Over many decades of research, there have been numerous interpretations of crustal thickness on Earth. With progress in the geoscience epistemology and new and improved technology, geoscientists are getting closer to making more accurate characterizations of the global distribution of crustal thickness. The map below depicts crustal thickness for both the continents and oceans as derived from gravity studies. The shaded relief represents the gravity anomalies and note how the tectonic features are revealed (Alvey et al., 2018). What are gravity anomalies? How can gravity anomalies tell us about crustal thickness? What is the rough average thickness for continental crust? How about oceanic crust? Next time, I will go over Earth modeling and how geoscientists use models, such as the one below, to represent phenomena.
From Alvey et al. (2018). Global map of crustal thickness derived by gravity inversion (OCTek). The Gulf of Mexico and Indian Ocean regions are in the boxed areas. Note the very thick crust of the Tibetan Plateau and the very thin crust in the ocean basins.
This is part of the East African Rift System in Djibouti, Africa. Rift zones are associated with areas of thin crust. Can you find any of these zones in the global map above?
The crustal thickness study is an important part of the geoscience field of tectonics. There is a long and fascinating history of plate tectonics! Shown below is Alfred Wegener, a German meteorologist who is considered to be the “Father of plate tectonics” after his 1912 hypothesis that at one time the continents were joined into a “supercontinent” called Pangaea which broke apart and drifted away about 200 million years ago. He deduced this from observations of fossil and rock formation similarities between the continents where their coastlines matched. This hypothesis was vexing to most geoscientists of the day who believed the continents were not able to move laterally. Wegener faced rejection and even ostracization from many of his colleagues and, sadly, he was never to know his theory of continental drift led to the acceptance of plate tectonic theory in the mid-1960s and its revolutionary influence upon geoscience.
Alfred Lothar Wegener—never to know he would become the “Father of plate tectonics”. But his haute couture and pipe might have been enough for him! Photo by Mary Evans Picture Library.
As this week’s class blogger, Alyssa, mentions, we had a most interesting visit from a professor of Environmental Conservation and Horticulture at Finger Lakes Community College: Dr. John VanNiel. Dr. VanNiel demonstrated a creative way of teaching us about our New York fauna by building on what we knew (or thought we knew) and steering us from observation to inferences toward what is known (or thought to be known); for scientific knowledge is always “tentative” (Chiappetta & Koballa, 2010). As budding educators, we are learning how to teach science (next week’s blog topic!) and Dr. VanNiel’s approach to engage of all of us in science inquiry methods made for a memorable and fun class. He helped us to find our own way to “understand the world in which we live” (National Research Council, 1996)
Next week, our Get Real! Science team digs deeper into how one learns (geo)science. Until then, be sure to browse through my cohort’s blogs to examine their views on “What is Science?” this week too!
Below are some links to some of the preeminent geoscience organizations, have a look and see if you can answer the questions posed in this blog by next time! Peace out!
American Geosciences Institute: https://www.americangeosciences.org
The Geological Society of America: https://www.geosociety.org
American Geophysical Union: https://sites.agu.org
Alfred Lothar Wegener. Photo by Mary Evans Picture Library. Retrieved from https://fineartamerica.com/featured/alfred-lothar-wegener-german-mary-evans-picture-library.html
Alvey, A., Roberts, A., & Kusznir, N. (2018) What is the thickness of Earth’s crust? Geoscientist. 28(7), 10-15.
Chiappetta, E.L. & Koballa, T.R. (2010). The nature of science. In Science Instruction in the Middle and Secondary Schools, 100-108, Boston: Allyn & Bacon.
Ed Garnero, Arizona State University. Simple Earth. Retrieved from http://garnero.asu.edu/research_images/images_all.html
National Research Council. (1996). National Science Education Standards. Washington D.C.: National Academies Press.
Yin + Yangster by Laura Yang. Earth’s Crust. Retrieved from http://yangstercomics.com/life/earths-crust/