4: Plate Tectonics
- Page ID
- 20338
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- Describe the geological processes that take place at divergent, convergent, and transform plate boundaries.
- Describe the physical mechanisms that drive plate movement.
- Locate and describe California’s major plate boundaries.
Introduction
Plate tectonics is a theory that best explains all available observations concerning the Earth's geological features and their changes over time. As a theory it is constantly being evaluated and refined. More specifically, it is a model that explains the origins of continents and oceans, folded rocks and mountain ranges, igneous and metamorphic rocks, earthquakes and volcanoes, and the movements of the continents. Plate tectonics was first proposed in 1915, but did not become an accepted part of geology until 1965. It took 50 years for this theory to be accepted for a few reasons.
First, plate tectonics was a paradigm shift in thinking about Earth and it was difficult for many established geologists to accept. While observations made by Alfred Wegener concerning the movement of continents were complete and his hypothesis of ‘drifting continents’ was very astute, he could not explain a driving mechanism that would account for the perceived motion of the continents through time. Many geoscientists would not accept his ideas without an explanation of a plausible driving mechanism.
Second, many of Wegener’s observations were from studies of rocks, fossils and landforms in the southern hemisphere and most geologists of the time were in the northern hemisphere (Europe and North America). These Northern Hemisphere geologists were unfamiliar with the rocks and structures in the southern hemisphere. It was difficult for them to independently verify Wegener’s observations and therefore easier to discount them.
Third, the technology necessary to collect the data to develop the concept of plate tectonics simply did not exist until the middle of the 20th century. Though not covered in depth in this resource, we recommend exploring the development of Plate Tectonics theory in Physical Geology – H5P Edition (Panchuk, 2021).