Plate tectonics: A deep time and planetary perspective John
Weber, Geology Department, Grand Valley State University James
Lawrence Powell, in his poignant and insightful popular science
book, Mysteries of Terra Firma, lists and discusses the three
big ideas (paradigms) in Earth science: time (age of the Earth),
drift (plate tectonics), and chance (impact). Perhaps a fourth,
ice ages and global climate change, could be added. Much to our
surprise, and after much exploration and expectation – e.g., we
had expected to find evidence for plate tectonics on Venus, – it
turns out that Earth is the only planet in the solar system on
which plate tectonics occurs, today. Some interesting questions
arise: When did plate tectonics get started on planet Earth, and
how long has it been operating? If not always plate tectonics,
what other kinds of tectonics operated on Earth? Why do all of
the other terrestrial planets have single-plates and what has
been called "stagnant lid" tectonics? Could these neighbors have
had plat