Saturday, July 19, 2008

The Reality of Plate Tectonics

Instructors at an NSF Oceanography Institute I attended in the mid-1960s were still using the term “continental drift” to describe the apparent movement of continents with respect to one another. The process was described for our class members, but not explained. Shortly after that, researchers showed that the ocean floor was moving apart from long mid-ocean rifts, a process dubbed “sea floor spreading.” Before that decade was over, the theory of “plate tectonics” provided an explanation. They gained an understanding of how the process works. In 1968, Canadian geophysicist and tectonics theorist J. Tuzo Wilson said, “The earth, instead of appearing as an inert statue, is a living, mobile thing.” Some science historians place the unfolding of our understanding of plate tectonics on a par with unlocking the genetic code, also an achievement of the 1960s.

Flashbacks from your general science classes may occur as you recall what you learned about the structure of the earth from center to surface: inner core, outer core, mantle, crust. The crust is sectioned into major and minor plates which fit together like a puzzle. The crustal plates “float” on the upper mantle, lighter rock on denser rock. Huge convection currents in the upper mantle slowly drag the plates. What is the result? Some plates converge, some diverge, and some slide past each other, all with results of significant impact.

Scientists of that era showed quite conclusively that the solid mantle does, indeed, slowly flow in convection currents on the order of a few centimeters per year. The long term effect, however, is measured in thousands of miles and in events of immense importance to human life. When first proposed, the theory of plate tectonics received its share of mockery and scorn. How could solid rock flow like a liquid? How could entire continents be moving around? This is reminiscent of the incredulous questions asked of Galileo: How could our earth be rotating when it appears we are stationary with all the heavenly bodies traveling around us?

No single, incredible process in nature offers final proof of design by an intelligent agent. Plate tectonics is but one of multiple processes which inspire our intuitive reflection about the design of the universe and its many functional “living, mobile” things. Courtroom juries look for “preponderance of evidence” supporting a verdict. This standard, while not proof beyond any reasonable doubt, certainly moves us closer to a verdict on supernatural design.