08.09 The Evolution of Plate Tectonics - by Terry Wright, Ph.D.

Geologist Terry Wright spoke to the Science Buzz Cafe Thursday night to a packed house. His stimulating talk was about the evolution of plate tectonic theory, a recent development in our understanding of how mountains form, how the continents got to be where they are and What's With All These Earthquakes. It was not until 1969 that geologists, including most of the curmudgeons and holdouts, came to agree with the modern understanding of just how dynamic the earth is. People had long noticed that the coastlines of Europe and North America, as well as the coasts of Africa and South America looked like they had once been jammed together. "Just coincidence", exclaimed the skeptics. Where is the evidence and where is the mechanism to drive whole continents around like leaves in a pond?

But as modern science and technology permitted new instrument techniques such as the surveying of the bottoms of oceans (which revealed massive undersea mountain ranges traversing the whole planet), heat measurements of the ocean bottoms (which showed massive heat flowing from the sea bottom mountains) and symmetrical magnetic stripes running in bands parallel to the ocean mountains, was the whole outrageous picture finally accepted. The mid-ocean ridges were hot spots where lava was continually oozing from the bowels of the earth, pushing outward to form new sea bottom, and "memorizing" the prevailing magnetic field of the time, which is known to occasionally reverse north and south poles. Where does the other entire ocean floor disappear? Massive plates crash into other massive plates causing one to slide under the other, pushing up mountain ranges and treating us on the left coast to earthquakes as the plates bump and grind and shimmy. It is all very sexy.

Not to be satisfied with mere sex, Terry then illustrated the mechanics of the process with - candy bars and Oreo cookies. Oddly, no one smoked afterwards, although a spot of cabernet he provided was a welcome touch.