This is Part 8 of a series of approximately sixty posts that outline evidence, support, and explanation for naturalistic evolution. Receive updates and notification of all posts from dennismitton.com by selecting the follow button on the sidebar of any page. Thanks!
Pangaea and Plate Tectonics
It’s a jump to move from the philosophical basis of science to plate tectonics but it shows how uniformitarianism and not catastrophism best describes earth’s history. Later on, when I write about island evolution, I’ll show how tectonics have played an important role in plant and animal diversity.
It wasn’t lost on early cartographers that the shapes of the continents, when drawn out in a bird’s eye view, look very much like an exploded puzzle. Little imagination was needed to see how, with a tweak here and a shove there, that one could arrange the continents into one large land mass. As many times as this was written up or presented in scientific meetings, it was muffled. The earth was believed by Westerners to have been created just as it is with periodic episodes of immense geologic upheaval. It was clear that the earth changes: there were fossils, there were seashells found within mountains, and geologic formations were found around the world that were obviously topsy-turvy. But as the nineteenth century turned to the twentieth, the particular Biblical world view that God created everything as it is, must hold. And Really? If the land moved, if continents were once shoved together, why don’t we see movement? If the creation is only 6,000 years old, wouldn’t we see where continents had drifted?
But uniformitarianism was taking over science (See Part 7). The new science of geology was looking at rocks and formations and rivers through a new lens and developing scientific ideas based on observation and evidence. But the old ideas didn’t easily die and it took several decades of evidence for Cuvier’s books on catastrophism to become musty relics good only for propping doors open.
When we jump ahead a hundred years from Cuvier (Part 6) to the early twentieth century we see a different world. The call of uniformitarianism – the present is key to the past – has become the standard on which modern science is built. Darwin has published his books and scientific evolution has taken hold within biology. But there are gaps in our understanding. One persistent question was how similar organisms appeared on both shores of the Atlantic. Researchers and collectors noticed that certain plants and animals from both South America and Africa were strikingly similar and not found elsewhere. Explanations of trans-ocean voyages were unsatisfying. And then there is Australia. What happened there? Was God out drinking or was he just having a bit of fun?
Answers were still unsatisfying when meteorologist Alfred Wegener published The Origin of Continents and Oceans in 1915. In this book, he gathered evidence to argue that the shapes of the continents combined with plant and animal evidence clearly shows that the continents once made a single large landmass later named Pangaea. But Wegener couldn’t be sure of the means for movement and his idea, known as Continental Drift, was not fully embraced. Instead, he touched off a fifty year war within the walls of geology lecture halls between Drifters and Fixists. Drifters sided with Wegener regarding plate movement while Fixists argued that plates stayed in place without moving. Technology and the evidence it reveals was on the side of the Drifters. Over the next decades, geologists found oceanic crusts spreading open, studied how earthquakes are explained by convergent plates, and came to a better understanding of earth’s interior. Seismic and magnetic studies bolstered the case until the middle of the twentieth century when plate tectonics – the term used to better describe Continental Drift – became the defacto explanation for geologic activity.
How continents move is still a question. (See here for a brief video.) It is known is that the continental plates are thick heavy crusts that ride atop a much hotter and much more fluid and elastic substrate. The prevailing idea is that the earth’s mantle under the plates is extremely hot. This heat creates a convection pattern within the earth under the crusts. As the waves near the surface of the substrate, they are deflected and create a flow that pushes the crust along the flow like a leaf drifting downstream. How much do the plates move? Rates have changed and we know that different plates move at different speeds. Per the United States Geologic Survey, the Atlantic has been widening about an inch per year for millions of years. The Pacific Northwest Seismic Network reports that the Juan de Fuca plate off the West coast of Washington moves East Northeast at about four centimeters per year. Pretty fast but no need to sell the home quite yet.
Next we’ll talk about the good stuff: fossils.
Once you move out of the question of evolution proper you find that there aren’t as many detractors for the facts that are explained by evolution. Not many people or groups argue against plate tectonics or the hot core of the planet. These findings don’t bump up against ideas about who we are or where we came from. If that housewife in Georgia with a fish eating Darwin sticker on the back of her minivan knows what plate tectonics is, I can almost guarantee you that she doesn’t care.
But there was recently a geology dust up that got creationists pretty excited. A report was published that the Andes were pushed up in place very quickly in geologic time instead of over millions and millions of years as was previously expected (here). For the life of me, I don’t understand why creationist were excited: the speedy lift of the Andes was guessed at maybe 7-8 million years which still doesn’t fit in very well with the telling of Biblical creation but I think that anything contrary to the generally accepted story excites these folks, so deep is their fear of science.
The stir created by the original paper has generally calmed. Responding to the quick rise scenario, other researchers argue that evidence used for the quick-rise scenario was misinterpreted isotopic results of climate change. (Here)
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I really enjoy these Oxford shorts.