Researchers are stating that beliefs about the origin of western mountains in North America are all wrong.
In “Geologic History of North America Gets Overturned,” Live Science described how thorough the overturning was: “It’s time to redraw the map of the world during the reign of the dinosaurs, two scientists say.” The scientists, from Germany and Canada, dispute the existence of the Farallon Plate, long thought to give rise to the Rocky Mountains. Instead, they posit an archipelago, such as those in the South Pacific, instead of a continental margin. Finding stacked remnants is their justification for the overhaul. The new model is more complex in some ways, but also simpler, Nature News claimed in “How the West Was Built.”
[Mitchell] Mihalynuk said the new model will make waves, as it overturns 40 years of accepted wisdom about the evolution of western North America. “It will take a while to turn people around. That intellectual ship has a lot of inertia,” he said. But for Mihalynuk, “this is one of those eureka moments.“
If they are right, 40 years of accepted wisdom was really never wise at all. While this new model “makes perfect sense” to some, will it make sense to geologists 40 years from now? There’s room for reconsideration. The paper in Nature by Sigloch and Mihalynuk lists four areas of uncertainty and a fudge factor to make the model work: “This is accomplished by introducing an additional degree of freedom, an ad hoc, otherwise non-observable, westward shift of the lithospheric shell relative to the lower mantle.”
In a Perspective article in Nature, Saskia Goes said, “The tectonic history of western North America is a puzzle in which many of the pieces are mashed up or missing.” Although she believes the new seismic image data alters the reconstruction of the pieces, she described the observational data as complex: “The western margin of the North American continent, comprising the Cordilleran mountain chain that runs from Alaska to Mexico, consists of scores of continental jigsaw pieces of different origins, sizes and ages.”
Goes made it clear that the new model is not fixed in stone. “Sigloch and Mihalynuk have incorporated several new pieces into the North American jigsaw, but others remain to be placed,” she said. More modeling and interpretation will be required. “The new pieces remain to be connected into a self-consistent framework of plates with continuous and dynamically evolving boundaries,” she added, implying that the model is not self-consistent yet. Her piece ended with a number of remaining questions.
Nothing in historical geology is ever as clean cut as the popular media would lead you to believe. They give the impression of progress: the new model is superior to the old. Is it necessarily? When you are dealing with scores of “jigsaw pieces” without the box cover to show you what they are supposed to look like, and no human observer around to watch what really happened, there is ample room for another overturn in the future.
There is also ample room for alternative theories with different assumptions or different ad hoc, non-observable fudge factors. Some philosophers even claim an infinite number of theories can explain the same observations. However stated, theories and models like this are always “underdetermined” by data. It means that a measure of divination is required to conjure an appropriate vision that suits the preferences of the day.
Overhauls also remind us that the consensus is often wrong. Forty years of false belief is what these two upstart geologists have to allege by overturning the old model: forty years of “accepted wisdom” that was foolish in their view. The new accepted wisdom awaits future self-proclaimed wise men ready to upset the applecart all over again.
This is accomplished by introducing an additional degree of freedom, an ad hoc, otherwise non-observable, westward shift of the lithospheric shell relative to the lower mantle.