When we do, we find that Earth's topography is not normally distributed, which leads us to the important conclusion that continental crust and oceanic crust are fundamentally different from each other see my screencast explanation below. The realization that oceanic and continental crusts are different from each other was a huge leap towards figuring out sea-floor spreading and plate tectonics. If the contracting earth hypothesis were true then what you would expect is a random distribution of elevations at the surface.
In fact, the mean elevation on Earth is actually at about 2km below sea level. The real distribution looks like this. There are two peaks. One is near sea level, which is the average elevation of continents. The other one is a peak at almost -5 kilometers that corresponds to the abyssal seafloor.
Statistically what this tells you is that the process by which these elevations are distributed is not random. In fact, there are probably two different processes, one that makes continental crust and one that makes oceanic crust. Circumstantial evidence is just not enough! Each piece of Wegener's evidence was dismissed at the time because he couldn't come up with a physical mechanism that would work to move continents laterally apart from each other.
I also think no small part of it is that scientists don't necessarily love it when outsiders to the subdiscipline come in with a novel idea. True years ago, true today. Since Wegener was trained as a meteorologist, many geophysicists were skeptical of his ideas right from the start. Wegener knew that the sinking land bridge idea would violate isostasy and so he thought the continents did actually move apart from each other.
He actually thought continents would plow through the sea floor because the mantle is viscous. Think about trying to push a carpet across your floor just by shoving on one end of it.
This sketch is much closer to our conception of how plate tectonics actually works. Plate tectonics is a theory. The Earth remains the same size. That means if you create new crust, then crust has to be consumed somewhere else, and we take care of this with a subduction zone like the one shown here where sea floor goes down and gets recycled into the mantle. So this is just a sketch and we will flesh out more about how this works as this course progresses.
I think it is interesting to consider how long the plate tectonics revolution took to unfold. Consider that Wegener published "Origin of the Continents and Oceans" in in which he laid out the circumstantial evidence that indicated the continents had once been joined, but plate tectonics was not accepted as a theory until about Let's put that length of time into human perspective:.
The Yankees won the World Series twenty times between and , , , , , , , , , , , , , , , , , , , and You may opt-out by clicking here. More From Forbes. Jul 23, , am EDT. Jul 15, , am EDT.
Jul 8, , am EDT. Jul 1, , am EDT. Jul 20, , am EDT. Jul 19, , am EDT. Jul 18, , am EDT. Jul 17, , am EDT. You don't actually believe this? There are so many problems with this idea. Where did the extra mass come from? Where did the water come from? If you look at the animation you can see that the continents are actually morphed in all possible ways to fit with the preconceived model. Of course it fits if you just morph it any way you like.
There is science and then there is just crap like this with nothing to back it up. I have no idea where the theoretical extra mass comes from, but I wouldn't think it unreasonable that the Earth is gaining mass from the Sun. Although, it wouldn't really even need to have extra mass if the earth was just less dense.
Not unreasonable to suppose the Sun causes that sort of effect either I was taught that the eastern Canada and New England were probably slowly rising in a rebound effect after the weight of the last Ice Age glaciers was removed.
And that the southern part of the eastern seaboard was slowly sinking due to a concomitant seesaw effect. Whether that is true or not, it does have me wondering what the increase in sea level may be doing to plate tectonics. Is the weight of this increase enough. The Earth's ocean surface area: ,, sq km from worldatlas.
A conservative estimate of the amount of sea level rise from AGW over the next 75 years, give or take, seems to be around 10 cm. Weight of 1 cubic meter of water: Especially as I want to talk about weight and not mass. That seems like an awful lot of weight to take off of Antarctica and Greenland. If the continents are actually floating on the mantle, then these two would become more bouyant as all that ice melts away.
So the question for geologists is to what extent would the rise of Antarctica and Greenland affect the plate tectonics? Bearing in mind that this weight has been transferred to the ocean floors at roughly 14, tons per sq km?
If you want to find stuff in the Earth, then you hire a geologist. Where do you think the silicon in the chips, the gold in the connectors, the indium in your lcd display, and the plastic in your computer comes from? To find things in the Earth that people need, geologists develop theories to better understand how the Earth works, and how natural. Grad school prof.. I dunno. Spent a whole day's lesson explaining its flaws.
The bizarre thing was he was supposed to be teaching U. Bizzare drift frightens Continentals. No, a Pennsylvanian school with a habit of promoting looking for good coaches and giving them teacher positions to save money. This guy was softball. Not that the other chemistry teacher was much better.
Replace "Remember the Titans" with self-written poetry readings. There were a few more, but that is not here or there. You got a Vogon chemistry teacher. My hearty congratulations and deeply-felt respect on surviving that captivity.
What is it that uh he pretended to fumble for the word qualifies you said one student in the coach's English class. Pretty much the whole point of TFA is that it took a half-century for Wegener to be vindicated. Continental drift theory was not generally accepted until the s, and I remember that in the 70s there was still considerable debate about whether or not it really explained the modern shape and placement of the continents.
It's not at all surprising that he ran into someone who still dismissed the whole idea as nonsense if he was in grad school in, say, the mids -- or even up to the 80s, if the pro. Wegener's idea of continental drift was correct, but he didn't have a good mechanism for how these continents could plow through oceanic crust to move. That takes a massive force, and there wasn't enough energy to do it. Later it was realized the continents were relatively light and floated atop moving plates.
That provided a mechanism where the internal heat engine of the earth could provide enough energy to make them move. It wasn't just stodginess that kept Wegener's idea from being accepted. It was also real physical objections. Now, in hindsight, it's "obvious". But it certainly wasn't at the time. The matching of geological features was intriguing, but without a mechanism for the continents moving, it couldn't overcome the objections. Science is a process, not the fact.
Real Scientist will follow the Scientific method, and based on the method it will either prove or disprove their hypothesis. For continental drift. You are going on the fact the contents would roughly fit together like a puzzle, so perhaps they were at one time put together.
That is all fine and good, you now have model to base your hypothesis on. Now other then just a though experiment, you need to go to the next steps and try to prove your theory. If you are unable. Excellent summary of the usual excuse for why leading geologist snubbed Wegeners theory. They had to invent suddenly raising land-bridges that spanned of kilometres between all the continents to explain away the identical fossil records, land-bridges that appeared and disappeared without any trace or explanation, or without any known mechanism to cause them.
The "anti-Wegeners" had even more severe problems than the "continental drifters" when it came to "mechanisms" explaining the data. Wegeners idea wasn't armchair speculation, he had lots of hard data from many different sources, data that had baffled scientist before.
Newton didn't have any "mechanism" or explanation on what gravity was or what caused it in his "Principia Darwin didn't have any mechanism explaining why beneficial traits to be inherited by the offspring, since DNA wasn't known, yet his work was widely accepted because it explained the observed data so well.
I think a much better explanation of why continental drift was suppressed with quite some vigour, is Not-Invented-Here syndrome, group-think, and conservative and stagnant leading scientists suppressing new theories, rather than any sensible scientific process. Of course they were real physical objections. They were based on models that were wrong, but were the ones available at the time. To say that it's not a physical objection is to demand clairvoyance.
Wegener himself knew that he didn't have a fully valid dynamics for how the continents could move. He knew that it was a very reasonable seeming explanation for his observations and proposed some initial models. There are many things that are reasonable to the point of being obvious that are nonetheless wrong. Continents don't "drift" on the ocean like Wegener imagined, rather the motion of continents is caused by continental and oceanic plates engaging in tectonic events.
Chamberlin had launched his career with an iconoclastic attack on establishment thinking That happens all the time. Remember Einstein's resistance against quantum physics, even though his paper on the photoelectric effect was what started it. Scientific revolutions don't happen by convincing people but when the old guard dies. I don't think that's all that correct either. Plenty of naturalists that objected initially to Darwin were won over in his own lifetime, and most certainly while Einstein objected to QM, some of his own peers accepted it in due course.
The "old guard" is not some homogeneous band of group thinkers, but is as diverse in view as the new guard is. Even Einstein himself modified some of his views, calling the cosmological constant that he had inserted into GR "the biggest mistake" of his career of course, the. Of course. But there is always a core of older scientists who don't get it, which keeps any new theory from being universally accepted until those folks die.
In the meantime the nonscientific folks say "See, it's controversial! I don't buy it. Give me an example, because the one's provided so far; Einstein's objections to QM and Victorian naturalists objections to Natural Selection, don't prove your point at all, quite the opposite, they indicate that scientists, when presented with a good theory, will give it due consideration.
Einstein may have had his objections to QM, but even his own peers were giving away to it, because it explained observations very well. If what you said was true, theories would come in fits, only when the. I believe the term "Pseudoscience" is reserved for "not even wrong" type things. The scientists of the era considered him incorrect in his conclusions, not pseudoscientific.
The scientific method is based on the idea that you create theories, present them to the world who tear the theory apart and examine it, then create better theories if they can. Putting forward a new theory that gets challenged, argued over and torn apart is not pseudoscience.
I agree entirely. I think even among people who like science, there's a lack of appreciation for the philosophy of science and the value of wrongness. In fact, even in the scientific community, we don't dedicate enough effort to assuming hypotheses might be wrong. Confirmation bias is a harsh mistress and we don't do enough to fight her.
Wegener was correct about the continents moving around, and amassed plenty of evidence that the continents were once grouped together into the supercontinent of Pangaea e. But he was completely wrong about the mechanism. He proposed that the continents were plowing through the ocean crust kind of like icebergs floating on the sea, but when you work out the physics of that situation, the ocean crust is too strong to allow that to happen continental lithosphere is too weak, and you'd crush them before being able to push them through the oceanic lithosphere even if a suitable force were applied.
So, without a valid mechanism that made physical sense, geologists rejected his model. Plate tectonics didn't originate until the s or s when people realized that, essentially, the oceanic lithosphere was moving along with the continents, being formed at mid-oceanic ridges and destroyed at subduction zones, so the physical problems with Wegener's original continental drift no longer applied. People often think continental drift and plate tectonics are the same theory, but they are fairly different.
The largely rejected original theory transformed into the new, modern one. Wegener still deserves a lot of credit for bringing together the evidence that the Earth's surface really did move, and by the s that motion was directly measurable. It's pretty cool to imagine that every year the distance between, say, Europe and North America, gets a few cm longer. Anthropological Global Warming AGW is a scientific theory, that has been shown to be quite correct over last number of decades.
Carbon taxes, crap and trade, green subsidies, etc. Nevertheless, they did, and their ridicule scared away most would-be pursuers of continental drift. Even in the controversy of those early days, though, the first traces of acceptance were visible. But that fruit needed proponents bold enough to cultivate it, and those were scarce. Maybe he was confident posterity would restore it. Either way, he kept searching, answering the barrage of criticism and censure with ever more refined proof.
He spent the summer and fall hauling supplies by dogsled to the research station miles inland, but as winter drew near, the locals he had hired deserted him. On Nov. The temperature had dropped below degrees Fahrenheit. Along the way he died, probably from a heart attack. On that front, it would take three more decades for the world to catch up.
As late as , a book rejecting continental drift included a foreword by Albert Einstein.
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