I got this e-mail this morning from a geology colleague. I’ve despecified it and made it gender-neutral:
I have a silly question about word usage and I’d love to hear your opinion.
Today I overhead [a biologist colleague] talking about continental drift, and I cringed. S/he used it in context with continents moving apart and how that can alter gene populations. I shudder whenever I hear my students use conti drift [sic], because I make the association of Conti Drift, proper, as explained be Wegener and replaced by seafloor spreading and Plate Tect.
After talking with [him/her], s/he said that continental drift is in common usage in bio and oceanography circles, and that s/he was specifically talking about conti drift, the verb (continents moving apart) rather than Conti Drift, the proper noun – the explanation by Wegener. I suspect “we” (geologists) use the phrase ‘plate motion’ where “they” (biologists) use ‘conti drift’, but to me, conti drift really isn’t quite right and “they” should be using ‘plate motion’, like “us”. Accordingly, I think that conti drift should really only be used in reference to Wegener and his notions.
Do you have a take on which is more proper?
Here’s what I think:
Continents move over time. They drift. They do this not by plowing through the oceanic crust, but with temporary “skirts” of oceanic crust forming and falling apart fore and aft of the more buoyant continental crust. Alfred Wegener’s ideas about this were partially right (continents are not fixed in their position on the earth) and partially wrong (in his notions about the relationship between continents and oceanic crust). We retain part of his Theory of Continental Drift (all caps: the proper noun) and reject part of it. With the advent of a deeper (pun intended) understanding of the seafloor in the decades following World War II, we came up with a new notion, that of seafloor spreading. New oceanic crust was generated at mid-ocean ridge systems, and extant oceanic crust was destroyed/distilled/recycled at subduction zones. This got added to the good stuff from Wegener’s legacy, and the result was plate tectonics. It’s additive:
continental drift + seafloor spreading = plate tectonics
In other words, plate tectonics is a theoretical explanation that covers both the motion of the continents and the structure and genesis of the ocean floor. So, continental drift (lower case) is a symptom of plate tectonics. Seafloor spreading is another symptom, or manifestation, or consequence, or expression, of plate tectonics. The continents are the long-lived portions of the plates; the oceanic “skirt” is ephemeral. As the continents drift, new “skirt” is knitted, and old “skirt” is unraveled.
So I think it’s fine to talk about continents drifting, especially if you’re a terrestrial biologist whose focus is limited to the continents. To be complete, I think it’s therefore also fine to talk about seafloor spreading without referencing the continental crust that also may be moving along as part of that same plate. For me, neither term carries the connotation that it has to be Considered in Capital Letters, and therefore independently of a fuller understanding of the lithospheric system.
I think this may be a pet peeve of word usage from my esteemed correspondent, but it’s not necessarily all that significant in the grand scheme of things. I’ve got my pet peeve words too, as listed in previous posts like these:
Words’ worth I
Words’ worth II
Words’ worth III
Words’ worth IV
What do Mountain Beltway readers think? Should the term “continental drift” (in lower-case letters) be junked in favor of “plate motion” or some other phrase?
I agree with you that ‘continental drift’ is ok to use, especially in biology. We are making things too complicated if we say that this term should be used in historical context only. Such details like the difference between ‘plate motion’ and ‘continental drift’ may amuse some geologists but professionals from other fields (like biologists) need not to be aware of these things.
I’ve always used ‘plate tectonics’ in conversation or debate.
In my experience, when I discuss global tectonics with people – particularly when debating those expanding Earth nutters – the usage of ‘continental drift’ causes confusion, as it refers to both the generalised motion of the continents as well as Wegener’s theory.
I would argue (somewhat semantically/pedantically) that the continents don’t really ‘drift’ under plate tectonics: oceanic crust moves with the continents as a plate, so isolating the plate as drifting is the similar to isolating an intra-continental craton as drifting. (Though ‘Cratonic Drift does sound quite cool!)
As continent motion is derived from being ‘pushed’ by ridge dynamics. This renders the phrase ‘continental drift’ moot for me.
Plate Tectonics has implicit within it, the explanation of why continents move, and – owing to the paradigm shift that it was – I prefer its usage, particularly as it is surprising how many lay folk actually are aware of the term.
My read on this is that the biologist in question should have used a different term – species isolation, or perhaps breeding population isolation – when they were talking about changes through time in genetic populations. Why should they muddle their observations with an assumption on a causitive mechanism that is outside of their field of specialization? The isolation of a gene pool could occur for a variety of geologic reasons, not all of which are directly caused by the seperation of emerged continental crust caused by plate tectonics. There could be a rise in sea level that isolates populations, continental glaciation that seperates populations, desertification that seperates populations, etc., etc.
I use continental drift when speaking to most people, since for some reason that’s what people are familiar with.
Wegener’s theory of continental drift was rejected by geologists at the time. Plate Tectonics is in a lot of ways independent of Wegener’s ideas, so technically, as I see it, it’s incorrect to say continental drift, capitalized or otherwise. And it really does miss something important, it’s really not the continents that are drifting, the seafloor is really important here.
I note your correspondent says that Oceanographers use the term ‘continental drift’, but I think that’s wrong also. Some people would argue that without Oceanography we wouldn’t have modern Plate Tectonics; you only have to think about seafloor spreading to see that that’s probably true. Most Oceanographer’s I’ve talked to explicitly say ‘Plate Tectonics’.
So I think since continental drift is the common term, that makes it (linguistically) ‘vulgar’. So go ahead, be as vulgar as you want!
I’m not overly concerned that biologists use lowercase “continental drift” when they are referring to the relative movement of the continents, though I’d probably use “plate tectonics” to communicate the same meaning.
I would, however, amend your equation.
continental drift + seafloor spreading = Expanding Earth
whereas
continental drift + seafloor spreading + subduction = plate tectonics
(One could also argue there should be a term for transform motion, but let’s not go there, okay?)
Nice. I concur in explicitly including subduction.
(In my mind, subduction is implicit as a part of Seafloor Spreading, but there we go again with the different meanings of these same terms…)
If you have subduction and seafloor spreading (and maybe throw in the transform motions), why do you need to put continental drift in the equation? Makes it sound like the continents are wandering around on their own. If it were up to me, I would kill off “continental drift” entirely and just use “plate tectonics.”
I use Continental Drift (uppercase) when talking about Wegner’s theory, Plate Tectonics when I’m talking about the modern theory, and continental drift (lowercase) when I’m talking about the observation that the continents are in motion, an observation explained by Plate Tectonics.
I hardly use continental drift. We cannot decouple the movement of continents from the movement of the plate where they are embedded. And the usage of continental drift helps to perpetuate the wrong assumptions from the first half of XXth century…
Plate motion is a more accurate terms, in my opinion.
… and we are talking about biologists, not about my local handyman. Shouldn’t a biologist have a better understanding of the basic Earth tectonic process? My 12 y.o. son knows the difference between “Continental Drift” and “Plate Tectonics”, and why being both correct, the former is just outdated.
As you say, continents do drift, and the discovery of continental drift was a critical precursor to the discovery of plate tectonics, so the term deserves to survive.
I get more worked up over “fault line.”
Oh yeah! “Fault line” is insidious and geometrically misleading.
Didn’t put forth a hypothesis based solely geographical features? I have never heard it described as a theory???
Anyway, I view it as an archaic term that should be replaced… as should “petrified”, but I won’t go there.
That should read “Didn’t Wegener put forth…
I’m all for using ‘plate tectonics’ and scrapping ‘continental drift’ … it shouldn’t be too big a deal for biologists or any other scientist to embrace this phrase.
To non-geologists, the two terms (continental drift and plate tectonics) are essentially identical, and there is no reason to make a fuss with non-geologists about the two terms. They both refer generally to the concept of the shifting of the surface of the earth. Continental drift connotes an artificial distinction between the land masses above and below the oceans, and reflects a perception error of seeing the world based on geography maps rather than the actual geologic process. I can understand why it annoys a geologist to use the more familiar but less accurate phrase. But people who use continental drift are not promoting some alternative view or a misunderstanding of plate tectonics. They are simply using an historical but less accurate term to describe the same thing, and are likely unaware that it suggests a fallacy concerning the relationship of oceanic and continental crust with regard to plate motion.
I dont think the common usage of continental drift has anything to do with Wegener, even though he coined the phrase. Whenever the idea began receiving serious attention in the 60s and 70s from geologists, they used the term continental drift because of the Wegener legacy, and that is why the term passed into the popular lexicon to mean the same thing as plate tectonics.
Other examples of the same linguistic issue would be “global warming” or even the term “granite.” Global warming is better described as global climate change, which is induced by greater heat retention. The term granite has a specific meaning, but is used generically to describe a host of other similar rocks that are described by geologists with more specific names.
Since the term continental drift does not create any active misunderstanding of the issue, its not worth making a fuss over.
@dmbeaster
I’m ticking the ‘disagree strongly’ box. 🙂
In my trawling of the web, I have come across many half-informed people who take historical or colloquial usages of concepts or phrases such as ‘Continental Drift’ as a gospel rendition of current scientific thought.
These misunderstandings are then widely disseminated in a variety of forms of media (a blog post on hollow earth being correct because “continents don’t drift”; Evolution being chastised by clerics because it is “only a theory”; Fox News ridiculing global “warming” because it snowed in Michigan in May).
New concepts must derive their labels from the class of observations that make up the conceptual framework that they describe for exactly those reasons outlined above.
There are far too many retrogressive and ill-informed people out there just waiting for the opportunity to spread misinformation based on lazy application of labels to people who are even less informed than themselves.
When the paradigm shifts, so should the label.
@dmbeaster … I generally agree that we need not make a fuss about it, but I’d say that if we start now w/ being more accurate then the future non-Earth science scientists (that are being trained now) can use ‘plate tectonics’ and ‘continental drift’ will be for discussions like the one right here that get into the history and lineage of terminology (which can be interesting sometimes).