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A cliff that changed our understanding of time (www.bbc.com)
152 points by MiriamWeiner a year ago | hide | past | web | 60 comments | favorite

You can now eat Hutton’s unconformity. Behold: Hutton’s Unconformicake :-) http://all-geo.org/highlyallochthonous/2011/01/the-baking-of...

> Siccar Point is one of the most important geological sites in the world – but it took a 62-year-old farmer to spot its significance

Calling James Hutton a "farmer" is really a twist in narrative, when it proceeds to describe how he was a semi-genius polymath/inventor educated in medicine and chemistry who only bought a few farms after becoming wealthy as a scientist then being alienated from upper society for having an illegitimate son.

I see you read 3 short paragraphs further into the article, where that was all explained in detail (except you missed the note that the farms were inherited from his father) ...

Considering that (according to this article) he later called agriculture “the study of my life”, perhaps “farmer” is an appropriate one-word summary after all.

As far as I can tell his relation to farming is limited to his obsession with the processes and geological side-effects of agriculture rather than the act of farming itself. Calling him a "farmer" would be quite a stretch, when you compare the typical archetypes of the two. Especially in the context of his contributions to natural history/sciences.

In regards to inheritance, this analogy reminds me of the two brothers who inherited a farm in East of Eden from their father. Just because you both own it doesn't make you both a "farmers". Only one brother worked the farm as a traditional farmer, even after becoming wealthy.

Also, I don’t think “farmer”, in those times had the same meaning as now. Farming was still very labor intensive, and land owners could be farmers without doing much of the work or even without being much involved in daily operations (if a large farm needs dozens of people to run it, the farms’s “CEO” won’t have much to do with digging through dirt)

Wikipedia contains a far better example of this phenomenon of a rock face in Argentina over the authors photo:


Source: https://www.wikiwand.com/en/Stratum

Edit: Very interesting article none-the-less. Thanks for sharing

Actually I was less than impressed with the rather poor HDR impression of the photos in that original article. Makes me think of all the wrong cheap tools around that makes dark skies, fluo greens and halos around everything....

Yes, it was quite disappointing after reading the introduction of the authors trip to the rock face on a boat trip to find the picture wasn't very revealing of the topic... the editing tried to highlight it but the pictures didn't do it justice.

I love Hutton's line "We find no vestige of a beginning - no prospect of an end"....

Hardly surprising that Edinburgh became the birthplace of geology - few cities have their geological wonders quite so blatantly on display.

I can recommend the Geowalks around Edinburgh: http://www.geowalks.co.uk/

> Hutton realised that the formation and movement of these rocks to create the coastline we see at Siccar Point couldn’t happen in sudden cataclysms over years or decades

Color me skeptical. Why couldn’t these be quickly deposited layers that were later turned upright in some cataclysm? Why couldn’t they have taken decades?

Yes I know it’s heresy to question long established science, but that is the essence of science is it not? Questions and skepticism :-)

Off to do more reading I suppose.

It's a great question!!

There are two key reasons from Hutton's era, and several others from the modern era.

The first argument is what we see being formed today. Hutton was the original proponent of the principle of uniformitarianism (a.k.a. "the present is the key to the past").

We can find environments producing similar sediments as those rocks today, and they form slowly. This is the key parts of Hutton's original argument: That cliff is made of sandstones that are similar to those forming on beaches and rivers just around the corner. However, the modern processes we see forming sandstones operate very slowly. We do see some rapid pulses of deposition, but then very long times between each pulse. It takes even longer for the sand to start hardening into rock (with the exception of calcite cementation, anyway, which can happen in a few decades). If you look at the rocks in that outcrop, you'll see that they are themselves made up of other rocks. Furthermore, they have pebbles and boulders of themselves (solidified as rock and then eroded) contained within them. To have a sandstone that has pieces of itself that have hardened into rock, been eroded away, and then re-deposited requires a long time with any of the processes we see operating today.

The next reason is scale. There are lots of processes that can locally deform things (e.g. a landslide), but very few that can consistently deform things in the same way across an entire continent. You can trace that same interval of upturned (folded) rock all the way across the UK (and North America and other parts of Europe, though that wasn't known in Hutton's day). What process could affect such a huge area in a very short time? If it did occur in a short time, why isn't the rock shattered instead of folded? (Materials deform very differently at different strain rates.) How do you fold kilometer-thick sections of rock over thousands of kilometers without it being a gradual process?

There's tons of other very clear reasons, but they weren't known in Hutton's day. The simplest answer is still to go look at the rocks. They demonstrate a clear record of environments you can see today. Coal mines played a large role in convincing people in the 1800's, as they preserve an immediately recognizable environment. You can see coal seams with stumps of trees growing through them (complete with roots). The stumps are snapped off by a river channel that cuts through. Next another coal seam with stumps in it, and then the same above. Do we have any reason to believe that trees would have grown dramatically faster in the past?

> We can find environments producing similar sediments as those rocks today, and they form slowly. This is the key parts of Hutton's original argument: That cliff is made of sandstones that are similar to those forming on beaches and rivers just around the corner.

This seems flawed to me. "We can find environments producing similar sediments as those rocks today, and they form slowly." That's kind of saying "Under conditions like today, things happen like they do today." But catastrophes are, by definition, not the way things happen today.

So this argument boils down to either "Catastrophes have to produce different-looking results than non-catastrophic processes" (which may be a defensible point, but requires defense rather than just assuming it), or else to an implicit assumption that catastrophes did not in fact occur.

The second option may require a bit of explanation. I can assume uniformitarianism, see things that can be formed by gradual processes, assume that everything I see that could be formed by gradual processes was in fact so formed, and then see confirming evidence for gradualism and uniformitarianism everywhere. But if in fact the same effect could be produced by a catastrophe, I don't have any evidence - just an assumption and a circular argument.

That's fair criticism. Let me rephrase the assumption: Can we assume that the same fundamental laws of physics are operating today as were operating in the past? If the laws of physics have changed, then yes, everything is out the window.

If fundamental physical laws have not changed, then we can use what we know about present-day physics and chemistry to constrain what events occurred and what processes were operating in the past. This is geology in a nutshell.

For example, you cannot produce the type of quartz overgrowths and cements observed there and many other places at near surface conditions (i.e. the processes that make sand a sandstone similar to the ones in that outcrop). The reaction requires higher temperatures, higher pressures and different fluids to reproduce experimentally.

So either the rocks weren't at the surface, or the surface of the planet was be pressurized to hundreds of times atmospheric pressure and and bathed in very hot, very reactive fluids.

Next, there are minerals in the sand and mud that had to be weathered and transported at surface conditions. If the surface conditions were dramatically different than today, the minerals we see would be unstable and would quickly change to a different mineral. (They can change back and forth, but you'd see pseudomorphs and other evidence of that happening.)

That puts constraints on the temperature and pressure of the Earth's surface in the past. It implies that the rocks started out at conditions not too different from today's surface, and then were subjected to conditions very different from today's surface.

Lets say the rocks were heated up in a giant kiln. You're dealing with a kilometer thick section of rock that's thousands of kilometers wide that has all experienced similar conditions. If the laws of physics are the same, we can calculate how long it would take to get the rocks from surface conditions to equilibrium at the necessary temperatures. Circulating hot fluids through the rock can speed this up by 1-2 orders of magnitude. It's still not particularly fast. Thousands of years at the minimum, and that's pushing things (rocks are good insulators -- they don't conduct heat well).

Next, the only non-supernatural way we know to get the rocks to those temperatures and pressures is to bury them beneath other rocks. That takes time, even if it's far more rapid than what we see today. You then need to exhume them back to the surface, which also takes time.

That outcrop is showing two complete cycles of the processes outlined above, with a third in progress. That's the point Hutton was trying to get across with that particular example. It's not even that there's slow deposition, etc, it's that there's evidence for multiple cycles of things that have to take a long time. The chemical reaction-based argument I made above is a bit different than what Hutton argued, but it's the same basic idea.

This is not to say that things are purely slow gradual processes and no unique or extreme events are recorded

The geologic record is actually dominated by extreme events.

For most rocks, what you see is not evidence of constant gradual deposition, but pulses of deposition. The rock record is mostly gaps. Most sedimentary rocks are actually records of extreme events like hurricanes and floods. Volcaniclastic rocks are records of volcanic eruptions (again, extreme events). The processes that shape the Earth are localized in space and time.

Also, there are several examples of rocks in the geologic record that could never have formed today. (e.g. search for komatiites) We don't need exactly the same processes to be in operation, we just need the same physical laws. The rest can be derived.

Finally, yes, we do frequently use modern environments as analogues. It's not circular reasoning to do so. You do need to be keenly aware of the potential for differences, but it's more akin to a large-scale experiment than a strict "this must be exactly what happened in the past". The time and spatial scales often make traditional experimental methods impractical, so we use modern analogues in those cases. The question asked when using a modern analogue is not "what is happening here", but rather "what underlying physical processes are responsible"? The goal is to constrain the parts that can't change or are unlikely to have changed.

Well, Britain and much of Europe was under an ice cap during the last ice age that ended 8000 years ago. The start of the last ice age was rather quick from a couple of months to a decade some say. It only needs a change of the gulf stream like a massive melt of Greenland and one could start like when Lake Agassiz leaked.

I was at a cave tour with family, and there were stalagmites and stalactites in an early room. The guide said "These took thousands of years to form."

Then later in the tour, there was a super thick layer of rock formations coating (layered mind you) a large section, it looked nearly identical to the stalagmites and stalacties from before, and the guide said "This all formed in a few months from a rush of hot mineral rich water from a broken geyser."

The guide seemed to realize how these two notions completed conflicted in the story telling, got all flummoxed, tried to justify the difference in time claims (no one even questioned the guide) and then awkwardly stopped talking and continued the tour.

I think there is a reasonable possibility we may be wrong about the timing of at least some rock formations...

The key in that case would be composition. Gyeser deposits are typically silica, and even when they're carbonate, they have a very distinct composition.

Also, I doubt what you saw was related to a geyser. It's not impossible, but I can't think of anywhere with volcanic activity and large caves formed in carbonates.

More likely, you were in the Carlsbad area, in which case you have some massive gypsum formations that are related to acidic waters formed by bacteria decomposing hydrocarbons. They form relatively rapidly (and the acidic waters formed the huge caverns). However, they're a completely different chemical composition than the stalactites just beside them (Gymsum vs calcite -- basically, gypsum has sulfur, which isn't in the rock around it, while calcite is what the "native" rock is made of).

Sorry for the second reply, but just for the technically curious, I found photos:

The government site says these stones are calcite, flowstone, round bubbly rocks. (formed in a same/similar manner as stalagmites?) Almost all the rocks in this cave are calcite. (I looked through a number of them on this site) [0]

This appears to be the thick layer of rock that I was told formed rather quickly. [1]

This is a clear picture, and it looks like large crystal growth? Which would explain the difference from slow stalagmite/stalactite growth? [3]

A detailed description, I honestly don't get all the chemistry/geology enough, but I have to trust they are being consistent. :P [4]

[0] https://www.usgs.gov/media/images/flowstone-formations-jewel...

[1] https://www.usgs.gov/media/images/cross-section-calcite-crys...

[3] https://media-cdn.tripadvisor.com/media/photo-s/04/53/d9/bd/...

[4] https://www.nps.gov/jeca/learn/nature/geology-of-jewel-cave....

Oh, yeah! Jewel Cave is a bit unique in this regard. There's a lot of sparry calcite (large, well-formed crystals) inside the cave. The difference is in the size and shape of the crystals. Large crystals like that can only form when they have lots of room to grow (i.e. when everything is underwater).

Those formed while the cave was flooded with water that was over-saturated with calcium carbonate. The rate of growth of a calcite crystal is a lot faster (inches per decade) under those conditions. The speleothems that are forming today grow slower (inches per century) because they're precipitating from a very thin layer/drip of water that only becomes saturated when it starts to evaporate or flow differently. Both processes are very rapid in geologic terms, but there's a significant difference in rate between the two.

Sure, "broken geyser" is what I had in memory, you are probably right about it being just "volcanic activity". :P

It was in the black hills, SD. I am not sure of the rock formation material, but I really go the impression it was the exact same kind of rock, which is why it seemed so contradictory. Maybe it was the guides first few days on the job and they were incorrect?

The cave was already formed, and the water coming into the cave caused all the formations. Could the waters have been of a different chemical formation? Seems like a reasonable explanation.

> it looked nearly identical to the stalagmites and stalacties

From casual observation, perhaps. But how about upon close scrutiny?

Who knows, I got the impression from the guide it was exactly the same kind of rock. It was even named by the guide, but this is from memory, and the guide could have been wrong.

Not all stalagmites are made of the same material. The guide most probably knew this, and you should have asked to get a correct explanation.

Nah, it was too awkward. The guide wasn't very old, and could have made an error.

Of course it could have been different material, but the cave is still there.



If there were a cataclysm large enough to upend a million tons of rock, what would you expect to see? A lot of rock smashed to pieces, perhaps? Do you see it?

Ditto for decades. What conditions are necessary to form rock quickly. Lava is quick but doesn't form that kind of rock. But anyway, to form it in decades, what conditions have to prevail? Do you see traces? I can't answer, but I expect the geologists who listened to Hutton's talk could.

Questioning long established science is anything but heresy. It is an essential part of it. Whoever taught you that that heresy nonsense should be kept far away from science. No offense.

There is a difference between questioning from a point of view of contributing new information and questioning for the simple pleasure of disagreement. The first position is necessary for the development of science, the second is a hindrance.

When the "long established science" is evolutionary biology, and to a lesser extent the geology of the age of the Earth, some of the questioning is not done in a sincere scientific spirit and it is not a good use of time to always treat it as if it is.

>Questioning long established science is anything but heresy

By "questioning" do you mean claiming you are certain that established beliefs are wrong? In that case, you should first very carefully study the reasoning behind those beliefs.

Or do you mean saying "that seems to me wrong, but this is something I have not studied, so explain the reasoning to me"

To wit: “that is the essence of science is it not?”

My “heresy” exaggeration was directed toward those who might become emotionally charged at the suggestion that Hutton misinterpreted the evidence :-)

But that implies you were trying to provoke an "emotionally charged" response, which is generally slightly frowned on here on HN.

Nope. Trying to prevent such.

There should be no recourse for asking questions like these.

It seems like many people forget that science is about what can be observed. Hutton's ideas are speculation. He can no more prove that is what happened than you or I can prove that the grand canyon took millions of years to get to the way that it currently is.

To say that this in any way proves or lends credence to "deep time" simply exposes the worldview of the individual who espouses the view.

You are correct to the degree that science begins from observations. However, dismissing one person's contribution to the body of knowledge in isolation ignores the vast amount of work in many different times, locations, amounts of detail, techniques used.

These interlock to lend incredibly strong support to one main interpretation, that the Earth is billions of years old and has had many different processes work on different parts over all that time.

To contradict all of that evidence at once is rather a bit more of a hurdle, and not so easily dismissed.

There is no 'proof' in science. You only have theories which can explain all currently known observations, and those which don't. And the theories which explain all known observations tend to have _predictive power_, which means that you can predict the outcome of some experiment or event using the theory and then verify the prediction through observation.

Even a prediction, however, doesn't "prove" the theory. Even a thousand or a million predictions don't. There's always a possibility, no matter how slight, that it was all one giant coincidence, and some future observation will throw everything into chaos.

All of that said -- the preponderance of the evidence-- and not just Hutton's observations but carbon dating and biology and chemistry, etc, etc, all strongly suggest the same interpretation, and one would have to have an astoundingly good reason for believing anything else.

Everything about the impossibility of proof that applies to our current understanding of "deep time" applies a million fold for any other theory which almost certainly lacks any explanatory or predictive power at all.

>There is no 'proof' in science.

Like many linguistic terms, the word "proof" has a number of different meanings. In science it has a different meaning than in logic or mathematics. As a consequence, scientists talk all the time about something being proved. For instance, a new chemical material is created, and a simple experiment is done to prove (= determine with certainty) how well it conducts electricity at room temperature.

As for theories, well-established ones usually never get disproved, they only are shown to be particular cases of larger ones. That is why physicists still study and make use of newtonian physics.

Unlike in maths, the concept of "proof" in a the context of something like geology isn't a clear cut concept, as Popper wrote:

"In the empirical sciences, which alone can furnish us with information about the world we live in, proofs do not occur, if we mean by 'proof' an argument which establishes once and for ever the truth of a theory,"

Which is a convenient argument to make, because it can be applied to the argument itself. But by extension, all we know would be that we don't know anything. Which is a good starting point, but not really satisfactory. The word em-piri-cal is related to ex-peri-ance and ex-peri-ment, so ... the idea is what isn't broken doesn't need fixing. And by a stretch, imperial is related, though the latter is from latin whereas the former is from greek; Both go back to "* per", which still exists on its own and in "perform", e.g. ... so I guess the idea is proof by construction. A program is isomorphic to a proof, according to the Curry Howard Correspondence, this is well known around here.

As a student of Physics and CompSci I had to defend the "pure math" perspective. Anyway, the circular reasoning of the quote is just the way the mind works. Still, the certainty can be quantified with Bayesian reasoning, but there has to be a threshold of what's transmitted.

>Hutton's ideas are speculation

No, they are not. They produced empirical predictions that could be tested. That is how science in general works. In fact, that is how you and everyone else operates in ordinary life.

And let me ask you, what about belief in a particular religion, is that provable?

> "we know the oceanic greywacke rock was formed some 435 million years ago"

You do not have data from 435 million years ago. You have a series of data that _seem_ to fit a model that you believe to be true. The only "fact" is what can be observed, but you were not there nor do you have testimony from people who were there 435 million years ago. That's speculation in my book.

> "But it was another 65 million years before the sandstone was formed."

Again, no hard data. This is speculative.

> “Hutton realised that the formation and movement of these rocks to create the coastline we see at Siccar Point couldn’t happen in sudden cataclysms over years or decades,”

Why not? There are other formations that don't make sense but were formed in much more rapid timeframe? Why not this one?

> And let me ask you, what about belief in a particular religion, is that provable?

Beliefs/worldviews can be based on any number of things: unsubstantiated tradition (whether right or wrong), widely attested-to eye witness testimony, or lies. And yes, I do believe "science" falls into this category as well.

Ref: Illustrations of the Huttonian Theory of the Earth (1802) from Charles Darwin's Library


Along with Joggins Fossil Cliffs in Nova Scotia [1], which were studied by Lyell and Darwin as well.

[1] http://jogginsfossilcliffs.net

If you're going to write a biographical piece (which is what this is) it's worth being precise. He was ostracized from polite society not for /having/, but /acknowledging/ a son born out of wedlock. The 18th century crawled with hypocrites.

Not much has changed since then. Look at all the "family values" politicians we find philandering and having children from affairs.

I don't think this changed much. Only the subjects.

It won't ever change, someone will always find something to be hypocritical about.

I think hypocrisy gets a bit too much stick -- recognising the right way, and doing things the right way are different.

I, for example, get my kids to bed at a sensible time and teach them good sleep hygiene whilst having appalling sleep habits myself. In some cases it's precisely because one realises the magnitude, or outcomes, of ones failure that one emphasises something one personally fails to achieve.

I imagine most politicians are just targeting a particular voting group however.

>I think hypocrisy gets a bit too much stick -- recognising the right way, and doing things the right way are different.

I think the correct definition of hypocrisy is pretending your are doing something you are not, and then expecting others to do what you "pretend" to do.

As a parent you are doing the right thing, but you are obviously not "pretending" that you are achieving what you expect your kids to do.

But there is a limit.

I had (and have) issues I deal with as a parent similar to yours, but when I was later called to the mat by my kids (when they got older) I told them "I am trying to do the right thing.", but that only goes so far. You may actually cause your kids to have the same issues if you don't solve yours, and if you continue to make excuses, you may cross over from simply failing to hypocrisy. (why should a kid "try" to maintain a good habit and be punished when they fail, if the parent doesn't?)

I have changed my children's behavior by changing my own, my motivation happened when I hit the hypocrisy wall. (on some issues anyways)

The politic issue is just sad and out of control though, are there no truly ethical and moral leaders left?

I don't reveal my flaws, eg to my kids (though I'm not lying to hide them) which makes it hypocrisy IMO.

I'd rather politicians do things morally, but if they realise the moral/ethical thing, fail, and cover up their failure but nonetheless support the position they know to be morally superior: I think I'd rather that than have them shrug and say "well I failed so that moral position isn't worth fighting for".

If I supported non-violent protest as a politician, but got in a fist-fight at a rally, hid that fact ... should I give up on promoting and supporting non-violent protest.

I don't see private failing as necessarily discounting oneself in public office.

A not uncommon situation is an adulterer being outed; they probably know better than others the harm that can come through such acts.

Thanks for your thoughtful and thought provoking response.

You are not supposed to comment "thank you", only upvote? But I had to. Thank you.

> I, for example, get my kids to bed at a sensible time and teach them good sleep hygiene whilst having appalling sleep habits myself. In some cases it's precisely because one realises the magnitude, or outcomes, of ones failure that one emphasises something one personally fails to achieve.

You aren’t pretending to follow the same guidelines that you set for your children, however. Your scenario isn’t underhanded.

And maybe we shouldn't tolerate being treated like children?

I found it amusing that I parsed your response in two directions. Since the original post was about hypocritical "family values" (Republican) politicians I immediately assumed you think Democrats treat us less like children. Then I parsed it again and came up with libertarians. Two fairly opposite ends of the spectrum and opposite understanding of being treated like children.

Interesting biographical piece but very little science (or even reference to science) in the article. To be expected I suppose for a mainstream article. Hutton seems like an interesting guy, historically, but he could hardly be considered a scientist, even by 18th century standards.

Stephen J Gould writes in “Time’s Arrow, Time’s Cycle: Myth and Metaphor in the Discovery of Geological Time” that

    Hutton did not draw his fundamental inferences from more
    astute observations in the field, but by imposing on the
    earth, à priori, the most pure and rigid concept of
    time’s cycle ever presented in geology—so rigid, in fact,
    that it required Playfair’s recasting to gain 

Geike writes

    In the whole of Hutton’s doctrine, he vigorously guarded
    himself against the admission of any principle which
    could not be founded on observation. He made no
    assumptions. Every step in his deductions was based on
    actual fact...
To which Gould says in the same book

    Geike’s mythical Hutton has been firmly entrenched in
    geological textbooks ever since.”

S. J. Gould, whose works I thoroughly enjoy, was not immune to casting a story according to his world-view, either, and these passages seem to be part of his rejection of the extreme uniformitarianism that he claims permeated geology at the start of his career. In other works, he writes approvingly of Hutton's perspicacity, while pointing out that his broader theories were speculative. The passages quoted above appear more critical of Geike than Hutton.

Hutton's dogmatic uniformitarianism must be regarded in the light of the then-prevalent, and equally dogmatic, catastrophist theories, which claimed that the Earth as we see it now was shaped by extreme events that no longer occur. In presenting contrary observations from the field, Hutton was at least as much a scientist as those holding on to the other view.

Thanks for the perspective. Gould clearly has an axe to grind in some of his writings. As to him being more critical of Geike than hutton, he has a LOT more to say about hutton in the referenced book. I didn't want to be too inflammatory but Gould has no such compunction in "Time's Arrow". He mostly criticizes Hutton for relying on metaphor and being reactionary to the catastrophists. He does not reject him out of hand though.

I think it's important to be able to criticize important figures in any fields history while recognizing the good that came from their disruption of the field. You can come to the right conclusion for the wrong reasons. In such cases it's natural to reject the conclusion as wrong, or to recast your morals to see the reason as right depending on your world view. Both are obstacles to scientific thought.

Please flag me if unappropriated but: the pictures used to illustrate this article uses HDR in a particularly unsubtle way (i.e. there are visible halos between the sky and the colors are way over saturated).

There are probably pictures of Siccar Point that reflect better the reality of the place than those gaudy images.

Also the saturation is cranked up to 11, and maybe some kind of diffuse-glow effect.

I don't think you're being inappropriate. The processing totally ruins what would otherwise be strong contrast between red-orange sandstone and greywhacke which is normally grey (plus whatever is growing on it) instead of the orange-ish colour it has in those particular photos. In other photos the unconformity is much easier to see.

Cliff Richard?

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