Talk:History of Earth/Archive 3

Edit suggestions for History of World
[Hello, Knowledge Seeker, Myles325 (abzorba) here. I am a medically-retired writer of manuals, with extensive experience in both creating and editing work of an essentially educational nature. Since discovering Wikipedia, I have become very interested in it, both for what it offers educationally, and for the concept in general. I read your comment on my note in the talk section of Timelines for Biological Evolution, where you suggested I look up this article. I must say that I am very impressed with both articles and would like to do some work on them. Because "History of the World" is quite long, I thought that a good way to proceed would be to post my corrections here, for by yourself and interested parties, prior to going any further. I am going to do this now. My comments on the text are in square brackets]

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[The changes in the first couple of sections are mainly stylistic, except for the deletion of the word “impossible”, used once in a way that I cannot recognise.

The History of the Earth covers approximately 4,567 billion years (4,567,000,000 years), from Earth's formation out of the solar nebula to the present. This article presents a broad overview of this period, with summaries of leading scientific theories where they pertain to the events described. Large intervals of time can be difficult to comprehend so the analogy of a single 24-hour period has been employed, beginning 4.567 billion years ago, with the formation of the Earth, and concluding in the present time. Each second of this period represents about 53,000 years. On this scale, the origin of the Universe, which occurred about 13.7 billion years ago with the Big Bang event, took place almost three days ago—two whole days before our clock began to tick. Origin of the Earth

Artist’s impression of a protoplanetary disc forming around a star, as seen from a distant planet.

[I do not think you should make mention of binary stars. There is are sufficient terms here for the novice to absorb without pressing unnecessary ones upon him].

Earth formed as part of the birth of the solar system: what eventually became the solar system initially existed as a large, rotating cloud of dust and gas. It was composed of hydrogen and helium produced in the Big Bang, as well as heavier elements produced by stars long gone. Then, about 4.6 billion years ago (fifteen to thirty minutes before our imaginary clock started), this vast cloud of dilute gas began to contract, possibly because a nearby star exploded, becoming a supernova and radiating shock waves into the gas. This contracting cloud became the solar nebula: its centre would become the sun. As the cloud continued to rotate, gravity and intertia caused the roughly spherical shape of the gas cloud to flatten into a shape more like a rotating discus, the proto-planetary disc. Gas and dust falling inward toward the centre of the disc became hotter as friction between the particles increased, until the matter at the centre was sufficiently concentrated for nuclear fusion to begin, igniting the fire that would create a new T Tauri star, our early Sun. The Sun's internal heat source came through its conversion of hydrogen into helium, the process of converting one element to another called nucleosynthesis, which releases vast amounts of energy.

Meanwhile, as gravity caused matter to contract, the remainder of the disc started to break up into rings. Small fragments collided and fused into larger ones..[2] One such agglomeration was approximately 150 million kilometers from the center: Earth. Others became the planets. As the Sun continued to contract and heat, fusion began, and the resulting solar wind radiating outward swept away most of the material in the disc that had not already condensed into larger bodies.

On the origin of the Moon there is still some uncertainty, although there is considerable evidence for the giant impact hypothesis. Earth may not have been the only planet forming 150 million kilometers from the Sun. It is hypothesized that another agglomeration of dust occurred 150 million kilometers from both the Sun and the Earth. This planet, named Theia, is thought to have been smaller than the current Earth, probably about the size and mass of Mars. Its orbit may at first have been stable but destabilized as Earth increased its mass by the accretion of more and more material. Eventually, Theia collided with Earth at a low, oblique angle.,,[3] about 4.533 billion years ago (perhaps 12:05 a.m. on our clock). The low speed and angle were not enough to destroy Earth, but a large portion of its crust was ejected. Heavier elements from Theia sank to Earth’s core, while the remaining material and ejecta condensed into a single body within a couple of weeks.Under the influence of its own gravity, and probably within a year, this became a more spherical body: the Moon.[4] The impact is also thought to have changed Earth's axis to produce the large 23.5° axial tilt that is responsible for Earth's seasons. (A simple, ideal model of the planets’origins would have axial tilts of 0° with no recognizable seasons.)  It may also have sped up Earth's rotation and initiated the planet's plate tectonics. [Suggest deletion of refs to Langrian points, and precise mechanics of collision. Not necessary here. Link to Moon should suffice]

The Hadean eon The early Earth, during the very early Hadean eon, was very different from the world we know today. Oceans did not yet exist, and there was no oxygen in the atmosphere. The surface was bombarded by planetoids and other material left over from the formation of the solar system. This bombardment, combined with heat from radioactive breakdown, residual heat, and heat from the pressure of contraction, caused the planet to be fully molten. Heavier elements sank to the center while lighter ones rose to the surface, producing Earth's various layers (see "Structure of the Earth"). Initially, Earth's atmosphere would have been composed of surrounding material from the solar nebula, especially light gases such as hydrogen and helium, but the solar wind and Earth's own heat would have driven off this first atmosphere.

A new atmosphere began to develop as the Earth increased in mass to about 40% of its present radius, with the stronger gravity better able to retain an atmosphere which included water. As the high temperatures attending the birth of Earth declined, a solid crust began to accumulate on the surface, re-melted in places by impacts from the bombardment of asteroids, much more prevalent in the early Solar System than now. Large impacts would have caused localized melting and partial differentiation, with some lighter elements being brought to the surface or released to the moist atmosphere. [5]

The surface continued to cool quickly, forming a solid crust within 150 million years (around 12:45 a.m. on our clock).[6] From 4 to 3.8 billion years ago (around 3 to 4 a.m.), Earth underwent a period of heavy asteroidal bombardment.[7] Steam escaped from the crust while more gases were released by volcanoes, completing the second atmosphere. Additional water, later to become the sea, came via bolide collisions, probably from asteroids ejected from the outer asteroid belt under the influence of Jupiter's gravity. The planet cooled. Clouds formed. Rain gave rise to the oceans within 750 million years (3.8 billion years ago, around 4:00 a.m. on our clock), but probably earlier. (Recent evidence suggests the oceans may have begun forming by 4.2 billion years ago-1:50 a.m. on our clock.)[8] The new atmosphere probably contained ammonia, methane, water vapor, carbon dioxide, and nitrogen, as well as smaller amounts of other gases. Any free oxygen would have been bound by hydrogen or minerals on the surface. Volcanic activity was intense and, without an ozone layer to hinder its entry, ultraviolet radiation flooded the surface.

Beginnings of Life [This material is of very high quality. It requires little further amendation.] […except that it is good practice to spell out what DNA stands for, even if you do not intend to define or describe it] [The first cell - Similarly, very good. But if you are going to talk about the history of DNA and RNA and their relationship, however briefly, then you do need to spell them out, and make a note of what they are]. [This is as far as I have progressed. At this stage, I might wait for some feedback before I go further.]abzorba 06:19, 4 October 2006 (UTC)

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Suggestion: The human history portion towards the end is very Eurocentric. — Preceding unsigned comment added by 99.61.252.128 (talk) 07:24, 29 February 2012 (UTC)

GA nomination?
What do you think, guys? Is this article ready for GA status? It's been a while since it was nominated. Cadiomals (talk) 23:16, 1 February 2012 (UTC)
 * Went on and nominated for GA. The two main problems were the lead and sufficient citations. I made sure both of those were fixed. Cadiomals (talk) 20:09, 3 February 2012 (UTC)

Regarding the spoken version of this article.
The spoken version of this article is NOT Computer read. It is NOT! Anything recorded by me is NOT computer generated. Please stop putting this designation on my little recordings. — Preceding unsigned comment added by Marmenta (talk • contribs) 07:22, 21 February 2012 (UTC)

First continents
First time commenter - be gentle. I am a professional geologist and former planetary scientist and I noted verbiage under 'First Continents' that seemed off:

'Mantle convection, the process that drives plate tectonics today, is a result of heat flow from the core to the Earth's surface.[29]:2'

I do not have access to the journal article cited there (Davies, _Nature_), but if you look at the physorg article cited under the Wikipedia article 'Geothermal Gradient' you find this key passage:

'For all this, however, Marone says, the vast majority of the heat in Earth's interior—up to 90 percent—is fueled by the decaying of radioactive isotopes like Potassium 40, Uranium 238, 235, and Thorium 232 contained within the mantle. These isotopes radiate heat as they shed excess energy and move toward stability. "The amount of heat caused by this radiation is almost the same as the total heat measured emanating from the Earth."

I suspect the Davies paper has been misinterpreted. I'd propose the following alternate text:

'Mantle convection, the process that drives plate tectonics today, is a result of heat flow from the Earth's interior to the Earth's surface.'

-- — Preceding unsigned comment added by Pgfrix (talk • contribs) 17:23, 19 April 2012 (UTC)


 * Good point! I made the change you suggested. RockMagnetist (talk) 18:09, 19 April 2012 (UTC)

Fact checking
I have been working to get this article ready for a successful GA nomination, and it is turning out to be more work than I anticipated. An agreement between text and citations seems to be more the exception than the rule. To make the task more manageable, I have inserted a TODO box in the talk page header with a list of the sections to check. If you have checked all the sources in a given section and they support the statements in the text, please check off that section. RockMagnetist (talk) 00:33, 20 April 2012 (UTC)
 * It's the number one problem I encountered also while trying to get this to GA, which is why I eventually stopped because it was too time consuming. It's been a while so I will try once again to find proper sources for the info in this article. Cadiomals (talk) 00:42, 20 April 2012 (UTC)
 * I think one section needs a fairly extensive rewrite: Origin of life. I'm tempted to just pillage some material from Evolutionary history of life and overwrite the first few paragraphs. RockMagnetist (talk) 01:59, 20 April 2012 (UTC)

Sandbox
As I am rewriting parts of this article to align the text with the citations, I find that some of the references don't obviously support any of the statements in the text. However, I hate to just throw these references away, so I have created Talk:History of the Earth/sandbox to store them for possible future use. RockMagnetist (talk) 05:47, 21 April 2012 (UTC)

Organization of Phanerozoic Eon
The table of contents looks a bit odd. The earlier eons are subdivided into qualitative events such as "Snowball Earth", but the Phanerozoic Eon is simply divided into eras. Is there a sensible way of dividing it into events? RockMagnetist (talk) 03:59, 1 October 2012 (UTC)
 * The mesozoic could for example be divided into "break up of pangea and mass extinction", "appearance of dinsosaurs", "appearance of birds", "extinction of dinosaurs". --Tobias1984 (talk) 07:32, 1 October 2012 (UTC)

Writing
I'm neither a geologist nor a science writer by trade, but am a writer, and cringed reading much of this article. Many of the problems either are entirely in, or are represented in, the lead, so I'll give that a thorough going over, and then briefly mention another issue:

'''The history of the Earth encompasses the development of the planet Earth from its formation to the present day.[1][2] Nearly all branches of natural science have contributed to the understanding of the main events of the Earth's past. The age of Earth is approximately one-third of the age of the universe. An immense amount of biological and geological change has occurred in that time span.'''

This is way too Latinate, but otherwise largely OK. "encompasses" is nearly wrong in the first sentence; yes, the field of study known as "the history of the Earth" encompasses that topic, but no sane reader is going to expect the first sentence of an article with this title to be about a field of study unless told it is. "concerns" or "discusses" or something of that sort - even "tells" - would be better. "contributed" is correct, though I'd say "helped us understand" instead. The last sentences? Hmmm. "The Earth is about one-third as old as the universe; in that time, everything we know of geology and biology happened." I'm not happy with the final clause (I wanted something like "that time gave rise to ..." but that implies teleology), but anyway.

'''Earth formed around 4.54 billion (4.54×10^9) years ago by accretion from the solar nebula. Volcanic outgassing likely created the primordial atmosphere, but it contained almost no oxygen and would have been toxic to humans and most modern life. Much of the Earth was molten because of extreme volcanism and frequent collisions with other bodies. One very large collision is thought to have been responsible for tilting the Earth at an angle and forming the Moon. Over time, such cosmic bombardments ceased, allowing the planet to cool and form a solid crust. Water that was brought here by comets and asteroids condensed into clouds and the oceans took shape. Earth was finally hospitable to life, and the earliest forms that arose enriched the atmosphere with oxygen.'''

Much of this is repeated word for word in the "Hadean" section. If the point is to emphasise how very far we are from how the Earth started (in other words, carrying on from the final sentence of the first paragraph), that can be done more briefly. In particular, let's see, "Earth formed around [date - I thought it was 4.567 but whatever], but when it formed, it was so hot, it was mostly molten. There was no oxygen in the atmosphere, there was little or no water, and there was no Moon.  Much has since changed." If the point of spending half the lead on the Hadean (something like 1/9th of Earth's actual history) is something else, I can't guess what.

I'm fairly certain it's factually incorrect that "the earliest forms [of life] that arose enriched the atmosphere with oxygen". Otherwise, there wouldn't be a gap of at least 1 billion years between the latest date discussed for the origin of life, and the "Great Oxygenation Event". I'm not aware of any species that has lasted a billion years; furthermore, if the earliest species emitted oxygen, why the heck doesn't the geology show the effects of that oxygen until the Proterozoic?

'''Life on Earth remained small and microscopic for at least one billion years. About 580 million years ago, complex multicellular life arose,'''

Life on Earth started something like 3.5 to 3.8 billion years ago. 3.5 - .58 is rather greater than one.

Do I completely misunderstand "stromatolites" ? I sort of thought they were fairly large objects that exist thanks to life. Sort of the coral reefs of the Archaean world. Granted the living creatures that created them were small and/or microscopic (why the duplicative adjectives?), but still. Also, many algae are pretty big. When did things like that get going? In the Proterozoic, or only in the Phanerozoic?

'''and during the Cambrian period it experienced a rapid diversification into most major phyla. Around six million years ago, the primate lineage that would lead to chimpanzees (the closest relatives of humans) diverged from the lineage that would lead to modern humans.'''

This is a whiplash-quick survey, isn't it? You've just privileged multicellular life, now you jump to us, not even mentioning dinosaurs along the way. And why select that particular event in human evolution?

'''Biological and geological change has been constantly occurring on our planet since the time of its formation. Organisms continuously evolve, taking on new forms or going extinct in response to an ever-changing planet. The process of plate tectonics has played a major role in the shaping of Earth's oceans and continents, as well as the life they harbor. The biosphere, in turn, has had a significant effect on the atmosphere and other abiotic conditions on the planet, such as the formation of the ozone layer, the proliferation of oxygen, and the creation of soil. Though humans are unable to perceive it due to their relatively brief life spans, this change is ongoing and will continue for the next few billion years.'''

I recently read Hazen's history of Earth, in which he claims that two-thirds of known minerals could only exist on a living planet. This is a stronger version of the fourth sentence here.

Broadly, this is pretty good, but probably should precede rather than follow the skewed potted history. This way, you go from specifics to abstractions, which is confusing.

In detail: Biological change probably didn't start "occurring on our planet" until rather later than "the time of its formation". For that matter neither did plate tectonics. I'm reasonably confident that most readers of this article experience humans as an "our", not a "their"; I even bet that's true of whoever wrote that sentence. And of course the whole thing's Latinate, though in abstractions that isn't as deadly. Hmmm.

"Our planet has been changing geologically ever since it formed, and ever since life arose, biological changes have been a constant too. Plate tectonics and evolution are examples of mechanisms driving these changes.  Geology has constantly affected biology, from supplying nutrients to the first life, to isolating populations to create new species; biology has affected the planet just as incessantly, adding oxygen to the atmosphere, creating the ozone layer, creating soil, and (according to some geologists) expanding the range of possible minerals.  Though human lifespans are too short to see much of it, both geological and biological changes continue, and will go on for the next few billion years."

OK, enough editing. The single biggest thing that made me cringe while reading the meat of the article was the way things happened over and over. Most obviously, at least one ocean "finally" closed in something like four successive periods. (I think this is the same ocean that *hasn't* "finally" closed yet, in that the Mediterranean is a remnant of it.) It would be helpful if much of the plate-tectonic verbiage could be replaced by maps, at least for the Phanerozoic, but I don't know if you can get permission to use any. Regardless, more careful wording would help.

And because I'm not a geologist, I usually can't provide that wording, but I can critique. Would y'all who are working on fixing this article want me involved less publicly? Or want me to stay far away? Or what?

66.212.64.252 (talk) 02:20, 29 January 2013 (UTC) Joe Bernstein, joe@sfbooks.com, not a registered Wikipedian.
 * I made an attempt to address some of your concerns in the lead. The middle lead paragraph is mainly concerned with giving a very brief and condensed overview of the most major events in Earth's history that directly affect it's conditions today; therefore dinosaurs are not of immediate concern as they, while popular, are only one group of the many that have existed throughout history. However I could not address all your concerns because either I did not understand them or saw no problems. I also don't have the time to make any significant changes to the body. You are always free to create your own Wikipedia account to make changes where you see fit, however. — Preceding unsigned comment added by Cadiomals (talk • contribs)


 * Hi. Thanks for being courteous, since I gather much of what I attacked was your writing.  In a nutshell, I was writing from an XP laptop where pretty much every program wants all the memory, so I didn't launch Acrobat Reader to consult the e-book I built a few nights ago and then started reading.  Turns out I conflated my complaints about "History of the Earth" and "Geological history of Earth".  The latter is where an entire paragraph of the Hadean section is used in the lead, and is where the Tethys closes in the Jurassic and then narrows in the Cretaceous (I didn't try to go any further, though I'm pretty sure its posthumous career continues).  So I apologise for that mistake and resulting confusion.  What I actually noted after reading "History of the Earth" was that it "needs a top to bottom rewrite for clarity, lack of useless repetition, etc."  Which is not very helpful, so probably my comments on the lead were more helpful.


 * The middle lead paragraph has two problems: one is that it's a bunch of specifics that precede but don't particularly illustrate a bunch of abstractions; the other is that it's an oddly chosen bunch of specifics.  I think I understand now some of the latter problem.  Sure, most of the events "that directly affect ... conditions today" happened in the Hadean - without it, no Moon, no water, no rocks, no Earth really, oh and no life.  But that isn't summarising the actual article, it's representing one take on what makes the history of the Earth interesting, or anyway something like that.  Why do you think this approach is the best way to introduce the article?  66.212.64.252 (talk) 03:21, 30 January 2013 (UTC)  Joe Bernstein


 * Joe, thank you for your comments. I did a lot of work on this article in an effort to get it ready for a good article nomination. My main focus was on making sure that the content is correct, comprehensive (within reason) and supported by the citations. However, I ran out of time and didn't complete the job. Although I was aware the lead was bad, I was reluctant to work on it. Leads are supposed to summarize the contents of the article, and I wasn't sure what I would be summarizing. Maybe that was a cop-out - I'll see if I can do a preliminary job on it.


 * I would be particularly interested in your comments on the sections that I have revised. I rewrote some of them extensively, and eventually hope to do the same for the remaining sections, so comments on the latter may prove to be moot. You can see by the checklist at the top of this page which sections Tobias1984 and I revised. RockMagnetist (talk) 04:31, 29 January 2013 (UTC)


 * Joe, I'm unable to find any reference in the article to oceans closing. Also, the only uses of "finally" refer to the third atmosphere and accumulation of oxygen. RockMagnetist (talk) 05:31, 29 January 2013 (UTC)
 * WP:SOFIXIT --Chris.urs-o (talk) 06:39, 29 January 2013 (UTC)


 * As I indicated above, mentioning the Tethys here was my mistake.
 * One reason I posted this was that I'd started thinking of how I'd change the articles, only to realise how much research it would take. (For example, getting the Tethys Ocean, Sea, or Zombie straight would pretty much require researching its whole history.)  So I wanted to find out whether an offer basically to work as a minimally informed editor would be accepted, or whether I'd be told "No, only geologists can make sense of this", or "Wikipedia doesn't care about good writing, please see the FAQ", or who knows what.  (Part of the reason I'm not a registered Wikipedian is that I've never set aside time to research how Wikipedia actually claims to work.)
 * So. Chris.urs-o points me, or you, or someone to a page headlined "Be bold! but be careful."  Which is, um, sort of the topic.  I gather what I'm supposed to do here is edit the page itself for style, and then you edit it back for content I damaged, and so on?  See, I think that kind of iterative process works better when it's possible to go meta.  In the ideal world, far as I'm concerned, that would mean editing by e-mail.  I could ask what the point of something was before deleting or rephrasing it, rather than just surprise you.  But you have my e-mail address and haven't written to me, so I gather that isn't appropriate?  The other alternative that incorporates meta is this page here.
 * (Separately, I don't get to volunteer you for other articles, so can only make this offer when articles actually get attention, right?) 66.212.64.252 (talk) 03:21, 30 January 2013 (UTC)  Joe Bernstein, joe@sfbooks.com
 * I'm not sure what you mean by your last comment. RockMagnetist (talk) 03:36, 30 January 2013 (UTC)


 * I think the best (fastest, most open) approach is to just make your comments here, and whoever has the time will respond. Don't worry about hurting my feelings; and don't worry about looking ignorant - if you don't understand something, lots of others won't. For that reason, I'm quite happy to have feedback from a "minimally informed editor" who has good writing skills. RockMagnetist (talk) 03:36, 30 January 2013 (UTC)

Biogenic Origin
Is there sufficient credibility to theories of the Biogenic Origin of the Early Continents of the Earth to include discussion here? See, for example: http://innovative-planetary-science.page.tl/Home.htm Thanks! --Lbeaumont (talk) 13:43, 15 September 2013 (UTC)
 * Your link is to a site promoting self-published material. If you have references which satisfy WP:RS then introduce them for discussion. Otherwise see WP:Fringe. Vsmith (talk) 15:02, 15 September 2013 (UTC)

Origin of Life
Although this section is very good, nevertheless I feel it does not consistently and sufficiently guide and inform the target reader (e.g. non-experts, students). It creates the impression there are competing theories for the O of L, with little consensus (e.g. RNA world, metabolism first, lipid vesicles, clays etc). It does hint that while most of these processes were probably relevant, RNA replication was critical, but not sufficiently clearly. For example it does state at the end of the metabolism section that metabolic aggregates probably could not evolve (Szathmary paper). But given the criticality (possibly literally!) of evolvability, this difficulty suggests to me that one should avoid giving Metabolism First equal status. I recommend re-writing so as to first give the likely ingredients for life (RNA -based selfreplication, competition via vesicles, metabolic contributions etc) and then explain that since an evolving self-replicating system would likely have appeared in an all-or-none manner (eg copying error threshold), it is natural to identify this as the critical step in the O of L. I'm not suggesting that any of the current material is wrong, or even misleading, but that there is probably sufficient consensus that one can lead the reader a bit more by the hand, so as to avoid the impression that everything is up for grabs. By the way, as an addition to the important cited Bartel paper on RNA replicases, I draw attention to a very recent paper (Attwater et al Nature Chemistry (2013) doi:10.1038/nchem.1781) that for the first time reports a ribozymal polymerase that can replicate itself. This is an extension of the Bartel work, in ice. 67.84.96.186 (talk) 13:20, 8 November 2013 (UTC)
 * I wrote a lot of that section, but I'm not an expert on the subject - I don't really know what balance to strike. You're welcome to rewrite it. If you do, though, please make sure that you provide citations for everything, because I have been trying to raise this article to Good article status, and one of the requirements is that the material be verifiable. RockMagnetist (talk) 21:00, 8 November 2013 (UTC)

Molten
I changed this sentence "Much of the Earth was molten because of extreme volcanism and frequent collisions with other bodies." to " Much of the Earth was molten because of frequent collisions with other bodies which led to extreme volcanism." As volcanism is caused by molten rock and not vice-versa. SUPERHETRODYNE (talk) 21:29, 6 November 2014 (UTC)
 * Thanks, SUPERHETRODYNE. RockMagnetist(talk) 22:38, 6 November 2014 (UTC)