Googling : Accretion of Earth, pulls up all sorts of interesting stuff.
Our (scientists) understanding of Earth Moon formation also keeps evolving and that’s where answers to length of day and tidal forces is to be found.
Lighter continental granite forming out of heavier oceanic basalts, does a nice job of explaining continental expansion, but continental expansion is way different that expanding Earth.
Happy hunting, let me know if you find something interesting.
Lighter continental granite forming out of heavier oceanic basalts, does a nice job of explaining continental expansion, but continental expansion is way different that expanding Earth.The case for an expanding Earth includes the finding (my annual reviews reference above) that all or nearly all of the continental crust was formed around or before 3 Ga. We have found no rocks older that that. That the cooling and crust forming would be world-wide and relatively uniform seems right to me.
Critics of an expanding earth need to explain how cooling was irregular enough to allow continental crust forming only on certain parts of the globe and why no additional continental mass was formed subsequent to 3 Ga.
The expanding Earth folks can say increasing day length can be explained by a combination of the Moon’s gravitational effect and conservation of angular momentum through expansion.
The critics of an expanding Earth need to explain what causes are associated with increasing day length.
The expanding Earth folks say that continental drift began with expansion.
I don’t understand how you think “Lighter continental granite forming out of heavier oceanic basalts, does a nice job of explaining continental expansion”. This idea seems to be that the crust of the full-size Earth cooled and produced “oceanic basalts” from which came the continental crust. The only method of continental crust forming from the oceanic basalts that I can imagine is volcanic. I have found no support for that idea. I believe I’m right in saying generally most volcanic activity is associated with subduction. In order to have subduction we first need to have a continent.
To me, all in all the idea of an expanding Earth explains more of what we know and does it better, but I’m still searching.
One associated question is how and when did Earth get its water. It looks to me like there may have been enough of it for it to have had an influence on crust formation. I think the “when” is important; with a molten surface what was present must have been in the atmosphere. I’ll bet I’m not the only one to consider that the Biblical story of the flood may have been a reference to the first time it was cool enough for rain. I think it is no wonder that we have so little hydrogen in the atmosphere. If we did have a lot of hydrogen in the atmosphere at some time the production of oxygen by the cyanobacteria could have produced a lot of water. I never have liked the idea that comets brought us the water. It all has to fit somehow.
I’ll bet I’m not the only one to consider that the Biblical story of the flood may have been a reference to the first time it was cool enough for rain.You don't think it's related to personal memory and story telling about the great destructive floods that occurred around the Middle East during past ten and tens of thousands of years, of which there have been many. Including impacts of rising oceans, and glacial damn collapses that impacted other populated areas.
Besides back in those Biblical days, the world was what you could walk in a few weeks. There was little conception of our planet, the globe.
But that’s a whole different topic. Why not start a new thread on it, if you want to explore.
As much as I’d like to get into the Earth’s geology, no time. Except that I think you’re limiting your information, your claims doesn’t hold up against the body of information that’s available. The water thing, is a way fascinating story that’s taken many twists and turns over the decades.
later
the great destructive floods that occurred around the Middle East during past ten and tens of thousands of yearsYes, I've seen theories that "the flood" could have been a reference to when the Atlantic intruded into the Mediterranean Sea at Gibraltar and to when the Mediterranean overtopped the land dam and filled the Black Sea. Evidence has been presented supporting the idea that humans inhabited some of those areas that are now under water. And there are the ancient stories of floods probably due to a variety of causes.
The flooding of the Mediterranean and Black seas would have been seen as violent and long term events by people living there, something totally unexpected, but without the water receding. Other ancient and Biblical era floods, especially around rivers and coastal areas, would have been short term events and likely not completely new experiences.
The one thing missing from all of these is the idea of water falling from the sky as a new experience, something that had not happened before. I haven’t tried to work out how the entire globe could have been under water all at the same time but we do know that areas of the planet have been at different elevations over time. To do more than question and speculate is above my pay grade.
I’m still looking for an easy way to correlate the changing length of the day to a changing diameter of the Earth. I’m just too lazy and too busy to get into the math right now. The one paper I have seen which does present a mathematical explanation seems just a little bit too far out in left field for me to buy into it. There may be something there but I don’t get it. I’ve been wondering about this for probably 50 years; to be honest I really don’t see the utility of a definitive proof of an expanding Earth, at least not for a layman like me.
It’s not science to take one sentence from a study and misrepresent it. The devil is in the details. Perhaps rereading the entire abstract might help:
Earth's Continental Lithosphere Through Time Annual Review of Earth and Planetary Sciences Vol. 45:169-198 (Volume publication date August 2017) First published as a Review in Advance on May 31, 2017 https://doi.org/10.1146/annurev-earth-063016-020525
The record of the continental lithosphere is patchy and incomplete; no known rock is older than 4.02 Ga, and less than 5% of the rocks preserved are older than 3 Ga. In addition, there is no recognizable mantle lithosphere from before 3 Ga. We infer that there was lithosphere before 3 Ga and that ∼3 Ga marks the stabilization of blocks of continental lithosphere that have since survived.
This was linked to plate tectonics emerging as the dominant tectonic regime in response to thermal cooling, the development of a more rigid lithosphere, and the recycling of water, which may in turn have facilitated plate tectonics.
A number of models, using different approaches, suggest that at 3 Ga the volume of continental crust was ∼70% of its present-day volume and that this may be a minimum value. The continental crust before 3 Ga was on average more mafic than that generated subsequently, and this pre-3 Ga mafic new crust had fractionated Lu/Hf and Sm/Nd ratios as inferred for the sources of tonalite-trondhjemite-granodiorite and later granites.
The more intermediate composition of new crust generated since 3 Ga is indicated by its higher Rb/Sr ratios. This change in composition was associated with an increase in crustal thickness, which resulted in more emergent crust available for weathering and erosion. This in turn led to an increase in the Sr isotope ratios of seawater and in the drawdown of CO2.
Since 3 Ga, the preserved record of the continental crust is marked by global cycles of peaks and troughs of U-Pb crystallization ages, with the peaks of ages appearing to match periods of supercontinent assembly. There is increasing evidence that the peaks of ages represent enhanced preservation of magmatic rocks in periods leading up to and including continental collision in the assembly of supercontinents.
These are times of increased crustal growth because more of the crust that is generated is retained within the crust. The rates of generation of continental crust and mantle lithosphere may have remained relatively constant at least since 3 Ga, yet the rates of destruction of continental crust have changed with time.
Only relatively small volumes of rock are preserved from before 3 Ga, and so it remains difficult to establish which of these are representative of global processes and the extent to which the rock record before 3 Ga is distorted by particular biases.
PS
7 Oldest Rocks Ever Discovered Isua Greenstone Belt. Age: 3.7 – 3.8 billion years. ... Acasta Gneiss. Age: 3.58 – 4.031 billion years. ... Alan Hills 84001. Age: 4.091 billion years. ... Genesis Rock. Age: 4.1 ± 0.1 billion years. ... Nuvvuagittuq Greenstone Belt. Age: 4.28 billion years. ... Jack Hills Zircon. Age: 4.375 billion years ± 6 million years. ...
I get the impression that you just think the expanding Earth notion is a very cool idea, so cool it just has to be true, and that’s that.
... and that ∼3 Ga marks the stabilization of blocks of continental lithosphere that have since survived.In other words, the blocks which form the continents we see today were formed and stabilized by about 3 Ga.
at 3 Ga the volume of continental crust was ∼70% of its present-day volume and that this may be a minimum value.To say that another way, between 70% and 100% of the continental crust we see today was formed by 3 Ga. All of the ocean floor is very much younger that that.
Neither of these statements say that the continents we see today were in their current form at 3 Ga, but they do say that the total area of the continents we see today did exist in some form by 3 Ga. They say we have no evidence of additional continental blocks forming or of any blocks having been destroyed since 3 Ga. Current consensus is that the blocks have migrated all over the globe and have joined to form several different giant land masses over time.
The dramatic change in day length tells us that the rotation of the Earth has slowed. The laws of physics are that this rotational slowing could not be achieved without a conservation of angular momentum. The effect of the Moon’s action alone is not consistent with the total slowing. An expanding globe with a relatively constant mass, and decreasing density, does a pretty good job of explaining it, especially in combination with the Moon’s influence.
It seems to me that there are folks out there who want an exception to Occam’s razor for the day length question.
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To say that another way, between 70% and 100% of the continental crust we see today was formed by 3 Ga.But that's incorrect. Read that sentence again
at 3 Ga the volume of continental crust was ∼70% of its present-day volume and that this may be a minimum value."Volume" being the key here.
You’re forgetting about subduction.
To say that another way, between 70% and 100% of the continental crust we see today was formed by 3 Ga.But that’s incorrect. Read that sentence again
at 3 Ga the volume of continental crust was ∼70% of its present-day volume and that this may be a minimum value.
“at 3 Ga the volume” [area times depth] “of the continental crust” [the part of the surface that had cooled and solidified] “was about 70% of its present-day” [what we see today] “volume and that this may be a minimum value” [could have been up to 100%].
You’re forgetting about subduction.The way I have seen it presented, only the newer (in geologic terms) ocean floor is subducted not the continental crust. Perhaps I'm wrong but I think "continental" refers to continents not ocean floor.
All of the various configurations of the continents I have seen postulated include only the original blocks formed by 3 Ga; they present no additional formation and no destruction or replacement. Its all the same original “stuff” that gets pushed around by sea floor spreading.
@ibelieveinlogic. Good catch there, about mainly ocean floor involved in current subduction,
but that doesn’t negate that continental crust does subduct through various methods and that deep-time does add up.
https://www.nps.gov/subjects/geology/oldest-rocks.htmDuring the immense span of time that has elapsed since life first emerged on the Earth 3.4 billion years ago, environmental conditions have changed and different groups of plants and animals have appeared, flourished, and disappeared. Our knowledge of this history is derived from the rocks that comprise the crust of the Earth. Over the years scientists have written the geological history of the earth by studying the composition, structure, and relationship of rocks and the fossils they contain.
The oldest rocks in the parks are Precambrian in age, from 3 billion to 600 million years old. This time interval saw the development of algae, fungi, and soft-bodied marine plants and animals. The distribution of Precambrian rocks is worldwide, but in the United States rocks of this age are found in the cores of major mountain ranges. They also occur in the Lake Superior region and in a few localities in the southwest.
also see, Geologic time scale
Precambrian (4600.0 to 542.0 mya)
Paleozoic (542.0 to 251.0 mya)
Mesozoic (251.0 to 65.5 mya)
Cenozoic (65.5 mya to present)
<blockquote>World’s oldest ocean crust dates back to ancient supercontinent (is ~ 340 million years old.)
EARTH 15 August 2016
By Emily Benson
<a href="https://www.newscientist.com/article/2100988-worlds-oldest-ocean-crust-dates-back-to-ancient-supercontinent">https://www.newscientist.com/article/2100988-worlds-oldest-ocean-crust-dates-back-to-ancient-supercontinent</a>
The oldest patch of undisturbed oceanic crust on Earth may lie deep beneath the eastern Mediterranean Sea – and at about 340 million years old, it beats the previous record by more than 100 million years.
Earth’s outermost shell can be billions of years old on land, but most oceanic crusts are younger than 200 million years. Understanding where they developed can help us figure out what Earth looked like as continents formed, broke apart, and shifted around the globe hundreds of millions of years ago. ...</blockquote>
continental crust does subduct through various methodsI believe this has to be speculation. I have seen no suggestion nor evidence presented anywhere of continents or parts of continents being subducted. If such a thing had happened that material would have been absorbed back into the mantle underneath other continental crust and thus there would be no evidence of it.
I have seen no suggestion that continental subduction has happened by any means much less multiple means as implied by your claim of “various methods.”
deep-time does add up.I have no idea what you mean by this.
I will take the liberty of re-stating my last post. All of the “super continents” I have seen postulated include only the original continental blocks formed by 3 Ga. The land surface area presented in all of these includes no addition to, and no reduction in, total continental crust. The “super continents” and the intermediate configurations shown include only the same original pieces of continental crust alternately being pulled apart and then pushed together by sea floor spreading.
To me the simplest explanation is that the globe cooled and a crust formed when it was smaller. As the globe continued to cool and expand the ocean floors were formed. Expansion without a significant increase in mass is confirmed by both radioactive decay and increasing day length.
The big thing that we don’t know is how and when the globe attained its water. I speculate that much of it came from hydrogen and oxygen formed in the mantle as radioactive decay products. Steam and other compressed gases are the power behind volcanic activity.
Wherever the water came from I speculate that it would have had a significant impact on the cooling and formation of the crust and it could be one reason the ocean floor formed differently from the continental crust. It seems obvious that the water at the surface would have been confined to vapor in the atmosphere until the surface cooled to less than the boiling point. It would be interesting to see what the atmospheric pressure would have been under those conditions.
Sorry for not being here; real life has been busy.
If what you say were true, then how do explain the composition of the land under the continental USA.
deep-time does add up.Do you know that plate tectonic moves roughly at the speed at which your fingernails grow? Yet we know that plates have literally moved across the globe's surface, that's what I mean when I say deep-time adds up. Miniscule changes add up to huge changes. after all 4,600,000,000 years makes for an awful lot of days. I'd love to add up the days, but we know that days were very short during the early part of Earth's formation and slowly increased with time, it would take a very smart person with a lot of time on their hands to do the calculations.
RESEARCH FOCUS: Understanding continental subduction: A work in progress Mihai N Ducea, MARCH 01, 2016 Geology (2016) 44 (3): 239–240, https://pubs.geoscienceworld.org/gsa/geology/article/44/3/239/132061/RESEARCH-FOCUS-Understanding-continentalA study by Froitzheim et al. (2016, p. 223 in this issue of Geology) adds new constraints to our rapidly evolving ideas and models regarding the process of continental subduction.
Classic plate tectonics concepts suggested that continents do not subduct.
Instead, when two continents collide at a convergent boundary following the consumption of an ocean by subduction, they accommodate the shortening within the lithosphere, which is thickened up to twice the normal values. The subducted oceanic slab that brought the continents together stalls and eventually breaks off and sinks into the mantle due to its negative buoyancy.
In contrast to that view, modern petrologic, tectonic, and geophysical observations have completely changed this picture still prevalent in many textbooks: continental lithosphere does, in fact, subduct to great depths at major long-lived collisional boundaries, and the two colliding plates can be separated by a section of convective upper mantle (mantle wedge) similar to the case of oceanic subduction.
There are three important types of observations supporting those assertions.
First, the discovery over three decades ago (Chopin, 1984) of ultrahigh-pressure (UHP) metamorphic rocks—crustal rocks in which the stable silica polymorph at peak pressure temperature conditions was coesite—documented that continental crustal rocks have been buried to >90–100 km in some orogens. After their initial discovery in the Alps, …
Second, refined plate-tectonic reconstructions and plate kinematics models for the Indo-Asian collision (van Hinsbergen et al., 2012) since its beginning, as early as the Paleocene, make very specific predictions regarding the total amount of shortening along this margin, which is significantly more than what can be accounted for by crustal shortening in the Himalayas (DeCelles et al., 2011). More than 1000 km of Indian lithosphere are missing and must have been subducted under the Asian continent. …
Third, seismic images of the ongoing Pamir–Hindu Kush collision system show that Indian lithosphere is being subducted to as much as 500 km beneath the surface (Sippl et al., 2013).
Between these lines of evidence, a compelling case can be built for the fact that continental lithosphere (crust and mantle) are subductable to great depths and significant distances away from the collision’s principal suture. One can further assume that only a small fraction of subducted continental crust makes it back to the surface of Earth, making UHP rocks extraordinarily important. …
There’s plenty more articles to be found with a little judicious googling.
As for water, wow, that’s a whole new ball of wool to unravel, considering the discoveries of the past decades, but Maddy is demanding another walk, so perhaps later, because it truly is fascinating. You know that water helps lower the melting point of rocks? Do you know that some rocks actually hold water?
Here’s a good lecture that goes over the basics. During the beginning it’s a bit slow, but the information does matter, so it’s worth listening to for valuable background.
Earth’s First Crust | Neighborhood Lecture Series
Carnegie Earth & Planets Laboratory
Earth is unique amongst the rocky planets in having two very different types of crust. Continental crust is composed primarily of silica-rich rocks like the granite of your kitchen countertops. Oceanic crust is instead almost entirely a black magnesium and iron-rich volcanic rock, basalt, like that erupted in Hawaii.
The continental crust juts above water because it is thick and granite is less dense than basalt so it floats higher on top of Earth’s interior. Oceanic crust sinks back into Earth’s interior on hundred-million-year timescales. In contrast, the buoyancy of continental crust allows it to survive longer at Earth’s surface.
Even so, only a very small portion of Earth’s surface consists of rocks formed within half a billion years of Earth formation. Carlson will discuss the continuing efforts to find these rare remnants of Earth’s oldest crust and what they can tell us about what our home planet was like in its infancy.
<blockquote>@believesinlogic. I speculate that much of it came from hydrogen and oxygen formed in the mantle as radioactive decay products.</blockquote>
Have you ever tried to find any studies supporting that. I've never heard of hydrogen or oxygen being an end product of radioactive decay, let alone that its happening within our planet.
<blockquote>Radioactive Isotopes, Their Decay in Mantle and Core
V. Rama Murthy, Springer Link
https://link.springer.com/referenceworkentry/10.1007%2F978-1-4020-4423-6_274
The Earth is a thermal engine driven largely by heat produced from the decay of naturally occurring radioactive isotopes in its interior. At present, the main radioactive isotopes are 40K, 235U, 238U, and 232Th, whose atomic percentages, radioactive decay constants, half‐life, and the heat production characteristics are given in Table R1. 26Al, an extinct radioactive isotope may have been an important heat source in the early history of the Earth. Many other radioactive isotopes are also present in the Earth but they play a negligible role in heat production, either because of their low abundance or their low heat producing capacity.</blockquote>
<blockquote>Earth's Layers: What Is Earth Made Of?
By Tim Sharp November 14, 2017
Reference Article: Facts about Earth's interior.
https: //www. space. com/17777-what-is-earth-made-of. html</blockquote>
<blockquote>Radioactive potassium may be major heat source in Earth's core
By Robert Sanders, Media Relations | 10 December 2003
https: //www. berkeley. edu/news/media/releases/2003/12/10_heat. shtml</blockquote>Here’s a video reporting on the latest and greatest findings regarding our Earth’s interior. I notice there are some others listed in my search, but this is the one I’ve already listened to, good ol Wonderful Person Anton. 
:
Folds within folds are amazing harmonic cumulative complexity flowing down the cascade of time. 
Great stuff…
Thank you. For my encore, where’s all the water hiding?
New Evidence for Oceans of Water Deep in the EarthWater bound in mantle rock alters our view of the Earth’s composition
June 13, 2014
www .bnl. gov/newsroom/news.php?a=111648
EVANSTON, Ill. — Researchers from Northwestern University and the University of New Mexico report evidence for potentially oceans worth of water deep beneath the United States. Though not in the familiar liquid form — the ingredients for water are bound up in rock deep in the Earth’s mantle — the discovery may represent the planet’s largest water reservoir.
The paper is titled “Dehydration melting at the top of the lower mantle.” In addition to Jacobsen and Schmandt, other authors of the paper are Thorsten W. Becker, University of California, Los Angeles; Zhenxian Liu, Carnegie Institution of Washington; and Kenneth G. Dueker, the University of Wyoming.
<blockquote>Rare Diamond Confirms That Earth's Mantle Holds an Ocean's Worth of Water
The diamond contains ringwoodite, which is water-rich but only forms naturally under the extreme pressure found in Earth's mantle
By Becky Oskin, LiveScience on March 12, 2014
scientificamerican. com/article/rare-diamond-confirms-that-earths-mantle-holds-an-oceans-worth-of-water/
A battered diamond that survived a trip from "hell" confirms a long-held theory: Earth's mantle holds an ocean's worth of water.
"It's actually the confirmation that there is a very, very large amount of water that's trapped in a really distinct layer in the deep Earth," said Graham Pearson, lead study author and a geochemist at the University of Alberta in Canada. The findings were published today (March 12) in the journal Nature.</blockquote>
Thursday, March 02, 2017Melting Temperature Of Earth’s Mantle Depends On Water
carnegiescience. edu/news/melting-temperature-earth’s-mantle-depends-water
Washington, DC—A joint study between Carnegie and the Woods Hole Oceanographic Institution has determined that the average temperature of Earth’s mantle beneath ocean basins is about 110 degrees Fahrenheit (60 Celsius) higher than previously thought, due to water present in deep minerals. The results are published in Science.
Earth’s mantle, the layer just beneath the crust, is the source of most of the magma that erupts at volcanoes. Minerals that make up the mantle contain small amounts of water, not as a liquid, but as individual molecules in the mineral’s atomic structure. Mid-ocean ridges, volcanic undersea mountain ranges, are formed when these mantle minerals exceed their melting point, become partially molten, and produce magma that ascends to the surface. As the magmas cool, they form basalt, the most-common rock on Earth and the basis of oceanic crust. In these oceanic ridges, basalt can be three to four miles thick. …
They found that the potential temperature of the mantle beneath the oceanic crust is hotter than had previously been estimated.
“These results may change our understanding of the mantle’s viscosity and how it influences some tectonic plate movements,” Sarafian added.
The study’s other co-authors are Glenn Gaetani and Adam Sarafian, also of Woods Hole. …
Journal reference: Science Advances, DOI: 10.1126/sciadv.1603024
This may be of interest:
New Google Ocean Maps Dive Down Deep
June 8, 2011
Up Close and Personal With Landscapes of the Abyss
The new 2011 Seafloor Tour will take you to interesting features found on the ocean floor, like the Mendocino Ridge, where the Juan de Fuca plate slides toward western North America. {CLICK TO PLAY}Starting today, armchair explorers will be able to view parts of the deep ocean floors in far greater detail than ever before, thanks to a new synthesis of seafloor topography released through Google Earth. Developed by oceanographers at Columbia University’s Lamont-Doherty Earth Observatory from scientific data collected on research cruises, the new feature tightens resolution in covered areas from the former 1-kilometer grids to just 100 meters.
The ocean floors contain dramatic landscapes--volcanic ridges, lofty peaks, wide plains and deep valleys—but most areas remain mapped in less detail than the surfaces of the Moon and Mars. The new, sharper focus is currently available for about 5 percent of the oceans—even at that, an area larger than North America--and provides spectacular scenery, including the huge Hudson Canyon off New York City, the Wini Seamount near Hawaii, and the sharp-edged 10,000-foot-high Mendocino Ridge off the U.S Pacific Coast.
https://www.ldeo.columbia.edu/news-events/new-google-ocean-maps-dive-down-deep
Very cool. Unfortunately my computer wasn’t able to open the app.
Although maybe it’s been incorporated into regular Google Maps because they do show a decent bathemetry. Yup Mendocino Ridge is a trip as is the Monterey Canyon which has fascinated me since they discovered an announced how amazing deep it was a few decades back. Another ocean that’s fascinated me, is those long trenches south of India that dramatize the dramatic runaway train it turned into before crashing into Asia. It’s like you can actually see the furrows it made in the ocean floor.
For some fairly fresh insight that fit right into the question of continental subduction:
The mystery of India’s rapid drift Posted by EarthSky in EARTH | SCIENCE WIRE | May 14, 2015India got a geologic boost that accelerated its drift toward Eurasia 80 million years ago, researchers suggest. The speed of the resulting impact created the Himalayas.
…
… Based on the geologic record, India’s migration appears to have started about 120 million years ago, when Gondwana began to break apart. India was sent adrift across what was then the Tethys Ocean — an immense body of water that separated Gondwana from Eurasia. India drifted along at an unremarkable 40 millimeters per year until about 80 million years ago, when it suddenly sped up to 150 millimeters per year. India kept up this velocity for another 30 million years before hitting the brakes — just when the continent collided with Eurasia.
Leigh Royden is a professor of geology and geophysics in MIT’s Department of Earth, Atmospheric and Planetary Sciences. Royden said: … https://earthsky.org/earth/mystery-of-indias-rapid-continental-drift-eurasia