Forget Sea Level Rise: Ocean Deepening Is Here!

Guest “truth is stranger than friction” by David Middleton

Alternate Title: The Cretaceous Sea Level Paradox

Oceans are at their deepest in 250 million years
And they have hardly been deeper in the last 400 million years than now.

Lasse Biørnstad
JOURNALIST
PUBLISHED Monday 08. june 2020 – 12:24
“It moves absurdly slowly,” says Krister Karlsen. He is a PhD candidate in Geophysics at the University of Oslo (UiO)’s Centre for Earth Evolution and Dynamics.

Karlsen is talking about how the Earth’s tectonic plates move – ever so slowly but surely, every single year. From a human perspective, this happens so slowly that it is almost imperceptible.

[…]

The world map 200 million years ago shows all the continents assembled in the supercontinent of Pangaea, a time when dinosaurs were well on their way to dominating the Earth’s landmasses.

Since then, the continents have been shifting farther and farther apart, and now they may be as far apart as they can be, says Karlsen. Give the Earth a few hundred million years more, and the continents will probably remerge into a new supercontinent. One proposed name for that possible future reunion is Pangaea Proxima, according to New Scientist.

The movements and age of tectonic plates have a great effect on the depth of the world’s oceans. Just over 100 million years ago, the oceans were around 250 metres shallower on average than they are today.

The older the seabed, the deeper it is, according to a new research article by Karlsen and several colleagues at the Centre for Earth’s Evolution and Dynamics.

[…]

Science Norway

Karlsen et al., 2020 is essentially a reconstruction of plate tectonics and the age of the oceanic crust over time.

According to their reconstruction (and others), 100 million years ago, during the middle of the Cretaceous Period, the oceans were about 250 meters shallower than they are today *and* sea level was about 250 meters higher than it is today. Process that for a moment… The oceans were 250 meters shallower, but the water level was 250 meters higher than it is today. This was due to the geometry and distribution of the ocean basins. While advancing and retreating ice sheets may have played a role in Cretaceous marine transgressions and regressions, the Cretaceous sea level paradox was a tectonic feature and a boon to humanity.

L-R: East Texas/Gulf Coast stratigraphy and Late Mesozoic sea level, carbon dioxide & temperature. The broad, shallow seas, high carbon dioxide and warm temperatures of the Late Jurassic to Cretaceous Periods formed the ideal setting for some of the most prolific hydrocarbon source and reservoir rocks on Earth. Click to enlarge. How Climate Change Buried a Desert 20,000 Feet Beneath the Gulf of Mexico Seafloor

During the Mid-Cretaceous, shallow seas covered many continental interiors…

“The extent of different 94 Ma ocean boundaries. (a) The maximum extent of the ocean crust in the ocean basins; (b) the extent of 94 Ma land, shelf, slope, and rise.” Goswami et al., 2018

While the ocean basins were, on average, considerably shallower than they are today.

Mid-Cretaceous bathymetry reconstruction. Goswami et al., 2018

“How about that, geology fans?”

Apollo 15 CapCom Joe Allen on Dave Scott’s discovery of the “Genesis Rock.”

References

Goswami, A.; Hinnov, L.; Gnanadesikan, A.; Young, T. Realistic Paleobathymetry of the Cenomanian–Turonian (94 Ma) Boundary Global Ocean. Geosciences 20188, 21.

Karlsen, Krister S., Mathew Domeier, Carmen Gaina, Clinton P. Conrad,
A tracer-based algorithm for automatic generation of seafloor age grids from plate tectonic reconstructions, Computers & Geosciences, Volume 140, 2020, 104508, ISSN 0098-3004, https://doi.org/10.1016/j.cageo.2020.104508.

105 thoughts on “Forget Sea Level Rise: Ocean Deepening Is Here!

    • We here in Texas sure do… You need about a 12,000 pound-test line and we recommend not fishing from a Bass boat, but something larger. Also, bring a bigger net.

  1. The science is settled. Settling? Subducting?

    How about ready for a reveal party instead. Regularly.

    • They should never have legalized pot. Look what you get.

      With the continents moving so much and tectonic changes, they have nothing by which to compare then with now. But, they can pretend and have another toke.

      NASA has even admitted that Earth is expanding which means looking back 250 or 400 million years is meaningless regarding sea level.

  2. So when the oceans widen is the process of deepening driven by increasing depth/mass of water or something else, like cooling ?

    I feel CO2 emissions must be at fault somewhere?

  3. First year geophysics: Young Atlantic Ocean spreading zone = warm bouyant rock = Higher sea level relative to contintents. Tectonics and isostasy have produced the biggest sea level changes in the Phanerozoic.

    • Quite so. Just look at the Hawaiian island chain and the Emperor seamounts (all part of the same chain). As portions of the Pacific plate move west, away from the spreading ridge, they cool and sink lower and lower, thus increasing the ocean basin volume. Coral atolls can keep a portion of the now sunken islands at sea level by the busy work of corals. All this paper is saying is that we now have a very old average ocean plate age, which leads to a deep ocean basin and low sea levels. Add in the fact that we are currently in a (comparative) ice age and that lowers levels more. When we go full glacial in the relatively near future, they’ll drop even more.

      • Yes Canuck, thanks for the explanation. But I do enjoy an opportunity to shout “OMG we’re all going to die!”

        • No we’re not… including those of us near the sea shore. Gravity helps sink plates too. Don’t worry. Be happy. Deeper ocean floors… yippie.

  4. It seems to me that sea levels must have been much higher during the so-called Roman and Medieval Warm Periods, because ancient structures built along shorelines then are ‘high and dry’ inland today.

    For example, Burgh and Harlech castles, which once stood at the edge of the sea, are now a kilometer or so inland, in spite of considerable subsidence of the land over the centuries.
    https://www.sciencedirect.com/topics/earth-and-planetary-sciences/medieval-warm-period
    https://en.wikipedia.org/wiki/Burgh_Castle_(Roman_fortification)
    https://en.wikipedia.org/wiki/Harlech_Castle

    I am guessing that the sea levels were higher then due to warmer global climate and polar melting. But CO2 levels, according to ice core records, have been remarkably stable around 200ppm, until the late 20th century.
    https://www.newscats.org/?p=10879

    This suggests that CO2 is not a major driver of climate temperatures.

    • @me
      “have been remarkably stable around 200ppm, until the late 20th century.”

      correction: “around 280ppm”.

    • Johanus, land is also rebounding upwards still from removal of 2-3 km thick ice of the glacial maximum that ended ~12-15k years ago. In Hudsons Bay, Canada, places where ships of the Hudson’s Bay Company could Harbour in the 18th- 19thC, are now wading pools. Rebound since disappearance of the ice sheets has been over 100m!

      • Is that why the huge grain port at Churchill was mothballed, not deep enough for today’s mega-bulk carriers?

        Meanwhile the Great Lakes are at all time record highs.

        • The northern shores of the Great Lakes are rebounding a lot faster than the southern shores, from the isostatic rebound from the melting glacial ice just 10,000-15,000 years ago. Therefore the lakes are tipping a bit in lowering the relative water levels on the northern shores and raising the southern lake shore water levels. It is really slow of course, but over decades and centuries is noticeable. This is one of the reasons in low water seasons why they say some of the ports and docking are getting more high and dry especially in the north, and why in wetter climate cycles, the lakes are really high, especially in the south. This will continue until things find equilibrium or another ice age advances, and starts all over again digging out the Great Lakes even deeper and bigger.

          The port of Churchill is rebounding as well, but still deep enough to host major shipping vessels. It could be dredged if required for the speed of any rebound uplifting and lower relative sea level. As of 2008, the port had four deep-sea berths capable of handling Panamax-size vessels for the loading and unloading of grain, bulk commodities, general cargo, and tanker vessels. Several of the limiting factors are a rickety old railroad that is the only access that just got repaired the last few years (it was washed out and owned privately by Omnitrax for awhile but now re-sold and fixed) and the fact the port is not year round and only open for about 4 months max. Traditionally, it was 90% used since 1932 primarily for shipping grain from the prairies under the Canadian Wheat Board, but when that got sold to a Saudi company, it was cheaper to ship the unsubsidized grain to the best markets which wasn’t always in the Churchill port best use. So it fell into less use and basically closed except for local traffic.

          The government of Manitoba proposed in 2010 that the Port of Churchill could serve as the North American terminus of an Arctic Bridge shipping service to Murmansk in Northern Russia. Containers from inland China and central Asia could potentially be transported to Murmansk by Russian railways, shipped to Churchill then transported south by rail to major destinations in North America, avoiding existing transport bottlenecks. With ice breakers, perhaps the port could be extended to 5-6 months of the year, since there is no multi year ice in access to the Atlantic Ocean or some of the southern Arctic Ocean. If things do warm a little in the north, then a bonus for the port of Churchill.

          https://en.wikipedia.org/wiki/Port_of_Churchill

        • I don’t like Great Lakes being near record highs 2 years in a row. Our boat dock is damaged from waves. Michigan could use some off that land “rebound” !

      • @Gary Pearse
        “… land is also rebounding upwards still from removal of 2-3 km thick ice of the glacial maximum…”

        Thanks for the info about Hudson Bay. It seems to be very close to the rebound epicenter for Canada, which was very heavily laden with glaciers during the Ice Age.
        https://en.wikipedia.org/wiki/Post-glacial_rebound

        But Harlech Castle is in Welsh Cardigan Bay, which was not covered with glaciers. Nor was Burgh Castle, which is in the English Channel, well south of the glaciers.

        Same goes for the Turkish port of Ephesus, which was a seaport for thousands of years, now several kilometers from the sea.

        I realize that there may be multiple reasons for the migration of these ancient ports towards the inland: falling sea level, glacial rebound, silting etc. Of course, some have migrated to underwater locations, e.g. Canopus. https://en.wikipedia.org/wiki/Canopus,_Egypt#Archeology

        Are there any published studies which examine all of these ancients ports and explain the reasons for each migration?

        • Oops, I was wrong about Harlech Castle. It is inside the ‘rising’ rebound zone:
          https://upload.wikimedia.org/wikipedia/en/b/b3/Post-glacial_rebound_in_British_Isles.PNG

          But I still think sea levels could also be involved with Harlech’s inland migration.

          Note that Burgh Castle (about 30km east of Norwich) is in the ‘sinking’ rebound zone. So if rebound is the ruling factor for these migrations, then the subsiding Burgh Castle should now be under water.

          But it is high and dry, well away from the shore.
          😐

          • Perhaps ’tilting’ of the whole island is a more apt description than part rising and part sinking?

          • The UK shows a seesaw effect. South coast was not glaciated, but hinged upwards, hence the white cliffs of Dover. Slowly slowly hinging back, hence the need for the Thames Barrier. Or so we were told. Maybe that stuff has been pc’d away these days.
            There are places where the depression of coastlines with the incoming tide is measurable. Probably also pc’d away.

          • Not sure about the White Cliffs of Dover comment. Remember the global sea level was 120-130 metres lower when the glaciers were sitting on the northern half of Great Britain.

      • Apparently the glaciers came down to mid-Wales, so half is sinking and half is rising. In any case, the U.K. rebound is only on the order of 10cm per century, so I still think that sea level was much higher in the MWP, leaving Harlech standing high above the shore as it is today.

        What else could it be?

    • Johanus: Your analysis violates the first rule of Climate Science: “It’s CO2 what done it!” (imagine that an English Bobby is saying that). CO2 from Roman’s profligate use of carriages, and the third world envy of roman privilege made them all want chariots, too, caused global warming and sea level rise, ultimately causing the collapse of civilization, just as CliSci’s predicted. So if we are serious about preventing the collapse of human civilization, we must destroy white-privileged chariot use. Simples.

  5. So…additional CO2 in the oceans, but only the man-produced CO2, is causing more rapid dissolution of the ocean bottom (yes, I struggled to get CO2 somehow related to deeper oceans) resulting in deeper oceans. This in turn…harms the cuddly little polar bears…by…

    Oh! Deeper oceans mean larger tidal waves as chunks of continental crust break off a slide into the deep oceans. The resulting tidal waves wash away the struggling cute little polar bears who have to swim to eat because all the ice melted back in…2014…or so according to Gore.

    We should all be ASHAMED of ourselves.

  6. Fascinating! Fun to imagine the world back then. So do such conditions give rise to fossil fuel formation? (more coal beds forming, etc.) Love your posts David!

    • I like to imagine the world at any point but now, to be honest. 😀

      But one of my favorite sub-genres of science fiction is the time travel to the past. Cliff Simak wrote several of those stories (Project Mastodon, for example).

      I need a globe designed for a few hundred million years ago…

  7. Something has to reduce if something moves apart to stay the same size and yet there’s no geological evidence to support that the Indian nor Pacific oceans has subducted and has in fact expanded just as the Atlantic and Actic and every other ocean/sea has by geological mapping and dating. By this article’s theory only an Expanding Earth theory explains how water has been reduced on land mass. By dating the ocean floor and the oldest rock formations are near the coastline of every continent and get younger as they get towards the faultlines and trenches. Can be dated with high waterlines to low waterlines and inland water sources reducing the same way. That aquatic flora and fauna fossils are found high on mountains of the oldest microorganisms to dinosaurs and fishes there is only rational thought and logic to reach a common sense conclusion that our Earth Expands. All the theories of massive subduction in our oceans and seas just don’t show evidence of it.

    • The Pacific plate is being subducted at both the American and Asian ends.
      This can be seen in action every time an earthquake occurs on the ring of fire.

      I don’t know where you get your data, but none of it even comes close to being true.

    • The theory which we call the Tectonic Plate theory is missing a force to move the plates.

      Do the tectonic plates move? Yes, absolutely.

      However, it is a fact that the plates are moving and have moved in complex ways (dozens and dozens of hard observational paradoxes that kill the mantel deep convection theory)…

      …that are absolutely impossible for the ‘mantel deep convection’ and Slab fall/drag hypotheses to cause/explain.

      The expanding earth theory is missing even a hypothesized mechanism to cause expansion, and regardless the expanding earth theory also cannot explain the observations.

      Geology is an odd field. It is constrained. There absolutely must be a real, very, very, large physical force to move the massive tectonic plates.

      Here are a couple of interesting reviews of some of the geological paradoxes.

      https://www.newgeology.us/presentation21.html

      http://www.davidpratt.info/tecto.htm

      In recent years, the kinematics of continental drift and sea-floor spreading have been successfully described by the theory of plate tectonics.

      However, rather little is known about the driving mechanisms of plate tectonics, although various types of forces have been suggested”14. Seven years later, in 1982, the assessment was:

      “At the present time the geometry of plate movements is largely understood, but the driving mechanism of plate tectonics remains elusive”3. By 1995 we find that:

      “In spite of all the mysteries this picture of moving tectonic plates has solved, it has a central, unsolved mystery of its own:

      What drives the plates in the first place? ‘[That] has got to be one of the more fundamental problems in plate tectonics,’ notes geodynamicist Richard O’Connell of Harvard University.

      ‘It’s interesting it has stayed around so long’ “25. In 2002 it could be said that: “Although the concept of plates moving on Earth’s surface is universally accepted, it is less clear which forces cause that motion.

      One of the most uncomfortable contradictions in current plate tectonic theory [is] the protracted collision between India and Asia. That the two continents should collide by subduction of the intervening ocean is reasonable; that India should continue to drive northward into Asia for some 38 million years after the collision is not.” 3

      In fact, “the protracted continental collisions in the Alps, Zagros, and Himalayas, which have continued to deform continental crust since the early or middle Cenozoic, are therefore anomalies in standard plate tectonic theory.” 1 “In plate tectonic theory, collision between two continents should quickly terminate because of continental buoyancy.” 1 “Buoyancy considerations predict that shortly after such a continent-continent collision, a new subduction zone should form”3 .

      “This has not occurred, and of the apparently important driving mechanisms for plate tectonics… slab pull clearly cannot be forcing India deep into Asia, and ridge push is generally thought to be too weak to accomplish such a task.

      • “…that are absolutely impossible for the ‘mantel deep convection’ and Slab fall/drag hypotheses to cause/explain. ”

        Why is it impossible? Because someone modeled it? I mean really… We have very little data about the interior of the Earth let alone the forces involved. Obviously the forces are enough to cause plate tectonics because we know plate tectonics is occurring. Unless you want to invoke magic, it’s the only forces working to spread the sea floor and move continents about.

        So…if a model says the forces are too small, the model is obviously wrong. What’s actually occurring miles underground is much more complex than most people imagine. I know this is true (with a high probability) because nature is ALWAYS more complex than people imagine.

        The continents do move about, the sea floor does spread, and the only rationale explanation is mantle convection. How deep it goes, how many interacting layers there are, and whether these vary depending on location are all mysteries for now – that doesn’t make it wrong, it just means we haven’t measured the mantle forces as yet.

        • Maybe one of those black holes they keep pointing at has its other end in the center of the earth, perhaps purely by chance. This keeps the deeps very energetic and hot while the material sucked into the black hole, resurfacing here, forces the overlaying layers to expand and move to make room. Does that not work as well as some other theories?

          • No, because a black hole big enough to generate that much energy would have swallowed the earth in less than 100 million years.

      • “The expanding earth theory is missing even a hypothesized mechanism to cause expansion, and regardless the expanding earth theory also cannot explain the observations.”

        There must be relevant hypotheses. I can think of two in less than a minute:

        (1) Radioactive decay of Iron nuclides results in daughter isotopes of lower density, expanding the earth’s core.

        (2) Core cooling causes variation in the crystalline structure of the iron core, creating lower density crystals and an expanding core.

        (3) Chemical transition of core iron crystals as a result of nuclear reactions creates new crystals of lower density.

        (4) Radioactive reactions within the core heat it up, expanding it.

        I don’t claim these are valid hypotheses, but here they are, such as they are.

        • Similar comment jorgekafkazar, the ever-present and ongoing role of volcanism brings takes high density rocks at depth (sg 2.8-4), melts them and otherwise turns them into lower density rocks at the surface (sg 2.5-2.8) plus gas plus water. Over billions of years it is turning high density rocks into lower density products (with greater volume) = expanding earth.

        • Altogether, those factors might increase the size of the core by 5 to 10 percent.
          However to explain the spreading of the continents, the earth would have had to expand by at least 400 to 500 percent.

      • Most people know that when you want to pull a pulley off of (or put on) a shaft you heat the Pulley so that it will expand. When you heat metal, stone, etc it will expand. When it cools it will contract. The earth is cooling therefor, the Earth will contract.
        I will leave it to the reader to calculate the difference in contraction from the cooling of the Earth and the expansion of the Oceans volume from the warming of the Surface of the earth and determine which will be the greater.

      • William Astley – “The expanding earth theory is missing even a hypothesized mechanism to cause expansion, and regardless the expanding earth theory also cannot explain the observations.”

        It is so painfully obvious to me that I fear I am just uninformed. The constant rain of meteorites and debris, that creates a layer of dust every day. Which I thought was why the older architectural stuff always gets deeper and deeper in strata.

        I mean obviously there is plate movement and Glacial rebound etc.

    • Evidences of the expanding Earth from space-geodetic data over solid land and sea level rise in recent two decades

      According to the space-geodetic data recorded at globally distributed stations over solid land spanning a period of more than 20-years under the International Terrestrial Reference Frame 2008, our previous estimate of the average-weighted vertical variation of the Earth’s solid surface suggests that the Earth’s solid part is expanding at a rate of 0.24 ± 0.05 mm/a in recent two decades. In another aspect, the satellite altimetry observations spanning recent two decades demonstrate the sea level rise (SLR) rate 3.2 ± 0.4 mm/a, of which 1.8 ± 0.5 mm/a is contributed by the ice melting over land. This study shows that the oceanic thermal expansion is 1.0 ± 0.1 mm/a due to the temperature increase in recent half century, which coincides with the estimate provided by previous authors. The SLR observation by altimetry is not balanced by the ice melting and thermal expansion, which is an open problem before this study. However, in this study we infer that the oceanic part of the Earth is expanding at a rate about 0.4 mm/a. Combining the expansion rates of land part and oceanic part, we conclude that the Earth is expanding at a rate of 0.35 ± 0.47 mm/a in recent two decades. If the Earth expands at this rate, then the altimetry-observed SLR can be well explained.

      So we also know more about SLR 😀

      Unfortunately without subtitels.
      But nice takes

      • “Combining the expansion rates of land part and oceanic part, we conclude that the Earth is expanding at a rate of 0.35 ± 0.47 mm/a in recent two decades”

        OK …let’s suppose that the earth is expanding at 0.35mm/a [noting that the standard deviation is greater than the mean so the earth could actually be shrinking] and suppose that this rate has been steady for some short geological period, say 10 million years.

        10,000,000 x 0.35mm = 3,500,000mm =3,500 metres

        Hmmnnn….so the claim , if the “expansion” rate is constant, is that the Earth’s diameter was about 25% less 10 million years ago – equatorial diameter 12,756 km now, 9,256km then.
        Going back to the Cretaceous-Tertiary boundary, 66 million years ago and the Earth has a negative diamater of around 10,000km.

        No wonder dinosaurs didn’t make it, they were living in a black hole

  8. According to Christopher Scotese’s great animation of plate tectonics and ice field coverage (https://www.youtube.com/watch?v=bzvOMee9D1o ), there were no polar caps or glacial ice fields on Earth during the entire Cretaceous period (145-66 million years ago).

    Conservation of mass would imply that, since we DO have polar ice caps and glacial ice fields on Earth today, the statement “the oceans were about 250 meters shallower than they are today *and* sea level was about 250 meters higher than it is today” cannot be true to first order, unless the mass of ice on land today is insignificant compared to the total mass of the world’s oceans.

    However, there is this general statement to consider: “Around 90% of the Earth’s ice mass is in Antarctica, which, if melted, would cause sea levels to rise by 58 meters.”–source https://en.wikipedia.org/wiki/Ice_sheet#:~:text=The%20Antarctic%20ice%20sheet%20is,to%20rise%20by%2058%20meters.

    Since the average depth of the world oceans today is about 3,700 m, a rise of 58/0.9 m would be a change of 1.7%.

    So, is that ~2% difference significant or insignificant?

    • But since when is the Antarctic under ice ?
      If these old existing historic maps are least true in parts, then early sailors saw Antarctic without ice.

    • During the last high-stand interval you could get in a boat in Colorado and take that boat across the seaway to the foothills of the Appalachians…..

  9. I’ve often wondered if the weight of the oceans causes subsidence, all by itself. After all, during ice ages, when ice is piled on land, that land subsides. When it melts, the land undergoes isostatic rebound. Sea water is even denser than ice, so it may be slowly subsiding, as this article surmises.
    Also, there is a lot of sedimentation that is washed into the oceans each year:
    “Therefore, the annual worldwide total of sediment reaching the ocean on all rivers, dammed and undammed, is about 12.6 billion tons, a decrease of about 10 percent from the amount that spilled into the sea in the prehuman era. With modern rates of erosion and no dams to trap sediment, about 17.8 billion tons of material would reach the coast each year, Syvitski says.” Mind you, that is EVERY YEAR.
    So, the oceans are being filled in by sedimentation, and the weight of that sediment adds to the overhead load of the water. Seems natural that subsidence would be expected.
    Kinda throws a monkey wrench into that whole ‘rising sea levels’ scare…

        • They don’t float on water, otherwise we could attach a couple of out board motors and decrease the shipping distance to China.

    • The average density of Earth’s mantle is about 4.5 g/cc. Compare that to the average density of sea water of 1.02 gm/cc.

      The density of sea water is much less than the density of mantle that it might be presumed to displace, so NO, the “weight of the oceans” does not cause land subsidence. Instead, look to plate tectonics to explain the difference in absolute elevations of Earth’s land masses, including seafloor. Liquid water just “rides along” and fills in the volumes of the Earth’s lower-most geographic topology, as it were.

      • Let’s be accurate here – density is only part of the story. Density and column height for a non-compressible fluid (non-compressible within the range of your conditions) determine the force exerted at the bottom of the column. So the force at the deepest part of the ocean today is greater than in the shallow sea eras.

        That being said, even the maximum force exerted by the water column is insignificant compared to the various forces (vertical and horizontal and everything in between) exerted by convection currents in the mantle.

        Same result, just a complete analysis. Sorry for being a pedant, but incomplete explanations do annoy me greatly.

        • WO, yes, a complete analysis would have to explain why the high pressure* developed from an average vertical column depth of the Earth’s continental crust from a mean height above sea-level (about 840 m) to a mean depth-below-sea-level of ocean basin floors (about 7,400 m) is not sufficient to cause “uplift” of ocean sea-floors.

          Within the first 16 km or so of the crust below its highest mountain peaks, Earth’s crust cannot be considered to be “self-leveling” due to rock- and/or ocean-developed vertical pressure gradients. But this is distinctly different than, and apart from, the issue of isostatic rebound.

          I believe that under your term of “convection currents in the mantle” you meant to include plate tectonic movements that result in both mountain range building and seafloor spreading/subduction.

          *A vertical column of Earth’s crust (at an average density of 2.6 gm/cc) that was 840 + 7,400 ~ 8,250 m high would develop a bottom pressure of about 30,500 psia, assuming no shear forces on its sides.

      • Google:
        What is the continental crust made up of?
        –Continental crust. The continental crust is the layer of granitic, sedimentary and metamorphic rocks which form the continents and the areas of shallow seabed close to their shores, known as continental shelves. It is less dense than the material of the Earth’s mantle and thus “floats” on top of it.–
        Granite: The average density of granite is between 2.65 and 2.75 g/cm3
        The continental crust is thick and old—typically approximately 30 miles thick and approximately 2 billion (2 × 109) years old

        It floats.
        Ocean floor very thin and very young- and not less dense granite.
        But of course roughly balanced in terms floating, but probably low slow wave it’s floating on, there movements of mostly oceanic crust diving under continent crusts. Taking CO2 from floors, which later erupted along with SO2.

  10. Makes perfect sense, but I doubt the average citizen being told they are responsible for paying a carbon tax to stop an accelerating SLR would even understand all these factors that go into why sea level is sea level. Plus the fact that all sea level is local, relatively speaking, based upon a few dozen other factors going on all at once that determines sea level. The gravitational Geoid being a huge factor that is sort of built in to all ocean levels everywhere, being that the global ocean isn’t flat, relative to the centre of the earth. Many things going on at once that give us present local ocean level. Many books and papers have been written on all this, and is a fascinating subject probably still in its infancy.

    People seem to think the global ocean is a big bath tub and the more water that pours in from melting ice and expands from any warming, that the ocean level must respond exactly accordingly. As tectonic plates collide and push up mountains higher and higher, the ocean basin gets deeper and holds more water. More water transferred from ice sheets to the global ocean the last 20,000 years weighs more and further depresses the global oceanic basin crust. Which is still adjusting from the isostatic rebound of the previous glacial advance taking more water out of the global ocean pushing that continental crust down under the glacial ice while the global ocean had 400 feet less water over it, providing less weight to push down oceanic crust, with the oceanic crust rising with less water over 70% of the entire earth for the long time periods of glacial advances. Takes time for everything to adjust for major things happening not that long ago. We will understand this all much more in the future as we collect more real time (and historical) data.

    It is an argument that climate scientists also use to say that the Holocene High Stand was a result of oceanic crustal adjustment happening slower than the melting ice caps providing SLR, and that we are still adjusting both on land from isostatic rebound, and under the ocean beds that are still depressing from the extra weight of all the ‘new’ water that just melted 15-20 thousand years ago raising sea levels on average 400 feet. Long term sea level rise might be a moot point if the extra weight of the water just depresses the oceanic crust down allowing the global ocean to hold more water for the same area.

    The Earth’s mantle and resulting crustal movements is like silly putty and we are just going along for that ride in the scheme of things. If some think that climate change is ‘wicked’ complicated to understand, I would imagine trying to honestly understand how long term global sea levels react to everything, is even that much more complicated that probably very few average citizens even have a clue about. That’s why I don’t lose any sleep over SLR, and adaptation to SLR (if much) will be our only long term solution to living with local sea level. But try and explain any of this to your local city council about why declaring a Climate Emergency because the oceans are rising, and then we understand how futile it might be trying to argue Science, while the Climate Charlatans in academia just have to introduce Panic to the masses/media and Govt’s to get their way about how how Climate Change is bad and a simple carbon tax will just magically take care of all these problems, including the weather as well.

  11. No doubt about it, David. As I have previously mentioned I explored for copper-gold contact deposits in the Greenhorn Limestone member of the Mancos shale, which is around 90 my old. So we drilled a gold discovery in the Ortiz Mountains of New Mexico, and I worked on prospects in the same Mancos Shale near Helena, Montana. What an inland sea! Fossils? Spectacular! Gold? Yahoo!

    • I enjoy your posts Ron. I live in west central Colorado. An ex-coal mining engineer friend and I spend many hours every summer at 10K feet scouring for fossils. Lots of shells and some kinds of aquatic creature’s bones. Rocks are cool.

  12. One proposed name for that possible future reunion is Pangaea Proxima, according to New Scientist.

    Hmmmm …. Not very imaginative. How’s about “Pangea Redux” or “Pangea Together Again for the First time”?

  13. Deeper oceans means more cold sea water soa bigger capacity to absorb CO2. Is this another mechanism to explain falling CO2 levels since Pangea broke up??

  14. Went to Ephesus in Turkey. It was a seaside city when Anthony and Cleopatra honeymooned there. It was at least a mile from the Mediterranean.

  15. There is evidence that when the earth’s core started to crystallize roughly a billion years ago that there was a major change in geological activity, at that time.

    One of the most important unsolved paradoxes, in science,….

    …. is what is the physical explanation for the Cambrian Explosion of advance life, 570 million years ago. Why does life wait billions and billions years before advance life appears on the earth.

    The biologists have determined that evolution should solved the advance life problems billions of years earlier. There must therefore be a significant envirnomental change which itself makes advance life possible.

    The natural solution is that the earth changed roughly a billion years ago. And that change gave rise to deep oceans and raised the continents.

    The hypothesis, to explain the time of life, is that prior to around 600 million years ago, there was much less water on the earth’s surface, the continents were much lower than they are now, and the ocean basins were much less deep.

    https://www.sciencedaily.com/releases/2018/12/181212134354.htm

    Why deep oceans gave life to the first big, complex organisms

    Why did the first big, complex organisms spring to life in deep, dark oceans where food was scarce? A new study finds great depths provided a stable, life-sustaining refuge from wild temperature swings in the shallows.

    In the beginning, life was small. For billions of years, all life on Earth was microscopic, consisting mostly of single cells.

    Then suddenly, about 570 million years ago, complex organisms including animals with soft, sponge-like bodies up to a meter long sprang to life. And for 15 million years, life at this size and complexity existed only in deep water.

    North American continent is a layer cake, scientists discover and the top of the layer cake is less than a billion years old and that sediment (mostly limestone) is on top of 3 billion year old rock.

    https://www.sciencedaily.com/releases/2010/08/100825131445.htm

    The North American continent is not one thick, rigid slab, but a layer cake of ancient, 3-billion-year-old rock on top of much newer material probably less than 1 billion years old, according to a new study by seismologists.

    • “A new study finds great depths provided a stable, life-sustaining refuge from wild temperature swings in the shallows.”

      For most of the earth’s history there have been no polar ice caps and few glaciers. Accordingly the ocean bottoms have rarely been as cold or as oxygenated due to sinking surface water due to ice formation as is now the case. And there was no free oxygen in the atmosphere or oceans till about two billion years ago. Before that cellular metabolism was apparently sulfur based as is still the case at deep ocean thermal vents. In the Carboniferous the proliferation of large plants added to the geological and more primitive biological processes that deplete the atmosphere of CO2 or turn it into oxygen.

      Sulfur consumers may have preferred deep water but oxygen consumers needed surface water where competition for oxygen was sufficiently intense to drive the evolution of lung fish>>amphibians>>reptiles>>etc. Lungfish dominated the seas until they were displaced by reptiles, birds and mammals, and the lung atrophied (coelacanths) or evolved into a swim bladder (teleosts) as they took to the depths and polar climes in search of safer, still oxygen rich waters.

      The earth is always changing. –AGF

  16. Of course it makes perfect sense that older oceanic crust would coincide with deeper oceans. Projecting into the future, however isn’t a particularly easy task. Chris Scotese’ Paleomap Project http://www.scotese.com/future.htm
    does that out 50 MMY from now. What seems obvious is that although a significant amount of oceanic crust is consumed as Africa merges with Europe and the new mega continent moves to merge with North America there is still a fair amount of new oceanic crust that must be generated at the Mid-Atlantic Ocean spreading centre. There is probably someway of using Scotese model to figure out how much net new ocean crust is present at any given time going forward the next few hundred million years and hence when a new Super continent is formed.

  17. Surely the super-ocean that surrounded Pangaea was old, cold, and deep? We have virtually no record of this oceanic crust. It has all been subducted (perhaps some was accreted into continental crust and mashed up to buggery?) – we don’t know where the mid ocean ridges were, or any of the bathymetry. It’s a nice idea, and probably more or less correct, but really just conjecture.

    • …of course if the intracontinental seaways are closed to the main ocean, then this is irrelevant.

  18. David –

    Off topic, but I saw kids practicing baseball. I was filled with joy!

    Now I am wondering if my stupid governor will roll up in his 64, put the window down, and scream “you kids either start protesting or put your damn masks on.” Geez my Governor is a douche.

  19. As I read the post, the “thickness” of the oceans has increased by 250 meters during the last 100 million years to where it is today. Consider the volume of water this represents. And this decreased “thickness” of the oceans occurred during the middle of the Cretaceous period, when temperatures were much warmer and probably little to no ice present at either pole. Expansion would have been much higher during the Cretaceous period as well.

    I don’t think the total volume of water that has existed since water formed, has changed that much. Where was this volume of water (represented by 250 meters “thickness” covering 3/5 of the surface of the Earth) hiding during the Cretaceous period?

  20. What was the original composition of Earth’s atmosphere 1,500 Ma before life forms?

    I had once read that the atmosphere was MAJORITY N/CO2 and the sky appeared pink . . . instead of blue due to O2.

    Can someone point me to a source?

    Thanks.

  21. I once did a thought experiment … really as the basis for a never-written sci-fi novel.
    Explorers coming back to the Earth in it’s last days, about 5B years in the future, on it’s way to becoming a red giant, expanded to roughly the orbit of Venus.

    The earth at that point is tectonicly dead. The continents have all eroded away.
    The Earth is now covered with water – about 6′ deep. Probably tidally locked, so currents keeping the dark side warm to radiate away the hear from the huge red sun dominating the sky.

    Since then, I would have to add a more or less permanent line of thunderstorms (thanks Willis!).

    So … maybe the seas are getting deeper right now. I see them (in my imagination) getting a lot shallower in the distant future.

  22. The whole topic of continental drift/ocean floor spreading etc is geologically immature, in the earliest stages of investigation. If an author wants to extend study into ocean water depths and heights, the uncertainties of plate tectonics carry over into such study and make meaningful deductions almost impossible.
    Some teasers have already been raised here, like where the energy to move plates comes from. Another teaser looks at geological times older than about 500 million years. That is about the metamorphic age of spread floor at its outer boundaries. Question: what processes were at work before then, during the massively greater earlier times, when helps like magnetic stripes are gone? What did ocean depths and heights do then? Another teaser, what does one use as an ancient reference level against which to measure vertical movement? Another, how does one measure the historic quantities of water of crystallisation in metamorphic rocks and consequent variations in free water volume? One can go on for hours of pointless conjecture. For what gain?
    Another big question: apart from the valid scientific drive to complete global jigsaws, why are researchers publishing papers like this one, with possibly intended implications for climate change policies, when the uncertainties are so huge? Surely the vast majority of planning for ocean level changes can be measured with adequate accuracy and projected with high confidence, from the many tide gauges with century-long records. What more data do we need for most of our future planning?
    It is tiresome to read paper after paper based on conjecture and arm waving by often junior authors who seem desperate to find something, anything, to subvert the plain but inconvenient evidence from the tide gauges, nasty devices that refuse to yield alarming numbers. Geoff S

  23. Why are you all discussing this ludicrous article? You are like nerds discussing Star Wars as though it is real. To those who laugh at this shit, thank you, it makes me feel a little better about humanity and to those who give it a moments credence….sad.

  24. Similar question to some posed above:

    if the diameter of the earth was the same in the Cretaceous 100my ago as it is today, and all the current continents were not broken up and still part of a whole Pangea, would they not all be congregated on one side of the earth, with the rest as ocean?

    Big problem for rotational/orbital stability?

    • From the sun’s point of view, the earth’s equator (roughly) passes by at a rate of 1000 MPH. The poles at 0 mph. That means one hell of a lot of centrifugal force from inside the earth to the surface, (not just coreolis), forcing the equatorial areas to be bulged out. The result is called an oblate spheroid, and it means the poles are flattened and the center is bulged. It doesn’t take much imagination to figure out why it is that shape. Imagine a spinning top with flexible ‘skin’.
      The continents NOT responding to these forces is what is unimaginable. It is as if earth is trying to ‘fling’ the center continents off the earth. Not the most scientific example, but hopefully, it is an example of common sense about what must be at work here.

      • Just how do you imagine the continents would be “affected” by this centrifugal force?
        A slight tug towards the equator?

        • I would say the opposite – away from the equator. If I were to image the long term land mass arrangement, I would expect there to be continents around the poles, and nothing in the center, eventually. The atlantic spreading could very well be due to the centrifugal forces. But the most massive force is at the center of rotation.

  25. As always, Dave, your mini-geology lessons are both informative & fun. Keep ’em coming!
    Cheers — Pete Tillman

  26. Somewhat off-topic, but does anyone know why the University of Colorado have not updated their SLR graphs since Feb 2018?

    http://sealevel.colorado.edu/

    Apologies if I’ve missed a past WUWT post on this, but a quick search didn’t turn anything up.

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