Ever wonder what the Himalayas might look like in a couple billion years?
There you go, up above. (The buildings are for tourists because those are the Black Hills — see how dark the conifers look in shade? — and that lighter spot on the cliffs is Mount Rushmore.)
A Himalayan-like range once towered over the lowlands of supercontinent Columbia/Nuna here almost 2 billion years ago. (Weller and St. Onge)
Time and geological processes are rough on rock!
So are biological processes – those that turn rock into soil, for example, or break up boulders using powerful roots.
Wind, water, ice and the glaring Sun have all done a number on that granitic rock down through the eons, but those conifers and understory plants are actually “eating” the Black Hills, as well as prying apart nooks and crannies to get the best possible rooting.
Along with their ancient predecessors, these plants are active players in the ongoing erosion of a once-mighty range, as are all the little burrowing critters and other forms of resident life that have ever existed here.
You see, biology and geology go together like peanut butter and jelly. (The sandwich is our look into how cats (biology) evolved as well as the environments (geology) that shaped their evolution.)
Since there weren’t even vertebrates or vascular plants in Columbia/Nuna’s time, let alone cats, we’ll have to start off with a few general munches.
- Biology depends on geology for vital things like nutrients – including (but not limited to) the nitrogen, phosphorus, and potassium needed for DNA and metabolism (jargon alert) – and new habitats that encourage diversity. (Brown et al.; Burford et al.; Finke et al.; Kitadai and Maruyama; Knoll, 2003; Maruyama et al., 2013; Morris et al.; Mukherjee et al.; Valentine and Moores)
It’s not always happy camping, though.
Geology sometimes gets rough with biology, for instance, through large igneous province (LIP) eruptions that are often associated with supercontinents and can change evolution’s course. (Black et al., 2021a; Diamond et al.; Ernst et al., 2021; Keller, 2005; Racki)
- Of course, it’s a two-way street. (Burford et al.)
As we’ve seen, biology can alter and destroy rocks, but thanks to chemistry and physics, it has also given geology thousands of new minerals over the last 2.5 billion years. (Hazen et al.)
In addition to this, there’s another important effect that biology has on geology –
– Wait – shiny!
Minerals, colors, and Geotime Ginger
That’s an hour-long NOVA episode, but the intro is terrific and full of pretty things to look at.
Watch out, though. All the camera work, narration, story line, and exuberant geologists will draw you in – not a bad thing, actually, even if you’re not a rockhound.
It’s interesting and entertaining, plus there are good visuals of how early Earth developed – nice background information about what went on with our planet before Columbia/Nuna showed up. (Extra Bond points if you looked for a parkour chase in progress during the marketplace segment!)
As I understand it, during Archean times (and maybe Hadean, too), basaltic and then granitic minerals glommed together to form surface rocks and built cratons – the very first pieces of continental crust. Today, about 35 of these Archean continental cores, or shields, are known. (Bleeker; Carlson et al.; Ernst, 2009; Palin and Santosh.)
(Note: If you’ve heard of Ur or Kenorland before, be aware that I’ve chosen, for simplicity’s sake and also because I can’t directly link them to cats, to go along with sources like Bleeker and Bradley, and call those Archean assemblages supercratons, not supercontinents; these do deserve and will someday get their own post, but not now.)
Anyway, cratons and other crustal fragments like island arcs eventually came together to form a supercontinent – Columbia/Nuna – soon after Earth went into what NOVA shows us as Hazen’s “red phase.”
But Geotime Ginger, who’s following the more conventional geologic time scale, insists on yellow.
“Hi, folks! Relax and enjoy the colors. They aren’t official, and the time wheel isn’t 100% accurate, but it gets the job done. We’re not trying to earn a degree here, after all.
There’s a little more than half of the Precambrian to cover: the hellish Hadean (see the NOVA video); that anoxic Archean eon when microbes were doing photosynthesis, despite what NOVA says, just not the O2-producing kind (Arndt and Nisbet); and the mellow-yellow Proterozoic, when free-floating oxygen was more or less a thing, up to around the 2-Ga line – Columbia/Nuna’s startup.”
As far as cat evolution is concerned, close connections between geology and biology go back some two billion years to the time of the first true supercontinent – Columbia/Nuna – and the first eukaryotes (despite Ginger’s protests that it is a Phanerozoic color, I use green for Precambrian life).
As geologists currently read the rocky record, these new geological and biological breakthroughs happened at around the same time in Earth history.
Unfortunately, it’s not easy even for experts to see exactly how geology and biology fitted together here – only that it’s likely that they did. (Lindsay and Brasier; Nance et al., 1986, 2014; Rogers and Santosh, 2009; Santosh, 2009; Zhang et al.; but see Pastor-Galán et al.)
Let’s start our look into what is known at the Black Hills – those worn nubbins of an ancient Himalayan-like mountain range.
Then we’ll try to track down the supercontinent and its possible connections to life.
The Trans-Hudson Mountains
Mountains aren’t eternal. That is so hard to accept.
Yet it’s true. Empty air now fills much of the space above the Black Hills that used to be occupied, 2 billion years ago, by the Trans-Hudson Mountains of Columbia/Nuna.
“Trans-Hudson” is a scientific moniker. No one was around in those mid-Precambrian days to call the towering peaks something personal like “Abode of Snow.”
Speaking of names:
- “Hudson” or “Hudsonland” was one of the supercontinent’s earlier names. (Pehrsson et al.; Reddy and Evans)
- “Columbia” comes from a reconstruction that puts part of the ancient supercontinent near a section of North America’s ancient core that now is associated with the roughly 15-million-year-old Columbia River Flood Basalts – these are unfathomably old to us but quite young when you take the Precambrian perspective. (Rogers and Santosh, 2002)
- “Nuna,” based on another popular reconstruction, is an Arctic native word for “lands bordering the northern oceans.” (Meert)
In addition to the Black Hills region, geologists have also found Columbia/Nuna’s weathered Trans-Hudson remains in parts of Canada, including the delightfully named Reindeer Zone along and underneath southern Hudson Bay.
Multibillion-year-old Trans-Hudsonian bedrock might even still be present, below younger formations, at least as far south as the Grand Canyon and eastward into Scandinavia or beyond. (Chiarenzelli et al.; Corrigan et al.)
Almost two billion years of continental drift have since broken up this range and moved its fragments to different latitudes and longitudes, but the young Trans-Hudsons were huge – and they were just one of several mountain systems that formed in continental collisions as enormous Columbia/Nuna came together. (Chiarenzelli et al.; Corrigan et al.; Pehrsson et al.; Roberts; Rogers and Santosh, 2002, 2004; Weller and St. Onge; Zhao et al.)
The Trans-Hudsons probably rose much like today’s Himalayas are rising, only instead of India ramming into the megacontinent Eurasia, it was Archean microcontinents and island arcs colliding with what became the core of Proterozoic Columbia/Nuna. (Corrigan et al.; Weller and St. Onge)
Along the way, Corrigan et al. suggest, the Trans-Hudson mountain-building event shut down the poetic-sounding Songbird and Manikewan oceans.
In a similar way, today’s plate tectonics have closed off one end of the old Tethys Sea, turning it into the Mediterranean that we all know and love.
But one day those blue waters will be gone forever, and it will be possible to walk on dry land from Oslo all the way to Johannesburg.
This all may sound like fantasy – and it is speculative to some extent – but as we saw last time, such things do happen.
They’re shaping Earth’s future appearance right now – veeery slooowly.
It may or may not look like exactly like that, but in 250 million years or so, our planet definitely will be sporting new Himalayan/Trans-Hudsonian-style mountains on a new supercontinent!
Something old, something new – Earth constantly repeats itself.
Many, but not all, geologists suspect that supercontinents happen in cycles, but these aren’t easy to define. (Bradley; Bryan and Ernst, 2007; Nance et al., 2014; Pastor-Galán et al.; Yale and Carpenter)
However, the gigantic landmasses do leave their mark in the geologic record.
Collisions that build a supercontinent form chains of mountains like the Trans-Hudsons that geologists use to track down each giant. (Nance et al., 2014; Pastor-Galán et al.; Rogers and Santosh, 2004)
But the farther back in time they look, the more the evidence that they need to find has eroded away or has been squeezed, heated, deformed beyond recognition, broken up, reassembled, and/or shifted across the planet’s surface.
In Proterozoic Columbia-Nuna’s case, culprits behind this game of smash include younger supercontinents/megacontinents, so its rocky archives are really messed up.
In a nutshell, that’s why Columbia/Nuna is so mysterious. Apart from a few sites like the Trans-Hudson remnants, very little of its old formations are in good enough shape for studying now.
Experts nonetheless are trying to solve its mysteries.
Economics, world records, and the early evolution of life
There seem to be almost as many reconstructions and computer models of Columbia/Nuna as there are geologists investigating it.
And there are a lot of investigators.
Interest in this supercontinent has been intense ever since Rogers and Santosh, as well as Zhao et al., first described it in papers published early in the 21st century. (Meert; Meert and Santosh; Nance et al., 2014)
Why all the attention?
For one thing, everything came together for researchers right around then.
As I understand it, the supercomputing power needed to number-crunch a supercontinent into a model first became widely available in the 00’s.
Also around this time, pioneering isotopic studies began to pull new data out of Precambrian rocks, including but not limited to what one researcher in the NOVA video calls biosignatures.
Besides having better tools and more data, researchers have excellent reasons to work on supercontinents, particularly the granddaddy of them all, Columbia/Nuna:
- Money and technology. As people in both industry and science know, the enormous geological forces associated with supercontinent construction and destruction are also very good at concentrating lots of economic ore in rock formations — everything from gold and silver to the rare earth elements used in your computer equipment. (Ernst et al., 2013; Huston et al.; Pehrsson et al.)
In the Black Hills, it was gold, leading to a late 19th-century gold rush for European-Americans and tragedy and loss for the Lakota living there, as well as for many whites, including General G. A. Custer. (More information.)
- Planetary firsts: Back in the day, Proterozoic Trans-Hudson Mountains were a big deal in every sense: Himalayan in stature, as well as involved with geological developments like the first known opening/closure cycle of an ocean – the Manikewan – and final assembly of Columbia/Nuna, the planet’s first true supercontinent. (Corrigan et al.; Evans and Mitchell; Palin and Santosh; Rogers and Santosh, 2009)
The start of plate tectonics should be mentioned here as well, but that’s all I’m going to do in this post: mention it. We can get into more detail on that vital but Earth-sized and controversial matter next time.
After all, we still haven’t yet gotten to the second big effect biology has on geology. Let’s finish that story first.
- Connections (probably): I’ve learned that anyone who tries to track down other firsts — such as eukaryotes (every form of life that isn’t bacteria or an extremophile); plate tectonics; oxygenation of oceans and atmosphere (which probably helped along the evolution of multicellularity and ancestral animals) — keeps running into Columbia/Nuna in a variety of important but highly technical ways.
That can’t be a coincidence. But as we’ve seen, unequivocal explanations for it are hard to come by.
Columbia/Nuna is pretty much a blank wall.
Sure, there’s enough data preserved in rocks to show that this supercontinent’s assembly, reign, and breakup coincided with major changes in life’s evolution and in Earth systems. (Reddy and Evans)
But that’s about it. There isn’t enough direct evidence left to give researchers 2-billion-year-old details on the possible relationships.
It doesn’t help that, geologically speaking, Earth was, in some ways, an alien planet back then.
But it’s okay. Biology was up to something in the early Precambrian that not only took care of these differences – somehow – but is also still very much a thriving business today.
Are you uniformitarian?
Columbia/Nuna is so old that geologists can’t totally rely on their handy rule declaring that the present is the key to the past. (Diamond et al.; Morton; Stern and Miller, 2021)
This go-to approach of theirs is called Uniformitarianism. It is the common-sense recognition that, whatever Earth is doing today, it has been doing for a long, long time.
This is reasonable: events on Earth and other rocky worlds are quite repetitive.
Here, for example, time passes; winds blow; there is rain, snow, drought; glaciers form and melt away; sediments accumulate in low spots; rivers run down to the sea; tides come in and go out; ocean waves roll onto shores; continents drift; volcanoes are born, erupt for a while, and then die; mountains rise, weather down, and then appear again in new forms.
Over and over and over…
Once you know what to look for, you can often see the tracks of these and other ancient geological occurrences recorded in stone and figure out what might have happened.
Of course, there are one-of-a-kind exceptions, like the big bolide 66 million years ago at the end of the Cretaceous period.
Many uniformitarians rejected that explanation for the end-Cretaceous mass extinction at first.
But few impacts, as far as we know, have had such global effects. Even with biggies like Chicxulub, the same Earth-system patterns, recorded in stone, picked up again after the dust settled.
Pages of this repetitious Terran epic may break apart over time, getting scattered, deformed, or lost. That’s okay; geologists are incredibly good at puzzles.
Uniformitarianism only fails them when the geology they’re investigating originally formed in circumstances unlike those of our world today — on the planet Venus, for instance, which is closer to the Sun than we are and therefore hotter. (Foley and Driscoll)
Not unlike the fiery hellscape of Darth Vader's favorite getaway, Mustafar, this image of the surface of Venus taken by @NASA's Magellan spacecraft shows extensive lava flows that streamed from the base of Maat Mons. 🌋 #StarWarsDay 1/2 pic.twitter.com/OJ6MIOLV6v
— NASA History Office (@NASAhistory) May 4, 2022
Or on early Precambrian Earth.
No one is sure exactly how strange the Hadean, Archean, and early Proterozoic eons were, compared to our own Phanerozoic.
But experts agree that it was a very different time.
Something new, something negative
As I understand it, the biggest problem facing researchers isn’t obvious Precambrian weirdness like possible Earth-ripping lunar tides on a planet that, in the Hadean, was spinning so fast, one day and night might have only taken six hours (Klatt et al.; Sleep, 2010) —
— or that ghastly Hadean/early Archean greenhouse atmosphere of hydrogen sulfide, cyanide, carbon monoxide, carbon dioxide, methane, and water vapor (Hsia et al.) —
— or the oceans rich in dissolved iron, with perhaps a touch of sulfur near the surface. (Hoffman et al.; Kharecha et al.; Reddy and Evans)
The biggest problem appears to be the fact that young Earth was breaking the law.
Matter mixes, water flows downhill and wood burns into ashes. If nothing else were to take place, sooner or later all matter would end up in a uniform mix of everything, water would collect in the world’s oceans and all biomass would be burnt to ashes. All processes would lead to a ‘dead’ Earth state with no gradients present to drive fluxes and no free energy available to run life…The three examples are processes that are undoable, or technically speaking, they are irreversible…Specifically, this is what the second law of thermodynamics tells us.
— Axel Kleidon (see source list)
Obviously Earth didn’t die as the Trans-Hudson Mountains and other parts of Columbia-Nuna weathered away.
But it should have. In fact, our planet should have been ‘dead’ long before that, canceling the supercontinent before its construction even began.
Instead, things like this are happening on Earth all the time:
According to Axel Kleidon and some others, photosynthesis uses up solar energy to indirectly power wildebeest, cheetah, the aircraft filming this chase, and those watching it – as well as Earth systems!
It’s physics we’re talking about, not the social contract: the law of gravity, for example, is not and never will be a suggestion.
Earth must follow the same physical laws as Mars and other rocky worlds.
But Kleidon and others define (jargon alert) the second law of thermodynamics in ways that show the Second Law is broad enough to allow for cheetahs and wildebeest and you and me.
Biology’s other important effect on geology
As I understand Kleidon, that hypothetical “‘dead’ Earth state” he mentioned earlier happens because of “entropy.”
This sounds deep, but Geotime Ginger and the rest of us are not into “deep.”
Fortunately, basics are very simple: when there’s lots of entropy around, no hills exist to be climbed and no energy is available to climb them.
The math is atrocious, but Kleidon also puts it in fairly clear language:
…the second law of thermodynamics [uses] entropy as a measure for the lack of gradients and free energy…matter is well mixed and no free energy is available to perform physical work or run chemical reactions.
This will probably make physicists and mathematicians weep, but it seems to me that, if entropy means that there are no gradients to climb and no free energy around to do the work of climbing, then our lively Earth must have a negative balance at the entropy bank keeping us out of equilibrium.
To sum up what I understand of it, our planet gets lots of radiative energy through space from the Sun – a “credit balance,” so to speak. But we’re living on it (organizing and building complex stuff) instead of paying off our “balance” (radiating anything close to the same amount of energy back into space).
This, despite it being a law of thermodynamics that we’re talking about here and our planet’s core being as hot as the Sun’s surface. (Oppenheimer)
Kleidon blames our negative “account balance” on the green stuff – but he’s not talking about money.
Solar radiation…provides the photochemical energy to drive photosynthesis, which in turn provides the major source of free energy to drive geochemical cycles within the Earth system…
I get plants → wildebeest → cheetahs. But there’s just so much math involved in the bigger picture! I’ll take Kleidon’s word for it that photosynthesis indirectly drives all these systems.
That’s the other big effect biology has on geology here on planet Earth, and it’s a doozy!
If I understand this school of thought right, all of the amazing world that’s constantly in motion outside our windows, around us, and within us today – ever changing yet always staying within Earth’ overall pattern of repetition – all this works because photosynthesis gives us a negative balance at the entropy bank!
And photosynthesis, while probably not as old as life, has been operating a long
time. (Blankenship; Sleep et al.)
Some researchers recognize evidence of sulfur- and iron-based photosynthesis in 3.8-billion-year-old Greenland shale. (Sleep, 2010)
There were no fish or other complex marine creatures in Archean or Proterozoic seas – the way evolution has gone, there couldn’t be fish, and therefore jawed vertebrates and eventually cats, until this initial stage of life was passed – but there were bacteria of various kinds, using sunlight to metabolize iron as well as sulfur. (Kharecha et al.; Sleep, 2010)
Remember – alien planet.
The sulfur was probably present in both air and ocean surface waters.
At that point, the depths were loaded with dissolved iron, and offshore winds from the supercontinent in the winter and spring would cause upwelling, bringing this nutrient into areas of the sea that sunlight could reach. (Kharecha et al.; Valentine and Moores)
Bacteria did their photosynthetic thing in sunlit shallow waters, including on the submerged edges of Archean cratons. (Ernst, 2009)
Later, after cyanobacteria had begun metabolizing H2O instead of iron or sulfur (unleashing oxygen as a byproduct), photosynthesis – and the continuing evolution of life – probably also went on in Columbia/Nuna’s rift zones, where geothermally heated, nutrient-rich water circulated through crustal rocks. (Huston et al.; Mulkidjanian et al.; Nance et al., 2014; Santosh, 2010, 2013)
Photosynthesis – the solar-powered work done for more than a billion years by creatures who, today, individually live some 12 hours on average (source) – not only supported Archean and Proterozoic life but also thermodynamically powered early Precambrian Earth’s systems.
Life, with its DNA “blueprints” and photosynthesis metabolism, keeping the planet thermally off balance…biology and geology, intermingling, ever changing almost since the get-go…
Well, to make a long story short (and to give you a break in case you’re hungering for some PB&J), right around the start of supercontinent Columbia’s reign, all of this led to, among other things, a new, much more complex biological domain: Eukarya. (Knoll, 2014; O’Donnell et al.; Reddy and Evans; Walters)
And cats are eukaryotes.
Okay, Little One:
Let’s end this post on that biological high point, taking up geology next time – things like that extremely hot planetary core, with a supercontinental lid sitting on top, as well as the surprising way Columbia/Nuna seems to have ended: by morphing into a new supercontinent: Rodinia.
Featured image: ajschwar/Pixabay, public domain)
Sources are lengthy, so they have their own page; since he is mentioned prominently though, here’s Kleidon:
Kleidon, A. 2010. A basic introduction to the thermodynamics of the Earth system far from equilibrium and maximum entropy production. Philosophical Transactions of the Royal Society B: Biological Sciences, 365(1545): 1303-1315. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2871909/
Note: There aren’t different text colors in this post due to circumstances beyond my control, but when this chapter goes into the book, “Hadean” will be red, “Archean” will be hot pink, Proterozoic references will be yellow, and references to Precambrian life will indeed be green, no matter how hard Geotime Ginger argues against it. 🙂
All of these wonderful cat graphics are by Rasulov/Shutterstock.