Why Was The United States Underwater?

Several months ago, I wrote about the fossil my son found and what it most likely was. What I didn’t talk about in either article was the trip we took to the Trammel Fossil Park here on the north side of Cincinnati. It’s really just the exposed rocky side of a hill, with signs posting the various stratigraphic layers so you know where you’re looking and other signs showing you the fossils you’re likely to find at each level. There’s no cost to go, and you’re allowed to keep any fossil-bearing stones you find that you care to haul down the hill and back to your car. I found some brachiopods.

My son was extremely disappointed with the trip, at least for the first ten or fifteen minutes we were there. We’d told him we were going fossil hunting, after all, and he wanted to find a Tyrannosaurus rex skeleton. Which, lets be honest, would have been extremely unlikely even if the park had exposed strata from the Albian. But he was six at the time, and he wanted a dinosaur. So I reminded him that the layers we were looking at were from an ocean, because Ohio was underwater at the time.

I don’t think he asked today’s question at that point, but it helped inspire it. Because, eventually, he asked me this: “Why was the United States underwater?”

Well? Why?

Uhm. Something to do with plate tectonics, I guess? And maybe changes in climate?

Can you do better than that?

Of course I can. This’d be a pretty lame blog post, otherwise.

What are plate tectonics?

That’s a great question, and to understand it we’ll need to cover the structure of the Earth itself. The Earth is comprised of multiple layers, rather like an onion. These layers are the:

  • Lithosphere: the outermost rocky shell of a rocky planet (our own, for instance).
  • Asthenosphere: the hot, viscous layer that the lithosphere floats on.
  • Mesosphere (or mantle). Geologists have an explanation for why this is distinct from the asthenosphere and the outer core, and it has something to do with temperature and pressure causing one type of mineral to decompose into another type of mineral. I didn’t quite follow the explanation, and I think I’ll save trying to understand it for the day when my son asks “what is the mesosphere?”
  • Outer Core, a sea of liquid iron and nickel.
  • Inner Core, an extremely hot ball of (mostly) iron and nickel kept solid by pressure.

The lithosphere is the layer we live on – the high parts are the continents and the lower parts are covered with water. And it isn’t a solid shell. It’s broken up into (depending on who you ask and the definitions they use) seven or eight major tectonic plates and a bunch of minor ones. And the plates move.

Why do they move?

The tectonic plates move because the Earth is hot.

Let’s start with an analogy. When you boil water, you get an uneven distribution of heat Heat rises, after all, but the source of the heat is at the bottom. So the hot water rises and the cool water sinks. But then the hot water at the surface cools and sinks, and the cool water at the bottom heats up and rises. This gives rise to something called convection currents. this effect isn’t limited to water, though. All liquids do it – our atmosphere, for instance (which functions a lot like a liquid).

The Earth, when you get below the lithosphere, is pretty much a liquid as well. The mesosphere has convection currents in it, and the tectonic plates can be thought of as the “cool water” part of the current in the boiling water analogy. Magma pushes up from the mesosphere into the lithosphere at the Ocean Ridge (a planet-circling chain of mid-ocean ridges), pushing and expanding the plates. The plates then sink back down towards the mesosphere at subduction zones. These currents also push around the solid chunks of the lithosphere, in much the same way that ice cubes floating in boiling water will be pushed and shoved around.

Now, even the “minor” tectonic plates are massive structures. So, when they get moving, there’s a lot of force built up. When they collide, something has to give. And frequently, what gives is the structure of the plate itself – it will buckle and crumple, throwing up mountain ranges and pushing parts of the plate below sea level. If water, in the form of the oceans, gets access to that portion of the plate below sea level, it will begin to fill the depression. That’s what happened in the theorized Zanclean Deluge, for instance. 5.33 million years ago, the Mediterranean was a depression in the Eurasian plate (bordered by the African and Arabian plates) that was below sea level. It had been a sea previously, until shifting plates cut off access to the Atlantic and the waters dried out. Then the plates shifted further, access to the Atlantic reopened, and the basin refilled in a period of approximately 2 years (with water gushing in at a flow rate 1,000 times greater than that of the Amazon River).

So. Plate tectonics is the answer?

Not completely.

Really? What else is there?

There’s changing climates. See, the Earth was – on average – a whole lot warmer back before the continents had moved into the form we’d recognize today. At present, our average global temperature is about 60 degrees Fahrenheit. During the Paleocene-Eocene Thermal Maximum (55-56 million years ago) the average got up to about 73 degrees F – there were no ice caps at the poles then, and there were palm trees and crocodiles above the attic circle.

Now, estimates are that if the ice caps melted then global sea levels would rise about 70 meters. So that’s not really enough to make an ocean out of (say) the Great Plains, although it would completely reshape the coast and drown Houston and New Orleans. But since the plates were buckled differently back then, the extra water would have increased the odds of flooding taking place.

But, ultimately, North America being underwater had far more to do with plate tectonics than changes in climate.

Oh, as a bonus, the Paleomap Project has a series of great maps of the Earth in different geologic epochs. Here’s what the Earth looked like during the age of the dinosaurs:

Yep.  It was a different world, back then.

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Who Is Your Favorite President Riding A Dinosaur?

“Dad?” my son asks, looking at me from the other end of the couch, “who’s your favorite president?”

I look up from my book. It’s out of nowhere, and pretty obviously a “dad, pay attention to me” kind of question, and it’s hit me out of left field. “Well, I don’t…” I start to say.

“Only he has to be riding a dinosaur!” my son adds. “And it can be any dinosaur you want, as long as it’s real!”

How on earth do you answer that?

We’re dying to find that out, really.

All right. So, clearly this is a two-part question. “Who is my favorite president?”, and then “what is my favorite dinosaur that someone could read?” How hard could this be?

The internet never fails to deliver

Who is your favorite president?

That… is a really good question. I could easily list my top two or three least favorite presidents, but I’ve never really thought about which one of them is my favorite. I will say I’ve got an unreasonable soft spot in my heart for Ronald Reagan, mostly because the 1978 Carter vs. Reagan election is the first one I really paid any attention to, and I was seven years old (the same age as my son), and my mom was a Reagan Republican and my dad was a Reagan Democrat. So, yeah. There was an influence there, because when you’re seven years old your parents are the smartest and best people in the whole planet.

My political views have shifted since I was seven. Still, it’s hard not to remember him fondly through the lens of childhood memory.

So, it’s Ronald Reagan?

I don’t think so, not really.  Despite that picture up there of him riding some variety of velociraptor.

Then who?

See, that’s tricky. It’s easy to look back in history, and see problems – often huge problems – with any or all of the presidents. They were, after all, human beings with an interest in becoming (arguably) the most powerful single man in the country (and, particularly in the late 20th century, the world). That sort of man tends to have a number of less-than-admirable characteristics. Particularly if you don’t agree with his policies.

But, clearly, I need to make a choice. So, after doing some thinking, I’ll go (this time, at least) with Lyndon B. Johnson because of the things he accomplished as president.

Lyndon B. Johnson?

Lyndon Johnson was the 36th president of the United States, born August 27, 1908 near Johnson City, Texas. He was elected to the House of Representatives in 1937, served in the Navy in World War II, and then was elected to the Senate in 1948 (becoming the Senate minority Leader in 1953, and then the Senate Majority Leader in 1954). He served as John F. Kennedy’s running mate in 1960, and became president on November 22, 1963 after President Kennedy was assassinated. As president, he ran again and was reelected with 61% of the popular vote.

What did he do, to earn the position of my current favorite president? Well, here’s what his bio on Whitehouse.gov says:

First he obtained enactment of the measures President Kennedy had been urging at the time of his death–a new civil rights bill and a tax cut. Next he urged the Nation “to build a great society, a place where the meaning of man’s life matches the marvels of man’s labor.” In 1964, Johnson won the Presidency with 61 percent of the vote and had the widest popular margin in American history–more than 15,000,000 votes.

The Great Society program became Johnson’s agenda for Congress in January 1965: aid to education, attack on disease, Medicare, urban renewal, beautification, conservation, development of depressed regions, a wide-scale fight against poverty, control and prevention of crime and delinquency, removal of obstacles to the right to vote. Congress, at times augmenting or amending, rapidly enacted Johnson’s recommendations. Millions of elderly people found succor through the 1965 Medicare amendment to the Social Security Act.

Johnson also signed the Outer Space Treaty in January 1967, banning the use of nuclear weapons in earth orbit, on the moon, on other planets, and in deep space. He further signed the Nuclear Non-proliferation Treaty in 1968, committing the US to a policy of prohibiting the transfer of nuclear weapons to other nations, and began the negotiations that returned the Panama Canal Zone to Panama.

Pretty awesome, in my opinion, but not perfect. He dragged out the Vietnam War as well, and sent US Marines into the Dominican Republic to support the leader of a coup against the leaders of a coup against the democratically elected president of that country, when the people of that country rose up against the leaders of the coup. Neither of those things were what you’d call good things, but any president you care to name will have similar blemishes on his record – with the possible exception of William Henry Harrison, who didn’t manage to serve long enough to do anything particularly bad. As president, at least.  So, at this time, I’ll say Johnson still did some pretty good things for the country and say he’s my (current) favorite.

Fair enough. Now, what about dinosaurs?

Microraptor!

This is even trickier, because I love dinosaurs. All of them. Fortunately, I can narrow the field a little. The question, after all, states that the president has to ride the dinosaur, so I can rule out something like microraptor. The four wings are pretty cool, but it’s the size of a smallish chicken. You’d need hundreds of the things pulling a chariot, and that loses something quickly.

Actually, I tell a lie. It’s not tricky in the slightest. Because, no matter what, my favorite dinosaur is and always has been the Tyrannosaurus Rex.

Ah. The Tyrant Lizard King.

Oh, yeah.

Tyrannosaurus was always my favorite, from an early age. I mean, sure. I liked Triceratops and Stegosaurus as well, and I love some of the new dinosaurs that have been found over the past few decades, and Deinonychus caught my attention because my very first ever issue of National Geographic had a big article about the fossils of that brand new (to me, at least) dinosaur. But, at the end of the day, the idea of being a massive bipedal carnivore named the Tyrant Lizard King was awesome to my youthful mind and that feeling has never gone away.

Tell us about it.

Tyrannosaurus rex, based on recovered specimens, was a massive bipedal carnivore. Like, 12.3 meters (40 feet) long, 3.66 meters (12 feet) tall at the hips, and anywhere from 8.4 to 14 metric tons in weight. It was one of the largest land predators ever, and most paleontologists agree that it was an active predator that – like modern active predators – wouldn’t turn down the opportunity to chase other animals away from carrion and chow down as well. Their skulls are nearly as long as I am tall (I’m 6′ 5′ and their skulls were 5 feet long), and their teeth were foot long “lethal bananas”.

Well, maybe not every single tooth. But they still had some giant teeth.

They probably had feathers as well.

“I’m an utterly FABULOUS Tyrant Lizard King, baby!”

Yes, yes, I’m aware of the recent paper in Biology Letters (Tyrannosauroid integument reveals conflicting patterns of gigantism and feather evolution), indicating that they had scaly skin.  Early tyrannosauroids did have feathers, but the abstract states that “extensive feather coverings observed in some early tyrannosauroids were lost by the Albian”(the Albian being a stratigraphic layer and a period of time roughly 113 to 100 million years ago).  So, it’s unlikely at this point that T. rex was that fabulously fluffy thing in the image above, but the Smithsonian article on the paper (since the paper itself is paywalled) states that the authors indicate that T. rex still had plumage on it’s back.  Much more punk than New Wave, in other words. Still, I like to imagine them as 12 meter birds of paradise – which tells you everything you need to know about the way my mind works.

Which means..?

In answer to my son’s question, let’s saddle up Lyndon B. Johnson on a fabulous black and electric blue feathered Tyrannosaurus rex and do an elaborate ritual dance to celebrate the passage of the Civil Rights Act.

What Fossils Did I Find?

Way back in February, I wrote about the fossils my son found. At that time, I promised him I’d do some research and find out what kind of fossils they were. To recap, here’s what they looked like:

Time passed, and he asked other questions, and I got busy studying for a certification test at work (which is why I’ve been so quiet the past few months). But finally, since I’ve had a chance to catch my breath, it’s time to answer a question: what, exactly, are those fossils?

Well?

My primary source for this is Identification Guide for Common Fossils of the Cincinnatian. Based on this guide, most of the fossils appear to be Brachiopods, most likely some species of Cincinnetina (since they’re common in the region) – from the pictures in the guide, though, they could be Platystrophia ponderosa. The point is, they’re certainly brachiopods, and they’re around 480 to 440 million years old.

To tell you the truth, my son was disappointed that he didn’t find a Tyrannosaurus Rex.  That wouldn’t be particularly likely, however, for a few reasons.  The first being that T. Rex didn’t live 440 million years ago, and the second being that if T. Rex did live 440 million years ago in Cincinnati he would have drowned.  Because Cincinnati was under water.

Map courtesy of The Paleomap Project

So, no Tyrannosaurs here.  Certainly not in the strata that was laid down on his brachiopods.

And what, exactly, is a brachiopod?

Well, Wikipedia says that brachiopods are:

…a group of lophotrochozoan animals that have hard “valves” (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection.

“Lophotrochozoan” animals are a clade of bilaterally symmetrical animals with cillia around their middle, if that helps.

Brachiopods are related to mollusks and annelid worms (earthworms and leeches). There are around 330 living species. There were a whole lot more of them back in the past, with the greatest diversity of Brachiopods occurring in the Devonian. The Permo-Triassic mass extinction crushed a lot of that diversity, and it has never fully recovered.

Modern brachiopods feed by sucking water in through their sides, using their cilia to trap particles of food, and then expelling the water and any waste products through the front. They absorb oxygen through their skin, and have colorless blood, and some modern species can live over 30 years (assuming they aren’t eaten).

Case closed, right?

Well, except for this strange little thing:

Uhm. What is that?

I have no idea. I’m pretty sure that’s not a brachiopod. Not unless we’ve got the shell end-on, and it also folded in a pretty dramatic fashion. After some digging, I four possible candidates. Here they are.

1. It’s just a rock. Needless to say, I find that boring. It is the null hypothesis, but I don’t think it’s accurate. after all, the color resembles that of the other fossils in the piece of stone my son found. So, although it’s certainly possible, I don’t think it’s correct.

2. It’s a piece of an Isorophus cincinnatiensis. This might be a reach, because it would make it a fragment of an arm of a 440 million year old echinoderm. Pros for the argument are that it’s from the region, it’s about the right size, and it looks kind of like the arm seen in this picture. Cons for the argument include the fact that it doesn’t look a whole lot like the arm in that picture.

3. It’s a bit of coral. I couldn’t find any pictures of coral that curves like that, but that doesn’t mean they don’t exist.

4. It’s something I can’t identify. Yes, yes, that’s an utterly lame hypothesis. But I’ve got nothing else, and I’m pretty sure it’s some flavor of fossil. So, I’ll probably just leave it at that. Unless someone reading this happens to know what that might be.

What Is A Fossil?

A couple of days ago the weather was nice enough that I walked to my son’s kindergarten to pick him up. As we walked home, he declared that he was “collecting nature” and picked stuff up. Pine cones (which he rejected after a minute as being “squishy”) and sticks, things like that. Oh, and a rock. He picked up a largish, flat rock that got him asking if we could eat off a stone one day. “People used to do that,” he assured me. “Can we?”

“Maybe,” I told him, turning the stone over in my hands. He’d asked me to carry it, so he could climb a retaining wall. “But we’ll have to clean it well first.” Then something caught my eye. “Hey, look,” I said. “Fossils!”


His eyes went big, and he scrambled over to see what I was talking about. Impressions of shells in the stone. “My first fossil!” he declared, taking the stone back. “I found my first fossil!” And suddenly, he had to carry the stone, and he told me he wanted to get a paint brush out.

“Why?” I asked, puzzled.

“That’s what paleontologists use to clean stones!” he told me.

At the end, we settled on using an old toothbrush of his to scrub the dirt away. And that is how we found the thing that will be at least two entries for this blog.

What is a fossil?

If you’re reading a blog like this, you probably have a passing familiarity with what a fossil is. If nothing else, you’ll be thinking about dinosaur bones that have turned to stone and then been dug up and assembled to display in a museum. A fairly succinct definition of the word comes from Biology Online, which states:

noun, plural: fossils

(1) Any preserved evidence of life from a past geological age, such as the impressions and remains of organisms embedded in stratified rocks.

(2) The mineralized remains of an animal or plant.

adjective

Having the characteristic, or pertaining to the nature, of a fossil.

Supplement

Fossils include shells, imprints, burrows, coprolites and organically-produced chemicals. The oldest fossils were bacteria that existed 3.8 billion years old. Fossils are once thought of to be all from extinct species until some were found to belong to species that are still living.

Word origin: from Latin fossilus, (something dug up)

In other words, fossils aren’t just bones, and they aren’t even necessarily pieces of living things. The Sam Noble Museum in Oklahoma follows what appears to be a common practice of breaking fossils into three broad categories: body fossils, molds and casts, and trace fossils.

  • Body Fossils are what you usually think of when you think of a fossil, the fossilized remains of an organism (or part of an organism). Usually, it’s just the bones or other hard parts of the animal because the soft tissues rot and/or get eaten.
  • Molds and casts are a type of body fossil, but they aren’t directly the remains of the organism. A mold is rock that has formed around the body fossil, making an imprint of the fossil’s shape. A cast is what you get if new rock forms in that mold, or more commonly if sand or mud fills the inside of a hollow structure (such as a shell) and becomes rock. Interestingly, sometimes you get molds of the soft tissues of the dead animal. When found, these allow insight into what the animal’s skin was like.
  • Trace fossils are indirect signs of a creature, such as footprints or coprolites (fossilized waste) or burrows or nests.

How Do Fossils Form?

I’ll be honest, and tell you right here and now that I’d assumed that there was a whopping one single way that fossils form. The classic “bones get covered and minerals slowly leach into them over time, replacing the calcium in the bone” routine you probably learned about in elementary school (or, if you’re like me, from reading a ton of dinosaur books in kindergarten). This is certainly one way to do it, but it isn’t the only way. The most common methods are petrification and carbonization, but there are most certainly others.

Petrification is the most common variety of fossilization, and (as you might guess) it’s the classic “bone or shell to stone” form of fossilization. It comes in at least two forms, replacement and permineralization.
replacemnet-fossil-galleryimage

  • Replacement is the best known of the best known methods, because it’s the one you always hear about. Water dissolves the original hard structures, replacing them with different mineral matter. What kind of mineral matter depends on the mineral content of the water, but calcite, silica, pyrite, and hematite are most common.
  • Permineralization happens when ground water infiltrates microscopic pores and cavities in the hard structure, depositing minerals. This results in a fossil that still has much of the original hard material left behind, mingled with the deposited mineral.

Carbonization is a form of fossilization most commonly found in plants, although animal can do it as well. Under the right conditions the organic substances of the organism decay but the carbon in the organic molecules is left behind in the shape of the fossilized structure.
carbonized-fossil

There’s also a few types of fossil that you might not think of as “fossils”, because they don’t turn to stone. Plants and animals trapped in amber are fossils, for instance. So are the animals that got trapped in tar pits (La Brea being the famous example here in the United States), and the animals that froze and then freeze-dried in the Arctic (such as mammoths). They’re still preserved evidence of life, even though they didn’t turn to stone.

So, that’s a really high level look at fossils. Tune in next time, when we try to work out what fossils he has. Because trust me, my son has been asking.