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Remember: scientists love it when the impossible happens. (At least when the impossible happens in an observable, empirical fashion.) It’s time for us to rethink our understanding of the process of fossilization. As we understand it now, this would have been impossible – but it happened! So now we need to work out the how and why. This is so COOL!

And here it is – soft tissue found with a 70 million year old fossilized dinosaur bone! A T-rex bone, to be precise. This is beyond cool. It means that they can do some biological comparisons between the Big T and birds, and they may even be able to sequence its DNA. Don’t worry, there’s a BIG difference between knowing an animal’s DNA and being able to clone it, so we won’t be seeing Jurassic (or in this case Cretaceous) park any time soon.

Scientists recover T-Rex soft tissue.

Yep, the space shuttle. And yet, it must be geology related – I’m writing about it, aren’t I?

There’s a nifty piece over at the Planetary Society blog about the Shuttle Radar Topography Mission. Basically, they got near-global topographical maps of the Earth out of this – more detailed than ever before!

Topography is very important to geology. It helps you figure out what’s lurking beneath the surface, and what forces might have acted to create the surface in the first place!

There’s a bunch of nifty links at the bottom of the article, which point to several specific pages of what they’ve figured out with the data. I suggest looking at the one about the rift valley in Tanzania and Mount St. Helens, since both are near and dear to my heart. But all of the information is way cool. (And some, like the information about New Orleans and its flood, is way important too.)

Ready for some geology humor? Of course you are!

While doing my mineralogy homework today, I discovered that there’s a fun mineral, called Realgar. It’s very pretty, which deep red, prismatic crystals. (Prismatic means that it forms with very flat surfaces.)

Realgar is Arsenic Sulfide. Which, if you know your periodic table, you’ll be way ahead of me here…

AsS!

Yes, that’s the chemical formula. I got a geeky giggle out of that.

Go here if you’d like to find out more about crystalline AsS! It’s actually a lot prettier than you’d think.

I’ve got another geeky geology joke to tell you, but for now, I’d better get back to my homework.

Just a short one – I’m still alive, I swear. School just started, which is very exciting. I’m taking Mineralogy, which thus far has been a very exciting class. We’re doing “Adopt a mineral” where we pick out a mineral at the start of class, and write a paper about it at the end. Mine is a variety of Olivine, which is a very neat mineral, so expect to hear more about it in the future.

I’m rushed right now, though, so just a quick one.

Today we were talking about physical properties (more on that later), and my professor brought out a piece of a meteorite to pass around. It had been cut neatly from the main body of the meteorite. So one surface was polished to a dark, metallic shine, and the other side was all whorls and bumps, rough and rusty black. It was a lot heavier than I expected – iron and nickel with just a few traces of other minerals.

That piece of meteorite was 4.5 billion years old, which makes it older than the oldest rock discovered thus far on the earth. (Which is a piece of metamorphic rock that is, I believe 4.4 billion years old.) And this rock had hurtled through space, across unknown, cast distances, and then torn its way through our atmosphere to impact in Africa.

As I looked at the rough side of the rock slice, I felt true awe. What kind of story could a rock tell, of 4.5 billion years. Where had it been. Even trying to imagine that sort of antiquity is impossible for the human mind, really. We can only grasp numbers up to a certain point, and then it just becomes more than we can understand.

This is why I think geology is so exciting. If you believe in a god, of whatever sort, this is what it’s like to reach out and try to touch it.

No, it’s not about poor explorers wandering across a featurless plain of snow, searching for the South Pole so they can have bragging rights to go with their frostbite when they get home.

I’ve been wanting to write about this for a while, just because it’s so cool!

It starts out very simply. There’s a mineral, called Magnetite. As the name indicates, it is magnetic, and naturally so. In fact it’s the most magnetic mineral on the planet. If you’ve ever heard of lodestones – which were used to make the earliest compasses – those are actually pieces of magnetite. Magnetite is an important source of iron ore, and is also used to “blue” steel to prevent it from rusting.

Magnetite can form in significant amounts, but more importantly, it’s present in at least small amounts in almost all igneous rocks. Igneous rocks (in case you don’t remember from grade school, which is the last time most of us had geology) are the ones that form directly from molten rock. They flow and explode from volcanoes, but also cool slowly beneath the surface of the earth in upwellings of magma from the mantle. There are a lot of igneous rocks in the world, and they’re pretty durable. This means that there are a lot of igneous rocks around for us to look at, and some of them are billions of years old.

Igneous rock forms when magma (or lava, which is what we call magma when it’s on the surface) cools completely. As the melted rock cools, all of the different minerals that have been mixed together in it start to group up and form crystals. If you’ve ever seen sugar crystals “grown” when you put a stick in a glass of sugary water, it’s exactly the same idea. At that point, they’re fixed in place and don’t change position until the rock is destroyed by either being melted again (geologic recycling!) or eroded away.

Okay, so what does any of this have to do with Polar Wandering… whatever that is.

Because Magnetite is magnetic, when it crystalizes, it points toward the magnetic north pole. And once it is crystalized, it can’t move. So you can look at it as a record, a photo of a little finger pointing north, indellibly etched with the date and time. At this moment in history, north was this way.

All very well and good, but north has always been north, right? So who cares?

Well, what if I told you that north hasn’t always been north? Oho!

Once we (meaning geologists) were able to examine the little crystals of magnetite to see what direction they were pointing, we discovered something very strange. In the different layers of igneous rock, the little bits of magnetite had a serious disagreement over which direction was north. Now, keep in mind that when you have different layers of rock, that means different ages of rock. The oldest ones are at the bottom, and then they get younger as you move toward the surface.

So, for example:

Rock layer #1 (the youngest) said that north was this way: /
Rock layer #2 (the middle) said that north was this way: |
Rock layer #3 (the oldest) said that north was this way: —
Well, how does that work? Magnetite doesn’t lie. When those crystals formed, they really did point toward north. After a lot of head scratching, the first thought was that maybe the magnetic north pole has moved over time, wandering across the surface of the Earth. (Whence, polar wandering, which can be plotted as a curved line across the planet.) It sounds kind of weird, but there had to be some explanation for what we’d seen. And science is very much about observing strange things in nature and then figuring out what might have caused them.

But then things got even weirder. We looked at magnetite from a different place – and entirely different continent. If the magnetic north pole had really gone meandering across the Earth, then the magnetite on that continent would agree.

Only… it didn’t.

We found rocks that were the same age as the first ones we looked at, and the little bits of magnetite helpfully pointed out that north was in a completely different direction from what the other ones said. And then we went to another continent and got a third set of answers that were different from the first two. And so on, and so on.

We sat back and scratched out heads. Every continent had a different path for the north pole to have wandered down throughout history. Did that mean that in the past, every continent had its very own north pole? That sounds pretty silly to begin with, and, well, right now we’ve obviously got only one north pole. The way the world works hasn’t suddenly changed just because humans discovered how to make compasses.

But… what if the continents themselves had moved? North had stayed the same (except of course when it switched places with the south pole, but that’s a subject for a different post) but the continents had wandered across the face of the planet, drifting and rotating.

That was the only explanation we had that fit the facts and followed the main principle of modern geology – that the geological forces and events that we see today are the same ones that shaped the world in the past.

Polar wandering is one of the strongest pieces of evidence for the theory of continental drift – the theory of plate tectonics. And since the time that scientists decided that having a multitude of wandering north poles was just plain silly, more evidence has been found to support the idea of continental drift. Today, we have satellites and other machines that can measure things so precisely that we can see the continents move. Some of them move as fast as six centimeters in a single year. To us, that sounds horribly slow, but think how much movement that adds up to in a billion years.

The ground beneath your feet is moving. We drift slowly across a sea of molten rock, even as the Earth spins out its days and rockets around the sun.

Now, how cool is that?

Wow, things are busy busy! This is what I get for deciding to take both Chem I and Calculus I in the summer. Oh well, if I manage to survive the next two months, I’ll be in good shape. I wanted to share this, though, because the picture is just so cool!

Ash Plume from Cleveland Volcano

Nope, not Cleveland Ohio. Cleveland volcano sits on the western half of Chuginadak Island in the Aleutian Islands. The picture was taken from the International Space Station, and it is amazing.

Make no mistake, this ash plume is really very minor in the grand scale of these volcanoes. The Aleutian Islands are very volcanically active, as they sit on the rim of the Ring of Fire. The Ring of Fire is the border of the Pacific oceanic tectonic plate, where it’s being ground under the surrounding continental plates. I’ll explain how and why this works later, when I have more time.

Anyway, the view from the top here is just amazing, so take a look! And thank you, NASA, for making pictures like this available!

Giant things that explode! It doesn’t get better than this.

The Discovery Channel has a great article about the magma plume under the Yellowstone Caldera.

This is some way, way cool stuff for several reasons, but let’s start with the basics. I love volcanoes. So far, they are my number one favorite thing in geology. Because, as said above, it just doesn’t get any better than giant things that explode.

Most of us are used to imagining classic Composite volcanoes, like Mount St. Helens in Washington state or Mount Fuji of Japan, well known for its presence in a multitude of paintings and wood cuts. Composite volcanoes look like ordinary mountains, normally with a crater on top, and they go boom in a very explosive manner. I’ll write more about composite volcanoes and why they like to explode at a later time.

The other really common type of volcano that you might be familiar with are shield volcanoes. Shield volcanoes are much, much bigger than composite volcanoes – in fact, they are the biggest volcanoes not just in the world, but in our solar system. (Olympus Mons on Mars is a shield volcano.) Instead of having steep slopes and that classic mountain shape, they’re more like gentle domes. Imagine a round shield, like the kind you see in mosaics of Greek warriors. Lay that shield flat on the floor, and you get the general shape of these volcanoes. Shield volcanoes are another thing I’d like to write about some time. They don’t explode like their smaller composite cousins, but they’re very active. And, after all, the Hawaiian Islands are all shield volcanoes (though most of them are inactive now) so it’s geology in action!

The kind of volcano I want to talk about now is in a category by itself, though. I’ve heard them called Caldera Volcanoes (which is a little misleading, and I’ll explain why), Supercaldera Volcanoes, Super Volcanoes, and VEI-8 Volcanoes. Whatever you want to call them, they’re massive. VEI-8 is probably the most scientifically correct way to classify them.

VEI stands for the “Volcanic Explosivity Index” – yes, it’s a classification of how big the boom is when the volcano erupts – and 8 is as high as it goes. A VEI-8 volcano dumps out at least 1000 cubic kilometers of of gas, ash, and lava. Just to give you an idea of how big we’re talking here, in 1980 when Mount St. Helens erupted (blowing one entire side of the mountain off in the process), its output was a mere 1.2 cubic kilometers. (Just as a note, 1980 eruption in question was VEI-5; VEI is an exponential scale, just like the Richter Scale is for earthquakes, which means VEI-8 is at least 1000 times more powerful than VEI-5.) This is the sort of eruption that will mess up the world climate for years to come, as well as devestate everything near it.

So what does this have to do with Yellowstone?

The big valley that makes up most of Yellowstone National Park is actually the caldera of one of these VEI-8/Super Volcanoes. There are actually several of these super massive (but thankfully defunct!) volcanoes in the United States. Yellowstone is the one we’re interest in, however.

A caldera is formed when a volcano collapses in on itself. Most volcanoes have a crater at their summit – or even several, if the volcano is really big, like some of the shield volcanoes. A caldera is much, much larger than these craters. If you make a cone out of paper and cut just the very end off, that would be a volcanic crater. If you cut the cone in half, the new opening would be like a volcanic caldera.

Sometimes volcanoes collapse slowly, due to subsidence. But sometimes the collapse occurs during an eruption or series of eruptions. This makes the eruption far more explosive and dangerous as enormous amounts of solid rock go crashing down into the magma within the volcano. Imagine having a bowl filled entirely with water. If you dropped a handful of rocks into it, the water would explode out everywhere. It’s the same idea, but even more powerful – because in the volcano, all of the magam is already under a lot of pressure.

So, when you come down to it, any volcano can have a caldera. All it has to do is collapse in on itself. But to give you an idea of relative size, a recent caldera formation occured at Mount Pinatubo in the Phillipines when it erupted (at VEI-6) in 1991. Mount Pinatubo’s caldera is 2.5 kilometers wide. The Yellowstone Caldera is 55 kilometers by 72 kilometers.

This all adds up to a HUGE picture of Yellowstone.

Most volcanoes in the world sit on some kind of tectonic plate boundary. (Mount St. Helens sits where the Pacific plate is ground under the North American plate.) In some cases, though, aren’t on these plate boundaries. They sit on top of mantle plumes, which feed them magma. A mantle plume is like a gigantic bubble of molten rock that rises up from the mantle, heading toward the surface. The Hawaiian Islands are fed by a mantle plume. The article that I linked to at the beginning of this is talking about the mantle plume that feeds Yellowstone. The heat from it feeds the geysers and hot springs.

The good news is that the last time the Yellowstone Caldera hasn’t erupted with that big, VEI-8 boom in the last 640,000 years. Every 20,000 years ago, it’ll have a little steam eruption (little being a relative term – the one that occured about 13,000 years ago left a crater in the caldera 5 kilometers across!), and it’ll have non-explosive lava flows on occasion. The most recent of these occured 70,000 years ago. So don’t worry, the giant that sleeps beneath Yellowstone shows no signs of waking.

I’ve never been to Yellowstone National Park, myself. The family vacations I went on never took us in that direction. Some day I want to go there, though, to camp and explore. And when I go, I’ll be walking across the mouth of an ancient, sleeping volcano. That somehow makes it all the more beautiful.