Geology of the National Parks

GeoMations and GeoClips


This week's lone GeoMation features Dr. Alley's visualization of the evolutionary process. Two additional GeoClips discuss "Ancient Bees" and "Extracting Fossils." Hope these add some insight into your Unit 11!


Evolutionary Process

Evolutionary Process
Click Here for Transcript of Evolutionary Process Video

Sometime about 3.8 billion years ago, life appears. And it starts coming up. There's new kinds appear. There's evolution going on. There's splitting of the types of things that are alive. And each of these lines represents a lineage. It's a living type, something that's alive in the world.

Now we know that about 570 million years ago, as oxygen is rising, as big critters are appearing, as shells appear, that there's this great diversification giving rise to lots of different kinds of life, which we call the Cambrian explosion. We find more and more types coming up. Each new living thing can give rise to other ones. And there's always some extinction going on, and so some of these lines don't come up to the today.

But there's quite a variety of life. Land plants appear. Land animals appear. And then we see this hideous mass extinction at the end of the Paleozoic, when most of the things on Earth died, probably because a really hot stagnant ocean is belching out poison gases that are really nasty. There's still a little debate on that.

We know that just a few things managed to get through that, and that they then are spreading, giving rise to new species in the new world. Because all the big critters were gone, there's room now for diversification. You get dinosaurs appearing and the other interesting things.

The dinosaurs are actually doing very well. They're flourishing. They are the big critters. Mammals are around, but they can't beat the dinosaurs. And then the meteorite does, so you get the great mass extinction at the end of the Mesozoic. And just a few kinds, again, succeed in getting through.

Those few kinds that manage to get through again give rise to diversity. There's space for splitting, for new types to appear. And so over 10s of millions of years, we see the rise of diversity and the things coming up to today. And so the world goes back to being a very rich, very diverse place, again with some level of natural extinction, but with a lot of splitting going on, a lot of types getting up to today.

Now, a couple of things that you may want to notice. One is that there's different types, that you come over here and you'd see something that might be mammals, or it be some subset of mammals like bears, and they will seem to be very different from some other type. And that difference arises because the split that gave rise to those types is actually way the heck down here.

And you can follow one type up to here, and you can follow the other type on up over here. And so because they came so far down in time that they split, you'll find that they look like very different types today. The other thing to notice, there's a reasonable chance that today, as we see marked right there, today may be the next mass extinction if we don't change our behavior.

Credit: Dr. Richard Alley


The fossil record includes some amazing things. If there were trees and insects far back in time, wouldn't you expect that the insects would have burrowed into the trees then as they do now? And wouldn't you expect that a tree with some of those burrows would be fossilized? Well, here is one example. Park Paleontologist William Parker of the Petrified Forest National Park explains fossil burrows to the CAUSE team.

Ancient Bee's Nests / Petrified Forest National Park

Ancient Bee's Nests, Petrified Forest National Park
Click Here for Transcript of Ancient Bee's Nests, Petrified Forest National Park Video


What you'll find in here, too, is you'll actually find insect traces, where they were underneath the bark, burrowing in just like modern ones do. This log, they call it the discovery log. This is actually a pretty important discovery.

What you're looking at here are insect traces and actual nest-- like little capsules here. You can see they're lined up. Little capsules of some nests of some kind of insect that actually lived in this log. You can see them here and here, coming out.

Now, these have been interpreted to be bees' nests. And if that's true, these would be the earliest record of bees by about 130 million years. Some entomologists disagree and say that this is very similar to some of the traces that modern beetles make, rather than bees.

But what they did is, some of these capsules in here, they went in and they found some preserved resins. And they actually tested them for geochemically, and they found the chemical that bees secrete. So some more work needs to be done on these to verify these results. But they were definitely made by some kind of insect. And it's a great example of how insects lived in these logs and used them as a food source and as a home.


Credit: Dr. Richard Alley

Petrified Forest National Park is best-known for trees turned to stone, but also has an immense wealth of fossils of various types from the late Triassic (in the Mesozoic, about 210 million years ago). Here, Park Paleontologist William Parker and assistant Randall Irmis explain to the CAUSE class the paleontological excavation of plates of the armored amphibian known either as Koskinonodon or Buettneria.

Uncovering Fossils / Petrified Forest National Park

Uncovering Fossils, Petrified Forest National Park
Click Here for Transcript of Uncovering Fossils, Petrified Forest National Park Video

We're heading into one of the famous locality areas at for paleontology at the Park.

Volcanic ash? Is that what you just said?


There is volcanic ash here.

It is. It's volcanic ash.

There's a big hole. See, so a lot of times when we find the bones, this is what you'll find. There's an accumulation, and it's rolled down the hill. And this is what happens to the bones when they sit on the surface for a long period of time. They basically break apart into smaller and smaller fragments, and at a point in time, it becomes impossible to put them back together. So all the bones at the bottom of the hill have basically come from these bones here.

So what we do is we dig in, and we see if we can uncover them. These little tools, like dental picks, and things like that, and brushes, and we slowly expose the bone. It's kind of hard to see at first, but once we get it cleaned off, you'll be able to see it a lot better. Yeah, everything you're seeing here that's dark colored is bone, and the gray is the rock that's surrounding it.

So what we would do next is we would come here and we'd excavate around this. And we kind of leave this suspended on a pedestal. And then we cover the bone and the surrounding rock and the pedestal with plaster. Generally, we take strips of burlap and plaster, and we'd cover it with a little separator in between, usually toilet paper or tissue paper, to keep the plaster from sticking to the actual bones.

And then, after we have it all pedestaled, and a plaster cap on top, we'd undercut it, flip it over, put plaster on the other side, and then that's basically a handy carrying case to bringing it back to the lab. And then once we had it in the lab, we'd open it up and remove all the rock, glue together all these broken cracks and stuff. And pretty much you'd end up with the whole element, just like you see in the museum.

Credit: Dr. Richard Alley

Want to see more?

Optional Enrichment (no, these won't be on the quiz!):

Agate Chunks in Sand - The formation of fossils is both rare and normal—most dead things are eaten, burned, or otherwise recycled before they are turned to stone, but over the diverse environments of the planet, conditions favoring fossilization are bound to occur in some places at some times. Here, Irene Meglis and Dr. Alley use a little geological sleuthing to understand why the fossil trees of Petrified Forest National Park were preserved. (Transcript)

Deep Time film clips - What do beauty, saving money at Las Vegas, religion, oil exploration, emerging new diseases, and the planet’s recovery from global warming have in common? All in some way involve deep time, the immense age of the Earth. Eric Spielvogel filmed a discussion of these and other issues with Dr. Alley, for a special “time” issue of Research! Penn State. These "Deep Time film clips" will give you something to think about, and may even help with the course. Enjoy!