This eighth-grade science lesson is about rocks. It is the fifth lesson in a sequence of 11 lessons on the same topic. The lesson is 41 minutes in duration. There are 29 students in the class.

00:00:08All right, let me show you something from yesterday.
00:00:22Given enough time, and enough... depth, what's gonna happen to the sediments?
00:00:33What's gonna happen, there Yolanda?
00:00:35It's gonna become cemented.
00:00:38That's good.
00:00:43Now if- how are you gonna spot, how are you gonna identify sedimentary rock when you see it?
00:00:54What's (it have)?
00:00:59You have deposition.
00:01:01Well, you're telling us certainly how it's made.
00:01:06And, you know, that's certainly a good thing, all right? But I- I just want to come back to this.
00:01:15You know, we know how it's made.
00:01:18Sediments get deposited, buried and cemented together, as Yolanda tells us, and it forms sedimentary rock.
00:01:28But my question is, how are you gonna spot it, how are you gonna identify it when you see it?
00:01:36There's a lot of roads that are cut from sedimentary rock, and you can see it if you know what to look for.
00:01:45What's that, Samuel?
00:01:47When it- certain rocks might have layers on it.
00:01:58Let's see.
00:02:02Like that?
00:02:05Now, how do you know that's sedimentary rock?
00:02:06Because it's-
00:02:07How do you know? How do you know? How do you know, Nikita? Look at it.
00:02:14Because it's stuck together.
00:02:16How do you know it's stuck together?
00:02:18Because it's in layers.
00:02:20Say that.
00:02:21Because it's in layers.
00:02:22Okay. That's what- who said that?
00:02:25That's what Samuel said. Absolutely. Absolutely.
00:02:30So, you know, just in a cross-section, looking at it from the side, it appears like that.
00:02:39All right. Now, how do you- why do you suppose you can see the layers here? Because if this river wasn't here, you wouldn't see the layers.
00:02:47What did the river do to the rock? At least the sedimentary rock? What's happening here, Corey?
00:02:53(inaudible) make stratas.
00:02:55That's good. You know, the word- that's a good word. Another word for layers are strata.
00:03:03Okay, but what did the river do to the sedimentary rock?
00:03:10We did this. What is that, Eric?
00:03:13It cuts into it.
00:03:14That's right. So here's a wonderful example of a river- it's the Colorado River- cutting a canyon,
00:03:22and in canyons, if the river is cutting through sedimentary rock, you could see the layer. Now, let me ask you this.
00:03:30Suppose- and this was our little model from yesterday- suppose when the sediments got deposited in- in some ancient sea.
00:03:46Suppose- suppose an animal, the remains of an animal, got deposited in the river along with the sediments.
00:03:57So now we have an animal, you know, that could have been buried... a million years ago, 10 million years ago, 50 million years ago.
00:04:10What do you think's gonna happen to that animal?
00:04:17Rudy, what do you think?
00:04:18It's gonna blend into the rocks, with the rest of the sediments.
00:04:23That's right. Now, there's a word for that. There's a word for that.
00:04:31What's that, Sonia?
00:04:33Becomes fossilized.
00:04:34That's good. Very good.
00:04:43I'd love to pass it around, but since it's sedimentary rock- you can see the layers here- I'm afraid that it's gonna fall down and crack.
00:04:51So I'll just come around. How do you like that, Terrence?
00:04:57Like it.
00:05:12You did good yesterday, Antwone. All right. Now, let me ask you another question.
00:05:19Suppose we dig down further into the sedimentary rock, into a layer that's underneath it.
00:05:28Maybe- maybe this fossil of a fish is found in here, and maybe something like this-
00:05:42is found below it.
00:05:44What is that?
00:05:45Well, it's called a brachiopod. And to us it looks like a clam. It's a shelled animal. If you had this fossil and you found it over here,
00:06:03which would you say is older?
00:06:06The one at the bottom.
00:06:08Which would you say is older?
00:06:13What would you say, Aisha- Angela?
00:06:16I'd say the one (inaudible).
00:06:17This one is older?
00:06:18No, //the other one
00:06:19//No. The bottom one.
00:06:20Why is the bottom older?
00:06:21Because it's more down.
00:06:23That's right.
00:06:26So I- so obviously the- the strata or the layers on the bottom are older than the ones on the top.
00:06:34Now, you could use this.
00:06:35This is how geologists go about figuring out what animal came first and what animal came second and what animal came third.
00:06:45So it's almost like looking back in a book, where the pages at the bottom contain fossils that are older than the pages on the top.
00:06:59All right. Now, let me show you something. Let me shut this. Corey, you want to get the lights for a minute?
00:07:11Don't laugh.
00:07:14Sonia, I told you not to laugh. Oh.
00:07:19I love your pants. Loving it.
00:07:25All right. Any idea where I am?
00:07:29Any idea?
00:07:32Yeah, um-
00:07:37Well, I don't mean the exact- I can tell you the exact location, but the type of landscape I'm on.
00:07:45No. It's not ice, Samuel.
00:07:47It's a-
00:07:51Is it a mountain?
00:07:52It's a kind of mountain.
00:07:54A cliff?
00:07:55I don't know if you can call it a cliff.
00:07:58It's a rock.
00:08:00I'm standing on rock.
00:08:09Sonia, got a clue here?
00:08:14Delia. I'm sorry.
00:08:21Maybe you're standing on a rock, and the sediments in the middle are eroding.
00:08:27No. That's not how this hole got here. All right. Rudy?
00:08:36A river went in the (inaudible), and it dried out.
00:08:40Let me tell you where it was, all right? This is in an island-
00:08:50Does that help? The island of Hawaii.
00:08:53Hawaiian islands-
00:08:54I got it.
00:08:55There's many islands. The biggest one is- is Hawaii. The one that has the- the capital, Oahu- or Honolulu is on the island of Oahu.
00:09:04But there's something about the Hawaiian islands.
00:09:09What is that? What was that? //Jeffrey?
00:09:11//They're all volcanoes.
00:09:12They're volcanoes.
00:09:13That's right.
00:09:14You're on a volcano.
00:09:17So I'm standing on a vol- near the top of a volcano. Now, if I'm standing on the top of a volcano,
00:09:29Why am I not standing on sedimentary rock?
00:09:38Why do I have to be standing on another kind of rock that we're gonna call non-sedimentary at least for the time being? Why? Paola?
00:09:48Because the lava was probably (running or so)-
00:09:50Can't hear.
00:09:51Because it was probably hot, the rock or the lava was running or something.
00:09:56Well, you're getting close.
00:09:57Moist, or-
00:09:59You're getting close. What is it? What do you say, Carl?
00:10:04Because of the (inaudible) going into the hole, it could probably break off.
00:10:12Wait a minute. We just got through saying not 10 minutes ago that if sediments get deposited in some sea and they get buried deep enough-
00:10:26they may be pressed into sedimentary rock.
00:10:31Now, I'm not standing on sediments, and I'm not standing on sedimentary rock. What kind of rock am I standing on?
00:10:42What is that- what do you say there, uh, Kyra- uh-
00:10:51You're standing on non-sedimentary rock.
00:10:52Yeah, but how is it different than sedimentary rock? Think the way this rock- this rock forms.
00:11:03How did it form?
00:11:04Because, um-
00:11:05How did it form, Terrence? How does it form, Samuel?
00:11:09By heat.
00:11:15Heat is necessary. Sonia?
00:11:18Is it metamorphic rock?
00:11:23What comes out of a volcano?
00:11:27Okay. //Now,
00:11:28//(inaudible) magma.
00:11:29we can call it lava if it comes to the surface.
00:11:33Some lava never comes to the surface. We can't call it lava; we have to call it magma.
00:11:40Once you say magma, you include the magma that comes to the surface that we call lava,
00:11:46or magma that never makes it to the surface, stays underground. Now, look at your charts.
00:11:55What has to happen to magma, or in other words, molten rock- that's where the heat comes in- in order for it to become solid? Think about it.
00:12:07It has to cool.
00:12:08That's right. So if magma cools, it becomes solid, much the same way that when water cools it becomes ice.
00:12:20And what kind of rock is this non-sedimentary rock? It doesn't come from sediments. What is it, Terrence?
00:12:29It's igneous rock.
00:12:31Very good. So there's another type of rock. Now, look at this. Let me lower the screen a minute.
00:12:44So I- I went down the slope of the volcano, I walked about four or five miles, and I came to this sign.
00:13:07So I'm giving away my age. What does it say there?
00:13:15September 1974-
00:13:16Sheba, what does it say? I know if you can see it, the rest of us can see it.
00:13:19"September 1974 Lava Flow."
00:13:22Okay. What kind of rock do you think this is?
00:13:29What kind of rock, Antwone?
00:13:33Magma. Lava.
00:13:34You're right. Lava is magma, but this long since cooled down. This isn't hot anymore. It became solidified. What kind of rock?
00:13:47Okay. So let's put that one on the board. If you had to- if you had to describe how igneous rock is formed, how could you say it in one sentence?
00:14:08One sentence.
00:14:15One sentence.
00:14:17Cold lava.
00:14:18What would you say, Terrence? One sentence.
00:14:29I don't know.
00:14:32It's on the chart right in front of you.
00:14:47You see it?
00:14:49All right. How does igneous rock form?
00:14:57How does it form, Kyra?
00:15:00Igneous rock is formed when magma cools.
00:15:02Can't hear.
00:15:03Igneous rock is formed when magma cools, (magma).
00:15:14Now, when magma cools, what happens to the state of matter that it's in? There's a change in state of matter?
00:15:22Yeah. So what's the change, Rudy?
00:15:24From liquid to solid.
00:15:25Okay. So it becomes solid so we could say it solidifies.
00:15:34There you go. All right. Now, look at this.
00:15:41What evidence is there that this is igneous rock? Look at- look at the surface. Look at the surface.
00:15:57Look at the surface.
00:16:05Touch it.
00:16:06How come you don't want to touch it?
00:16:07It's not hot anymore.
00:16:13All right. Anyone see any evidence? Remember, it was once liquid.
00:16:21Oh, oh, oh, I know.
00:16:22What do you see there? What do you see, Terrence?
00:16:26It's like- the little holes inside of it.
00:16:29Well, you're right. What do you think the little holes are from?
00:16:32Bubbles. Bubbles.
00:16:34What kind of bubbles?
00:16:35Magma bubbles or lava bubbles.
00:16:38Well, what makes bubbles?
00:16:44Air. Some kind of gas.
00:16:46So when this magma came up through the volcano in Hawaii, the magma that it contained had a lot of gas in it.
00:16:58I guess it was something like club soda, has bubbles in it. So when the rock cooled and solidified-
00:17:04The holes-
00:17:05The holes- yeah. The holes became preserved. All right? Now, take a look at your chart. I want to show you something.
00:17:14Right under the rock cycle chart is a scheme for igneous rock identification.
00:17:25Now, you see where it says vesicular?
00:17:29You see? Look where I'm pointing.
00:17:31Vesicular means gas bubbles. So what I'm holding is vesicular basalt, all right? Gas bubbles. You could write it right on your chart.
00:17:45All right? Now, I want to show you something else.
00:17:50All right. I'm gonna pass back two igneous rocks. In a way they're almost the same, and in another way they're different.
00:18:01It's hot.
00:18:02Well, that's because it was near the projector. All right. I just want you to look at it and then pass it back.
00:18:08You can touch it, but pass it back, because one of these is a fairly rare rock, and I don't have enough for everybody.
00:18:17Pass it.
00:18:19(inaudible) pass it.
00:18:20Okay. I'm gonna give one to Antwone.
00:18:27All right. Now, take a look at this.
00:18:31Now, I'll tell you up front that you're looking at igneous rock, two different samples. Now, if I- if it's igneous rock, where did it come from?
00:18:49All right. Well, yeah. Don't call it mag- don't call it lava. Let's call it magma.
00:18:58Now, let me tell you a little story.
00:19:07Here's a cross-section of some part of the crust of the earth. Now, what do you think these horizontal layers are?
00:19:21What kind of rock?
00:19:25What kind of rock?
00:19:27What kind of rock comes in layers?
00:19:30Yeah. All right? So these are different types of sedimentary rock, the layers. Oldest is on the bottom.
00:19:37Now, what does it say- what does it say here, Kyra? If you can see it, everybody can.
00:19:44Magma source.
00:19:45Magma source.
00:19:46Okay. So at one time this was molten. What happened to at least some of the magma? Look.
00:19:56It went up.
00:19:57Well, what happened? What happened, Corey?
00:19:59It went up.
00:20:00That's right. And what we say is it intruded into the rock that was already there, so we call this an igneous intrusion.
00:20:12Sort of intruded into the rock that was already there. Now, let's follow this intrusion. Where did this intrusion wind up?
00:20:23On the surface.
00:20:24Ah. Okay. Now, that could be a kind of volcano that they have in Hawaii- they're called shield volcanoes-
00:20:32because the magma is very liquidy and loose, so it spreads out.
00:20:37Now, why would this magma that came out at the surface cool faster than the magma, let's say, that never made it to the surface?
00:20:51I mean, there's a lot. I'm just using this as an example. Cools slowly. Why? Why is that, Delia?
00:20:59Because maybe the air made it cool faster, that's on the surface.
00:21:02That's exactly right. As a matter of fact, some magma cools even quicker. There's magma- there are volcanoes under water,
00:21:10and the magma comes up and freezes much quicker than it does in the air. But, anyway, how many people have ever made rock candy?
00:21:22All right. The longer you let that string hang in the water, what about the size of the crystal? Did you make it that way?
00:21:33No, never-
00:21:34All right. Let me show you something. Magma is a liquid, and in the liquid you have charged atoms.
00:21:44In the seventh grade, you learned that atoms when they become charged, when they become dissolved,
00:21:53when they became liquid form- when the state of matter changes, they become ions.
00:21:58Now, since this is magma and it's a liquid, the atoms can move around. What do you think's gonna be attracted by a positively charged ion?
00:22:18Right. So given enough time, positive atoms- positive ions attract negative ions and negatively charged atoms, and they'll-
00:22:31they'll line up due to electrical charges. Given enough time, they arrange themselves very orderly, and you might wind up with something like this.
00:22:49That's cute.
00:22:51What is it?
00:22:52A crystal.
00:22:53It's a crystal.
00:22:54It's a cry- That's all a crystal is. It's an orderly arrangement of atoms,
00:22:56and the atoms align- aligned themselves when the magma was liquid, when it was in a liquid state.
00:23:04So the longer the magma stays liquid, what can you say about the size of the crystal?
00:23:10It gets bigger.
00:23:11It gets bigger. Okay. But suppose the magma comes out at the surface and cools real quick.
00:23:20What's gonna happen to the charged atoms? Will they have a chance to line up and become-
00:23:28All right. Now, remember the rocks I passed back.
00:23:34There was one that had big crystals, and there was one that had small crystals. Who has the rock now?
00:23:43All right. Do me a favor, Shevaun. Hold up the one that you see has big crystals.
00:23:53Okay. And how do you know it has big crystals?
00:23:56Because it's kind of sparkly (inaudible).
00:24:00Yeah. Here it is. Well, here it is. I put this down on my floor.
00:24:06No, it's not- you can see //the-
00:24:09That's right. It's granite.
00:24:12All right? So this- this, that cooled under ground, the crystals had time to line up, the magma took a long time,
00:24:21because it cooled very slowly, so you get large crystals.
00:24:31But where the magma- but where the magma comes out at the surface,
00:24:37atoms don't- and magma freezes really quickly, atoms don't have time to line up, you get small crystals.
00:24:47Okay? Now who else has the rock now?
00:24:50Okay, Antigua, hold up the rock that cooled quickly.
00:24:57Hold it up. How do you know that cooled quickly?
00:25:00Because it doesn't have a lot of crystals.
00:25:03Can you see the crystals?
00:25:05Can you see little specks in there?
00:25:10Those may be those tiny crystals, all right? Now, one more thing. If you're wondering how I'm naming these rocks, it's all on the chart.
00:25:22First of all, is the rock that you are holding- is it light colored or dark colored?
00:25:31Light colored.
00:25:32Light colored. Okay. Now, notice on your chart it says color: light. So these rocks over here are all light in color.
00:25:45Now, according to the chart, what the- what's the color of these igneous rocks?
00:25:52Yeah. It says "dark." So since they're light in color, I know and you should know that it could be granite or rhyolites,
00:26:04or even a rock called the pegmatite. Now, look over here where it says grain size.
00:26:14That's a way of describing the crystal size. You might want to write "crystals" here.
00:26:23All right? Which of these- which of these word- which of these correspond to something that has a fine grain or tiny crystals? Look at the measurements.
00:26:34Less than-
00:26:35Okay. Less than one millimeter or less than a tenth of a centimeter, light colored. That rock is rhyolites.
00:26:47But if it has bigger crystals, let's say a tenth or one millimeter to a centimeter big-
00:26:55It's granite.
00:26:56That's right. Then it's granite. So it's really very simple.
00:27:03Now, if the rock took a real long time to cool, if it's one centimeter or 10 millimeters or larger, then it's called pegmatites.
00:27:19Let me see. Here's the pegmatite. Look how big those crystals are. There's one crystal right here. It's feldspar. All right?
00:27:34So this one took a real long time to cool. The crystals are really big. We say it has a very big grain size. Okay. Let's wrap this up.
00:27:49How do you know by looking at an igneous rock, where the rock cooled?
00:27:54Where the magma cooled? What's the general rule, Yolanda?
00:28:00Maybe because it has a different type of rock in it.
00:28:04Look at the rock. How do you know that the magma that formed an igneous rock cooled underground? How do you know, Rudy?
00:28:13Probably because of the size of the crystals.
00:28:14Okay. So as the magma cools underground- Rudy, what did you say?
00:28:21The size of the crystal.
00:28:23Well, tell us about the size.
00:28:25//The size- the size of the-
00:28:26//Big? Little?
00:28:32And on the other hand, if the magma came out at the surface maybe through a volcano-
00:28:47Then what's gonna be the size of the crystal? What, Terrence?
00:29:01All right. Now, listen to this question. Here's another igneous rock.
00:29:16You see any crystals in here, Eric?
00:29:19Okay. Tiny crystals. What's the name of this rock? Look at your chart. Look at your chart.
00:29:29Here. I got one that was transported by a stream. What's- very ti- well, it's round.
00:29:37Oh, my gosh.
00:29:38It's really heavy.
00:29:42What's the name of it, Shevaun?
00:29:45Very good. How did you get basalt?
00:29:48Since Eric said it was tiny in crystal.
00:29:52I looked at "less than one millimeter."
00:29:54Very good.
00:29:55And I looked at the dark side.
00:29:56Ah. (inaudible) dark. Basalt: small, tiny crystals, dark in color, and- look- here are the minerals that make up the rock.
00:30:12Here are the minerals that make up granite and rhyolite.
00:30:17Why do you think granite and rhyolite are light in color? What does that tell you about the minerals- the color of the minerals that make it up?
00:30:25It has to be-
00:30:27It has to be a light color.
00:30:28Yeah. And look: quartz, clear to white; feldspar, pink to white.
00:30:36So the rock is white- light colored, because the minerals that make up the rock are light.
00:30:43But on the other hand, different parts of the world have different magmas. It's like soup.
00:30:51So this soup, or this magma, contained dark ones. Here's a dark green. All right? Here's a little bit of black.
00:31:01So now you know how to name the igneous rocks. Now, suppose you had an igneous rock that cooled so quickly no crystals had time to form.
00:31:11What's the name of that rock? I can't pass this around because it happens to be very, very sharp.
00:31:20Ballistic glass.
00:31:22That's right. It's glass.
00:31:29If you ever wondered how did the cavemen shave- how do you- how do you- how did they shave before they had-
00:31:36With rocks.
00:31:37With basaltic-
00:31:38With rocks.
00:31:39This. If you hit it the right way, it flakes off, and you get something as sharp as a razor blade, even sharper than a razor blade,
00:31:49and that's how they shaved.
00:31:53No, really, //if
00:31:54//Was it like that?
00:31:56//I mean- that's how they shaved, and another thing is, this is- this is one of the items that Indians used as arrowheads and knives.
00:32:04All right? Now, here. How did you know that, Shevaun?
00:32:10Where does it say that?
00:32:12Right here-
00:32:13It's at the top.
00:32:15It's ballistic glass.
00:32:17No crystals. No crystals tells you something about how fast the magma cooled.
00:32:24It cooled real fast.
00:32:25Right. So in this case there's magma that cooled so quickly no ions have time to line up,
00:32:34and you get obsidian if it contains these minerals or basaltic glass if it contains the darker ones.
00:32:46All right? Now, I sometimes do this. How did- how did the cavemen-
00:32:51or how did the American Indians, people that- or before they invented- discovered metal, how did they flake these?
00:33:00How do you make a tool out of this?
00:33:02Scrape it against another rock.
00:33:03No. They didn't do that.
00:33:07They didn't do that. And they made some very fine tools out of this.
00:33:15I think the Egyptians used this as scalpels. They did operations. So did the Indians in South America. They did operations.
00:33:23They didn't have knives- well, they had knives, but how do you fashion this into a sharp-edged tool? How, Sonia?
00:33:31They could take it and they (chopped) it on the ground or something.
00:33:40Take a (inaudible) the same thing.
00:33:41All right.
00:33:42I see, you have to take a-
00:33:43I'm not gonna do it; I'm afraid it's gonna fly off and hit somebody, but if you hit it just the right way-
00:33:48they used their hands and another tool to bang it on. If you hit it just the right way, you get these flakes that are real sharp.
00:34:09I think one went into my finger. I feel a little splinter.
00:34:12It's right there.
00:34:18Clean as a whistle. It's as sharp as any razor blade.
00:34:30All right? How many people saw the movie Congo?
00:34:36Okay. I didn't see it. My son told me about it. It has to do with diamonds, right?
00:34:43All right. Delia, what about the diamonds? Where were they?
00:34:47They were in some cave.
00:34:49How big were the diamonds?
00:34:53I don't remember.
00:34:54All right. I read an article just two days ago. They didn't use real diamonds.
00:35:01(It was fake?)
00:35:02They didn't use glass.
00:35:05They used a mineral that you find in granite. It's the clear one. It's called quartz.
00:35:13All right? Now, this crystal of quartz, is kind of rare because it's called the twin. It has a point on both sides.
00:35:31Not like this one that has- it's only pointed on one side. Now, as far as I know, there's only one place that has these quartz.
00:35:41It's called Her- it's found in the city of Herkimer, New York, and they call it a Herkimer diamond.
00:35:49It's not really a diamond, but it has this shape like a diamond, and that's what they used as diamonds in the movie Congo.
00:35:59All right? Now, I told you- we talked about Cooperstown- Cooperstown, New York.
00:36:08Remember Cooperstown? Remember Howe Caverns?
00:36:14Right, Howe Caverns?
00:36:15Well, if you go into Howe Caverns to see the limestone cave-
00:36:27All right? Right here. I think it's a little north of Albany.
00:36:34If you go a little further north- remember the Baseball Hall of Fame is here- you have the town of Herkimer
00:36:43and as soon as you get into the town of Herkimer you see signs, "Visit the Herkimer Diamond Mines," and that's where it is.
00:36:50You go to the Herkimer Diamond Mines. They rent you- Antwone, you looking for it?
00:36:57You see it? You can rent hammers, goggles, and they'll send you out into this cliff, and you can hack away at the rock,
00:37:10and that's how I found the- this Herkimer diamond. They're there for you- they're there for you to get.
00:37:18Yeah. So it's- it's kind of a neat geology- neat geology trip to go to Howe Caverns, go a little further north, and find- mine Herkimer diamonds.
00:37:32They're very- I don't think they're found anywhere around the earth except in Herkimer, New York.
00:37:40All right, now let me ask you- here's a tough question.
00:37:57Okay. How many people saw ET? Does that look familiar?
00:38:04That look //familiar?
00:38:07This is in Yosemite National Park. It's called Devil's Tower. I believe it's in Yosemite. It's out west. Now, this is solid granite.
00:38:20How could you explain- since granite cools underground slowly- that's why it has big crystals-
00:38:27how in the world can this piece of granite be above the surface?
00:38:42What do you think, Paola?
00:38:47Oh, um-
00:38:49All right. This has large crystals. It cooled slowly, it cooled underground, but yet here it is.
00:39:03What do you say, Eric?
00:39:05I don't know.
00:39:06What do you say, Carl?
00:39:09What do you say, Corey?
00:39:13I don't know.
00:39:15There is probably more (than one layer of it).
00:39:16No. Samuel?
00:39:18Maybe- since it's underground, maybe it was pushing up on the surface, and the surface just probably cracked, and it just came up.
00:39:26Oh. You mean- what are you saying? It really did cool underground?
00:39:31All right. So if it cooled underground, that would account for the large crystals.
00:39:41But you see it now above ground- so what do you say, Yolanda?
00:39:47Maybe it cracked the ground, and it came- and it just kept rising.
00:39:52So you mean something pushed it up?
00:39:56Okay. That's very good.
00:40:04It was pushed up, but at one time it was an intrusion, and there was rock around it.
00:40:17And it broke off.
00:40:19What happened to the rock around it?
00:40:22Or what could have happened to the rock around it? And think back to Niagara Falls.
00:40:31Because (inaudible).
00:40:34Water went over it, and it pushed up.
00:40:37It might have been water, what?
00:40:39The thing that rubbed against it.
00:40:41What wore away?
00:40:42The rock.
00:40:43The rock.
00:40:44The s- why?
00:40:45Because they were soft.
00:40:46Very good. It must have been softer. Okay.
00:40:50That was a good lesson.
00:40:51Thank you. Yeah. All right.