• 2 months ago
Transcript
00:00Can you guess what this video is about? Yeah, we kind of gave it away, didn't we?
00:05That's right, we are learning about rocks in this video. Rocks are all around us.
00:12You see rocks all the time and some rocks are huge, like the rocks that make
00:17up this massive rock formation. They're huge, but then sometimes rocks can be
00:23really tiny, wee-wee tiny little baby rocks. Rocks are amazing and they're all
00:29around us. Alright, so what are rocks? Well, rocks are solid chunks of one or
00:38more minerals. Rocks are mineral chunks! There are solid chunks of one or more
00:45minerals. Now, most rocks are mixtures of multiple minerals, like these rocks. Other
00:56rocks are made up of just one mineral, like in this picture. This is a picture
01:02of chalk. Chalk is a type of rock made of a mineral called calcite. The next time
01:11you play with chalk, just think, wow, this is made of calcite! These are like sticks
01:16of calcite! Chalk is a rock that's made of calcite. So, rocks are solid chunks of
01:26one or more minerals and they are super fun to learn about. That's why
01:31geologists are so cool. Geologists are rock experts. They study rocks as their
01:38job. Geologists disagree about how many different types of rocks there are, but
01:46we can all agree on this. There are so many different types of rocks. To make
01:50things more simple, rocks are put into three categories, three major types of
01:56rock. Sedimentary, igneous, and metamorphic. Can you say those with us?
02:04Sedimentary, igneous, uh-huh, and metamorphic. Yeah. Now, this is pretty
02:13interesting. The category that a rock belongs to tells us how that rock was
02:19made. Here, we'll show you with our first category of rocks, sedimentary rocks.
02:28Alright, so what are sedimentary rocks? Sedimentary rocks are rocks that are
02:34made up of little particles. They're made up of little particles! The particles are
02:41called sediment. Can you say that with us? Sediment. Yeah, sediment. An example of
02:48sediment is sand. Yeah, sand is a type of sediment. It's kind of cool. Seashells
02:56are an example of sediment as well. So, there are lots of different types of
03:01sediment, but they're particles. They could come from non-living things, like
03:05sand, or they could come from living things, like seashells. That's fun.
03:10Sedimentary rocks are made up of little particles called sediments, and you can
03:16even tell that from the name, sedimentary. Sediment is in the name! So, if you forget,
03:24just look at the name. Sedimentary. Sediment is in the name! So, the way
03:31sedimentary rocks are formed is by sediments collecting at the bottom of
03:36bodies of water, like lakes and oceans. The sediment is pushed down by the water,
03:42and over time, the sediment starts to harden into rock. Water is what really
03:49makes sedimentary rocks. Without the water, the sediments would never harden
03:54to become sedimentary rocks. They need water! Just think, in that water right now,
04:02sediments are getting pressed down and are hardening to become rock. The
04:07molecules in the water help the sediment stick together, kind of like
04:12cement. That is how sedimentary rocks are made. Okay, we have two categories left.
04:22Let's learn about metamorphic rocks next. Metamorphic rocks are made when a rock
04:29goes through a lot of heat or pressure.
04:33Remember, sedimentary rocks need water to be formed. They need water. Metamorphic
04:41rocks are different. Metamorphic rocks are rocks that need heat or pressure to
04:47be formed. Here's a simple way to remember that. The word metamorphic has
04:53another word inside of it, the word morph. That's interesting. The word morph
04:59means to be changed. So, when you think of rocks that are changed by heat or
05:06pressure, think metamorphic. Metamorphic rocks morph. They are changed by heat
05:14or pressure. Metamorphic rocks are formed below the Earth's surface. That's cool.
05:23And here's the thing. They make up a lot of the Earth's crust, which is the outer
05:29shell of the Earth. Much of the Earth's crust is made of metamorphic rocks. So,
05:36we're not talking about this type of crust. We're talking about the Earth's
05:40crust, okay? You can see that the Earth's crust, the outer shell of the Earth, is
05:47broken up into these things that almost look like puzzle pieces. Scientists call
05:53these plates. Here is a map of these plates, okay? And they have a really cool
06:00name. Scientists call them tectonic plates. Can you say that with us? That's
06:04so cool. Tectonic plates. These huge plates move and push against each other.
06:11And there is a lot of heat and pressure there. Oh. That's why there are so many
06:19metamorphic rocks that form in and around the Earth's crust. Wow. Mystery
06:25solved. And this is cool. The heat and pressure not only change what the rock
06:30looks like on the outside, they change what the minerals themselves are like. So,
06:35the rock actually changes form. That means the heat or pressure morph the old
06:42rock into a new rock. A metamorphic rock. Now, sometimes sedimentary rocks get
06:51pushed into the Earth and are around pressure or heat. Then the sedimentary
06:57rock turns into a metamorphic rock. It morphs or changes into a different rock.
07:04It has become metamorphic. So, heat or pressure create metamorphic rocks. And
07:11they usually form deep under the surface of the Earth in and around the Earth's
07:17crust. All right. Now, we've come to our final rock category, igneous. This is
07:26really interesting. Igneous rocks are formed when molten rock cools and hardens.
07:34You might be wondering, what does molten rock mean? What is molten rock? Well,
07:40this is molten rock. Molten rock is liquid rock. And there's two forms of it. Inside of the Earth,
07:48molten rock is called magma. That's right. Magma. But when it comes out from inside the Earth,
07:57it is called lava. Lava is molten rock too. Lava is molten rock that is no longer inside of the
08:06Earth. So, igneous rocks are formed when molten rock cools, and that molten rock can be magma or
08:15lava. Do you remember how metamorphic rocks are formed from pressure or heat? Well, igneous rocks
08:23are kind of the opposite, aren't they? Igneous rocks are formed from molten rock cooling. Isn't
08:29that interesting? Metamorphic rocks are formed from pressure or heat,
08:34and the igneous rocks are formed during this cooling of molten rock.
08:43Sometimes, metamorphic rocks are heated so much they turn into molten rock. When this molten
08:50rock cools, it becomes an igneous rock. That's pretty cool. A common place for igneous rocks
08:58to form is a volcano. The lava that erupts out of a volcano cools, but the magma below a volcano
09:05can cool as well, forming igneous rocks. Remember, rocks are chunks of minerals. They are mineral
09:15chunks, and they are grouped into three different categories. The first category was sedimentary.
09:23Sedimentary rocks are formed when particles called sediments join together. It is almost
09:29like they want to be friends as they form a new rock. The second category was metamorphic.
09:37Metamorphic rocks are formed from heat or pressure. It is almost like when someone
09:41gets angry, their face, actions, or words can be changed or morphed. Finally, the third category
09:50was igneous. Igneous rocks are formed when molten rock cools off. This molten rock can be either
09:57magma or lava. Igneous rocks are like when someone was really angry but decides to take deep breaths
10:05to start to cool off. Igneous rocks are formed when molten rock chills out. We've talked a little
10:13bit about this as we've learned about these types of rocks, but rocks change. Scientists call it the
10:19rock cycle. Igneous rocks can break apart into sediment and become sedimentary rocks. Sedimentary
10:26rocks can be pushed into the earth and become metamorphic rock. Metamorphic rocks can turn
10:32into liquid rock and cool into igneous rock. That's amazing, isn't it? That is called the rock cycle.
10:42It's fun to learn about rocks. Next time you find a rock, find out what type it is and think about
10:47all that that rock has gone through. Rocks aren't just chunks of minerals.
10:52They tell a wonderful story about how the earth works.