Middle school Earth and space science - NGSS
The rock cycle
The rock cycle describes how the three main rock types—igneous, sedimentary, and metamorphic—change from one type to another. These changes occur through processes such as melting, solidification, and lithification. The rock cycle is driven by energy from Earth's interior and the sun. Created by Khan Academy.
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- How long does it take for a rock to be in a different form?(19 votes)
- The short answer is that the rock cycle takes millions of years. Keep reading for more detail.
Creating metamorphic rocks takes millions of years because the rocks have to be buried deeply to be exposed to high temperatures and pressures to be metamorphosed.
In most circumstances, creating igneous rocks also takes millions of years. The process of subducting rock, it melting, and then either erupting or recrystallizing underground is a very slow process.
Creating sedimentary rocks takes thousands or millions of years. To create sedimentary rock you have to go through the processes of erosion, deposition, burial, compaction, and cementation. With siliciclastic sediments this is a million year process. But it can be done in less time with carbonates.(26 votes)
- Do Rocks take affect by season??(5 votes)
- No, you must remember, we are talking about thousands of miles beneath the Earth's crust. The seasons have no effect on the magma beneath the Earth.(6 votes)
- Why do most of our math words come from greek or Latin names? For example, at0:50"this term comes from the Latin word igneus," why?(4 votes)
- In Europe, many people who studied these things used Latin to communicate with each other. Even if two scholars usually spoke different languages, Latin was a kind of common ground for them. Many scientists followed from this tradition and talked about things using Latin-derived words.(6 votes)
- what do you mean by the lava and magma lamp?(5 votes)
- A lava lamp is a somewhat popular decoration. It’s basically a tube full of wax and/or other materials with a heat source at the bottom.
The video was just suggesting a way to remember the difference between lava and magma. Lava is liquid rock above the ground, and magma is liquid rock below the ground. It doesn’t really matter how you remember that.(4 votes)
- Can all types of soil,dirt, and sand turn into rock?(2 votes)
- Yes. Soil, sand, and dirt can all lithify into rock. Soils that have turned into rock are called paleosols and aren't very common but I've seen them.(8 votes)
- why is rock sole or hard ?(5 votes)
- The chemical bonds that hold atoms together in these minerals are stronger in some than in others, and the atoms themselves determine which bonds are stronger than others. Stronger bonds make for stronger minerals and, thus, harder rocks.(2 votes)
- Which rock takes the longest time to shapeshift?(5 votes)
- Sedimentary rocks take the longest time to form as these rocks undergoes lots of processes such as erosion, weathering, dissolution, precipitation, and lithification before it could be formed.(1 vote)
⠀⠀⠀⠉⠛⠛⠿⠿⠶⠶⠶⠶⠶⠿⠿⠿⠟⠛⠛⠋⠉⠀⠀⠀⠀⠀⠉⠉⠛⠛⠻⠿⠿⠿⠶⠶⠶⠶⠶⠾⠿⠛⠛⠋⠁please upvote(4 votes)
- I love rocks! I even have a whole collection of them and some crystal rocks(4 votes)
- [Instructor] Have you ever tried to hold a staring contest with a rock? If you did, you might not have expected that all that time you were staring at one of the sneakiest shape-shifters in the world. No, rocks don't shapeshift into unicorns, but they do change shape and composition. Sometimes they change quickly, like when an interrupting volcano launches molten rock into the air. And sometimes they change slowly, like when a rock is heated and compressed in the earth for thousands to millions of years. When geologists stare at a rock, they can figure out the rocks composition and tell the story of how it was created. And it turns out rocks can be made in many different ways. When put it the right combination of heat and pressure, rocks can become molten and liquid. When this molten rock cools and becomes solid, we call the rock it makes igneous rock. This term comes from the Latin word igneus, which means fiery or burning hot. Igneous rocks make up more than 90% of the Earth's crust. One common kind of igneous rock is granite, which you've probably seen in bridges, buildings, and countertops. Another kind of igneous rock is obsidian, which is smooth and glassy, and is sometimes used to make knife weights. Both of these rocks were made of molten rock. So why do they look so different? Well, granite was made from magma, which is molten rock that exists below the surface of the earth. Magma tends to cool slowly underground, which gives time for the elements in it to form large crystals. And this obsidian rock was made from lava, which is molten rock that flows above the ground. Lava tends to cool quickly, which causes the rocks it forms like obsidian, tuff smaller crystals. I always remember the difference between magma and lava like this. I keep my lava lamp above the ground, just like lava is above the ground. If I buried my lava lamp in the ground, then I can call it a magma lamp. Once an igneous rock is created, its journey isn't over. The rock might begin to change through a process called weathering. This is when water, weather, wind, and other physical forces chip away at a rock and cause little pieces to break off. These little particles are called sediments. The sediment from our igneous rock can be moved around by wind and water. This is called erosion. Eventually, the sediment will settle down somewhere. Maybe at the bottom of an ocean or a lake, and it might join other sediment from other rocks, crushed up shells, and plant matter. And over time, this sediment will become a rock. Rocks that are formed from sediments are called, you guessed it, sedimentary rocks. But how does sedimentary goop at the bottom of the lake become a rock? Well, it goes through a process called lithification. Lith comes from the Greek word for stone. So you can think of this process as stonification. The first step of lithification is called deposition. This is when sediment is deposited in a new location and it spreads out to form a layer. As more and more layers are created, the layers underneath them become squished together. This is called compaction. When water moves to the layers of sediment, it can carry dissolve minerals with it. The water can leave these minerals in between the sediment particles, which makes everything stick together. This cementing of sediment is called cementation. Limestone is a sedimentary rock that is made with sediment that contains a lot of calcium carbonate in it goes through lithification. But once the sedimentary rock has been created, it doesn't mean that it is done changing. Sometimes a rock is squeezed or heated so much that the minerals inside it actually change composition. It is now a metamorphic rock. You might've heard of the word metamorphosis, which describes when something changes from one form and structure to another. Like when a caterpillar turns into a butterfly. Metamorphic rocks are made when igneous, sedimentary, or even other metamorphic rocks change form and structure because of heat and pressure. For example, when the sedimentary rock, limestone, gets put under a lot of heat and pressure, it can turn into marble, but metamorphic rocks still may not be done changing. Rocks can actually keep on changing forever. Igneous and metamorphic rocks can become sedimentary rocks if they're broken apart into sediments and go through lithification. And metamorphic rocks and sedimentary rocks can become igneous rocks when they are melted and then cools. And igneous rocks and sedimentary rocks can become metamorphic rocks when they're exposed to high heat and pressure. This is called the rock cycle. So maybe next time you get the chance to stare at a rock. See if you can figure out whether it's igneous, metamorphic, or sedimentary. And when rocks changed so much, who knows what kind of rock it'll be next.