THE ROCK CYCLE
The rock cycle is a process that is constantly going on on Earth. It is something that has been happening since the creation of the planet and is something that will continue to happen forever. Without the rock cycle, there might be little to no diversity among the pebbles and stones all across the world.
In short, the rock cycle is a process that involves magma, heat, pressure, erosion, and, of course, the three types of rocks on Earth. The three types are igneous, sedimentary, and metamorphic. All are formed differently and all are formed through the rock cycle.
To start the process off, there is magma under the crust of the Earth which is there until a volcano spews it out. The alternative for it is to squeeze into the crust far enough to cool, but not onto the surface. The agent of change here would be the cooling down of the magma. When it does cool down and solidify, the magma is igneous rock. The word igneous comes from the Latin ‘ignis’, which means fire. If it is formed under the crust, then the grain of the rock tends to be coarse (large enough to be seen without a magnifying glass) because it cooled slowly. If it cools quickly on the surface, then the grain is very fine, or not able to be seen altogether. An example of rock formed intrusively (under the surface) would be granite, and one formed extrusively (on the surface) would be pumice.
Then, the rock can do a few different things. It could melt down again to become a new igneous rock, but to do so it would have to go deep underground. Another course could be to stay deep underground, but not deep enough to melt, and become a metamorphic rock. Agents of change for this would include heat and pressure, and a lot of both. The last course of action would be to get eroded down to small pieces called sediment. Eventually, enough sediment could pack together to make a sedimentary rock, but the special condition for that to happen is the rock would have to be on the surface to erode in the first place. Years of wind, rain, sun, snow, hail, and various other forms of abuse and weathering would beat the rock down until only the sediments remained to be washed away and packed into sedimentary rock.
Sedimentary rock can also be made from other substances, too, such as shells, bones, and other debris that settles with the small pieces of rock. Usually, all of this settling is done in a lake or some other body of water. All of the sediment is compacted together with layers on top of layers adding pressure over many years, until it is cemented into rock. This sedimentary rock also has paths it can take. It can wear down again and make another sedimentary rock, or it can somehow melt into magma and make new igneous rock. Or, it can be buried even more from its sedimentary rock state and eventually build up enough pressure and heat to metamorphose into a metamorphic rock.
The metamorphism of any rock to a metamorphic rock is a process that almost completely changes that rock. Minerals can be added or removed, and grain sizes can change; usually they enlarge. Once a metamorphic rock, the rock can also follow a few courses, like always. It can go to the surface and erode into a sedimentary rock, or it can undergo more metamorphism into a new metamorphic rock. Or, it can melt into magma and complete the rock cycle.
All in all, rocks are constantly changing, whether they’re melting, eroding, or metamorphosing into some other type of rock. There isn’t really a beginning to the cycle, or much of an end. The same material has always been on Earth, it’s just in a state of continuous alteration; to mix things up a bit. Earth is pretty quick about it too, because we have water to erode and cool rocks where other planets do not. Also, our atmosphere is thick and diverse, able to put gas bubbles into rock, and we have winds to erode and move rocks as well. Other planets don’t have those advantages that we do, so they cannot change as quickly as us. Because of that, I hypothesize that our planet has more sedimentary rocks than others do.