The 3 Groups of Rock

I'm going to go over the 3 main groups and all the ways that they can become that rock. The majority of this post is really about sedimentary rocks.

Sedimentary:
There are 2 main ways that a sedimentary rock can become a sedimentary rock, but they both are because of sediments.

1. The first way is when other rocks are weathered down into sediment and the sediments are compacted together.
2. The second way is when living organisms die and their sediments are compacted together.

Now, there are many ways that sediments can be formed and carried to the place where they will be compacted together (usually the ocean but not always).
Ways Sediment is formed (mainly erosion):

1. Wind erodes a rock (like in the deserts, almost all of the sand is past eroded rock)
2. A river slowly erodes the rock around it
3. The ocean erodes the rocks inside it as well as the rocks on the coastline
4. Snow on the mountains erodes the rock as it thaws and freezes but also as it slides off
5. Glaciers (especially the ones that move) erode the rocks beneath them
6. Living organisms die and the sediments go to the bottom of the ocean

Ways they are carried to the place:

1. In rivers and oceans
2. The wind carries it (sand storms)
3. Snow and rain that got ash from volcanoes
4. Snow and rain coming off of mountains, hills, roads, forests, etc.
5. Glaciers - they carry sediments from many different places and deposit them along the way
6. Volcanoes shoot ash into the air

Metamorphic:
A metamorphic rock is created when either an igneous, a sedimentary or another metamorphic rock is subjected to extreme heat and/or pressure until the crystals reform.

Igneous:
An igneous rock is when lava/magma cools to form a rock.
The two ways lave/magma can cool are:

1. Slowly: when the lave cools close to the Earth's interior where it is still quite hot, so it cools really slowly, forming extremely large crystals. This is called an intrusive rock because it cooled inside the Earth.
2. Quickly: when the lava cools on the exterior of the Earth where it is very cool (relative to inside the Earth), it cools really quickly, forming very small/invisible to the naked eye crystals. This is called an extrusive rock.

There are two ways that lava can cool:

1. In water: when lava cools in water, it usually cools extremely quickly (as soon as it touches the water) and it forms very light, almost fluffy rocks that are extremely porous.
2. On land: when lava cools on land, it cools quickly but not as quickly as in water, so it is still very light compared to metamorphic and sedimentary rocks because, unlike them, it is still porous, but it's not as light and porous as lava that cools under water.

Hope this helps! :)