rocks
Rocks, what are rocks? Where/how are they formed? Can they change into other rocks? What are the made of? What types of rocks are there? How many different types of rocks are there in the world? All of these questions we need to find out the answers! Want to know all about rocks well you can find out here! There are plenty of different types of rocks. There are sedimentary rocks, metamorphic rocks, and igneous rocks. But, there are plenty different rocks in one family of lets say igneous rocks.
igneous rocks
When hot lava or magma cools down and becomes solid, that is how igneous rocks are created. Magma is hot melted rock deep in the earth’s crust where all of the temperatures are high. Molten rock on the earth’s surface is lava. If rocks are cooled below the earths surface that is called intrusive rock. An example of an intrusive rock is Granite that forms very slowly, deep inside the earth. If a rock cools on earth’s surface is called extrusive rock. Volcanic rocks such as obsidian, pumice, and scoria, are extrusive rocks. Igneous rocks can cool slowly or quickly.
Metamorphic rocks
A rock that has many layers and with a lot of shiny mica particles, might be a metamorphic rock. When heat, pressure, or fluids change one type of rock to another, is how metamorphic rocks are formed. Sedimentary and igneous rocks can also be parts of metamorphic rocks. Below the surface of the earth is where metamorphic rocks are always formed where heat and pressure is very high. The rock that has been changed into a metamorphic rock is called the parent rock. One parent rock can be changed into many different metamorphic rocks depending on the heat and pressure applied. For example, a sedimentary rock called shale, can change into slate. Metamorphic rocks that have layers are said to be foliated. Foliated means having thin, leaf-like layers. Some metamorphic rocks do not have layers. An example of a rock without layers is marble and quartzite. A example of a mineral with layers is gneiss. Metamorphic rocks that do not have layers are said to be non-foliated.
Sedimentary rocks
Sedimentary rocks are made from sediments and or by chemical reactions. Sediments are loose material, such as bits of rocks, minerals, plants, and animals. Where the larger, heavier fragments settle first in oceans and lakes, is often where sedimentary rocks are made. Each layer of sediment is squeezed together by the weight above it. The process of squeezing together layers of sediment is called compaction. As water soaks into the rocks, the minerals in some rocks dissolve. The dissolved minerals form a natural cement that sticks that sticks the larger pieces of sediment together. Pieces of sediment that are held together by another material is called cementation. There are many sedimentary rock that are formed by compaction and cementation.
Why are there three types of rocks?
There are three types of rocks called sedimentary, metamorohic and igneous. Igneous rocks are formed inside and outside of the earth. Sedimentary rocks are formed outside of the earth and metamorphic rocks are formed inside of the earth. When rocks are formed inside of the earth is is called a intrusive rock. When an intrusive rock is formed it is always made of magma because magma is always inside of the earth. When a rock is formed outside of the earth it is called a extrusive rock. When an extrusive rock is formed it is always made of lava because when a volcano erupts, it erupts magma from inside the earth that has changed into lava when it has come out of the volcano.