There can be several kinds of rocks for kids. The earth’s crust is made up of rocks and we see them lying on the surface or they make up the mountains. Rocks and stones occur in nature as solids and are made up of minerals. As a kid, it can be a really fun activity to collect rocks and it can be a great learning opportunity. There are many different kinds of rocks. They come in different sizes, shapes and colors however the main difference between the rocks is the way in which they were formed. This is the main classification method used by geologists.
Going by this classification method, we can divide the rocks into three main categories; the igneous, sedimentary and metamorphic rocks. As a rock collector, it is a good practice to classify your rocks and place them in categories so that it becomes easier for you to recognize them.
Igneous rocks are the kind of rocks which are made over a period of time due to cooling and solidification of magma and lava. When pressure builds up inside Earth, it spews out molten rocks in the form of lava. This lava then cools down and solidifies to form rocks which are called igneous rocks. Different kinds of rocks are formed depending on different cooling rates. For example if the cooling rate is really fast, then the grains formed are really small. If the cooling rate is slow then coarse grained rocks are formed.
Usually fast cooling rates are observed in extrusive rocks which form on the surface of Earth. The intrusive igneous rocks or the one which form within the surface of Earth cool down slowly because temperature within is higher than surface temperature. The ages of igneous rocks can be determined from radio spectrometry. The rocks also give us important information. For example, in a basalt rock the striations tell us about the direction of lava flow. Some important igneous rocks are obsidian (glass formed from lava), granite, basalt, gabbro and pumice.
Sedimentary rocks are the second most important kind of rocks which form due to a process known as sedimentation in which mineral or dust particles settle down at bottom of solution or on the surface of Earth. It gives us important information about history as archaeological artifacts are often buried in the sediments.
This kind of rock is basically formed due to attraction of eroded particles or because compressive forces act on them to form a rock. Some important sedimentary rocks are shale, sandstones and mudrocks.
As the name suggests, this kind of rocks is formed due to transformation of the existing rock types hence known as ‘metamorphic rocks ‘. They can be formed from old igneous, sedimentary and even metamorphic rocks when they are subjected to intense heat and pressure. This causes a change in the chemical and physical structure of the rock. Some common metamorphic rocks are marble, quartzite, slate, schist and gneiss. This is one among the most preferred kinds of rocks for kids.
Kids need some kind of activity in the summers and it is a great activity for them to collect rocks and know about the geology of their planet! These all are the kinds of rocks for kids.