Classification of Rocks and Soil Identification

There are 3 specific types of rocks: Igneous, Sedimentary and Metamorphic rocks. In this lab, these three different rocks will be exhibited through the process that forms them and show how they look as a result.

Igneous Rocks

Igneous rocks are crystalline solids which form directly from the cooling of magma. this is called an exothermic process, or when heat leaves the substance. As it cools, it turns from hot magma to cool solid rock. 

Even the Earth's outer surface is made from igneous rock, as it is hotter the closer it is to the Earth's core.

Obsidian Rock

This type of rock is a volcanic glass naturally formed from magma. It has a sleek black look to it  Below is a picture. 

Sedimentary Rocks

These rocks form from a thin layer that covers the Earth's igneous crust. This layer consists of debris from different layers of loose sediment that get compacted and cemented together. There are three different types of sedimentary rocks: 

Clastic- 

form from little pieces of broken up rock which have piled up and been "lithified" by compaction and cementation.

Chemical-

form when standing water evaporates, leaving dissolved minerals behind.

Organic-

form from  any accumulation of sedimentary debris caused by organic processes.

Shale 

These rocks are classified as clastic. It is composed of mud that is a mix of clay flakes and tiny fragments of specifically quartz and calcite. Below is a picture.

Metamorphic Rocks

Based on the origin of the name, any rock can be metamorphic. "meta" means "change" and "morph" means "from". In order for the process to take place, a rock must composed of minerals and be moved into an unstable environment that causes it change. Ultimately, it would need to be buried deep enough where pressure and heat are more crucial and cause the rock to break down. Then, it will cool and reform as it surfaces.

Gneiss

This rock is formed by  regional metamorphic processes based upon region  from preexisting formations that were originally either igneous or sedimentary rocks. It contains foliations, containing alternating lighter and darker bands, or gneissic bands. A photo is shown below.

To learn more about rocks, click here.

The characteristics of these rocks and where they were formed from can be identified through the soil triangle. These different types of soils can be defined in the 12 soil orders of the world.

Soil Triangle

Soil Orders

Soil Orders (Original size for a better visual)