Rock Cycle: Steps Involved In Rock Cycle

Key Concepts

• Rock cycle

Introduction: 

A rock is solid and hard, made up of different minerals. Minerals are naturally occurring, non-living things. Minerals are the main unit of rocks. Generally, rocks are not made up of exact structures or substances that can be explained by any scientific formulas. So, scientists categorize rocks by their method of formation. Mainly there are three types of rocks: Metamorphic rock, igneous rock, and sedimentary rock. Matter such as water, rock, nitrogen, and oxygen are cycled between the environment and living things. To support life, the existing matter should cycle continuously. If matter does not cycle continuously, then Earth cannot support life. 

As matter goes through the cycles of the Earth system, the matter changes, and the Earth’s surface also changes. Some of the processes in this cycle take millions of years. For example, the formation of the mountains. Rock cycle also takes many years. 

     

Rock cycle :

The sequence of processes in which rock changes from one form to another and destroys and again formed by various geological processes is called the rock cycle. All this process takes millions of years. The processes included in the rock cycle are melting, cooling, heating, weathering, erosion, heat, and pressure. Weathering is the process in which rock is broken down into smaller pieces by the effect of wind, water and change in temperature. Erosion is the process in which weathered rock is transported from one place to another by wind, water, ice, or gravity. During the rock cycle, rock forms very deep inside the Earth, sometimes moving, changing, and coming to the surface of the Earth and again returning to the inside of the Earth. The three types of rocks move in the cycle in a different manner. 

Steps involved in the rock cycle :

Rocks may follow various ways in the rock cycle. For example: When a rock is exposed to weathering or erosion, igneous rock changes to sedimentary rock. Under extreme heat conditions, igneous rock changes to metamorphic rock. The pathway that rock follows in the rock cycle is identified by the forces acting on it. 

The three main processes that can change the rock are as follows: 

1. Cooling and crystallization: 

Deep inside the Earth, the temperatures that create magma are very high. Magma is in liquid form. Sometimes, magma that reaches Earth’s surface is called lava. The magma may reach Earth’s surface by a huge explosion through a volcano, or sometimes it comes out slowly through the cracks. As magma cools, crystals grow to form igneous rock. If the magma cools slowly, the crystals grow larger, as it happens if magma remains deep within the Earth. 

When the magma cools rapidly, the crystal’s form will be very small. The formation of crystals from magma is called crystallization. 

2. Weathering and erosion: 

Rocks are worn down by water, wind, ice, and even by plants and animals. Over a period of time, wind, water, and ice can break larger rocks into sediments. The method of breaking down of rocks is called weathering. Moving water, wind, and glaciers carry these pieces of rocks from one place to another. This process is known as erosion. The sediments are deposited and dropped somewhere. This process is known as sedimentation. Then the sediments may be compressed and glued together (Compaction + cementation = Lithification), and this forms a sedimentary rock. All this complete process can take hundreds or thousands of years. 

3. Metamorphism: 

Metamorphism means “to change form”. Within the crust, when the rock gets exposed to extreme conditions of heat and pressure, it undergoes metamorphism. The complete rock does not melt with metamorphism, the rock changes due to extreme conditions of heat and pressure. A metamorphic rock may contain new structures or the texture of a mineral. 

The rock cycle does not have any beginning or end. It keeps on continuing. The various processes involved in the rock cycle take place around hundreds, thousands, or even millions of years. Even though we say rocks are solid and unchanging, they slowly keep on changing all the time by numerous factors. 

Steps to remember in the rock cycle: 

First, lava erupts from a volcano and cools into an igneous rock. Over a period of time, this igneous rock weathered by the effect of wind and rain, which changes the rock into small pieces, are called sediments. These sediments are carried away by wind and water by erosion and get deposited. After deposition, these sediments can be compacted and cemented into sedimentary rock. Over a period, the tectonic activity causes the sedimentary rock to be buried deep in the Earth.  

The pressure and heat from the interior of the Earth change the structure of the rock, turning it into a metamorphic rock. This metamorphic rock continues to be buried even deeper and finally becomes so hot that it melts into magma. The magma then erupts as lava from a volcano and cools as an igneous rock. The cycle starts again. 

Summary

• Rocks are of three types – Igneous rock, Sedimentary rock, Metamorphic rock.
• Crystallization, cooling, weathering, erosion, and metamorphism are the processes that change the rock from one form to another form.
• Rock cycle is created by the change of rock by passing through one or more processes.
• Rock cycle does not stop, it keeps on going, and this supports Earth’s life.