The Earth’s surface is constantly changing. These changes mostly occur in very minute ways which over time accumulates to create the earth’s physical features we observe around us today.
Some of these changes take thousands of years. When you look around and you might see a mountain, river, plateau, valleys, or rock boulders. These all didn’t just appear suddenly rather most of them had a building process like building a house.
Slow Versus Fast Changes to the Surface of the Earth
But how and what causes these changes to the earth’s surface?
There are basically 2 types of changes that occur to the earth’s surface (i) Slow change and (ii) fast change. Fast changes occur through the actions of earthquakes, volcanoes, landslides, etc. while slow change takes time and has a process.
The focus of this article is the slow change since its action is carried out on all parts of the Earth’s surface.
There are two main causes of change to be mentioned here and they are water action and wind action. The processes used by these actions are known as weathering and erosion.
Rainfall (or precipitation) affects erosion and weathering in two ways.
First, precipitation dissolves chemicals in the atmosphere and this solution causes chemical reactions on the various surfaces it falls on thereby weakening those surfaces through this action.
Second, the force of the water onto the Earth’s surface gradually wears it away. This second action becomes more vivid when you study the impact of a drop of water on a sandy surface. The impact dislodges the soils particles from others.
When there is significant amount of rainfall it leads to runoff (water running on the surface) and this runoff has enough force to move loose soil and rick particles to be deposited at a new location. The movement of these particles causes wear and tear on the surface on which they are moved and over time a new landscape evolves.
Water in the form of ice also causes significant landform changes especially in the temperate regions. This occurs through a process called ice or frost wedging.
This essentially means water lodging in cracks and crags of rock get frozen and since frozen water expands it forces the crack to become wider and often times dislodging part of the rock surface.
Wind action follows a an almost similar pattern that is the wind carries particles into the air and those particles are not smooth but ragged in nature therefore as the wind currents drags them and often times slam them against surfaces they tend to wear down the surfaces they come in contact with yielding a new landscape over time.
References and Further Reading
Some Processes that Change the Earth’s Surface – Pacific Northwest National Laboratory
The Forces that Change the Face of the Earth – Ohio State University