Exogenic Force: Physical Weathering

Introduction

Force is an external agent equipped for changing the condition of rest or movement of a specific body. It has a magnitude and a direction. The direction towards which the force is applied is known as the direction of the force and the use of force where power is applied. There are two principal kinds of force:

Exogenic Force: The forces which get their strength from the surface of the earth or begin in the earth’s atmosphere are called exogenic forces. The action of exogenic forces results in wearing down and hence they are considered as land wearing forces. Exogenic forces are external forces that are acting on the surface of the earth through many processes like weathering, erosion, deposition etc.

Endogenic forces: These forces are the tension inside the earth, otherwise called inward powers. Such interior powers add to vertical and even movements and lead to subsidence, land upliftment, volcanism, blaming, collapsing, quakes, and so on. Volcanism, collapsing, and blaming are the key instruments associated with this. 

Weathering: Weathering is the breakdown of rocks at the earth’s surface, by the activity of water, change in temperature, and organic movement. There are three sorts of weathering: Physical, Chemical and Biological. 

1. Physical Weathering: Physical Weathering is the cycle that splits rocks without changing their chemical composition. Physical weathering includes the breakdown of rocks and soils through the mechanical impacts of hotness, water, ice, or different agents.
2. Chemical Weathering: Chemical weathering involves the chemical reaction of water, atmospheric gases.
3.  Biological Weathering: Biological weathering is the debilitating and resulting deterioration of rock by plants, creatures and organisms.

Exogenic Processes: The processes which occur on the earth’s surface due to the influence of exogenic forces are called exogenic processes or exogenic geomorphic processes. Weathering, mass wastage, erosion, and deposition are the fundamental exogenic processes. All the exogenic cycles are covered under an overall term-denudation, which means peel off or uncovers. The elements of nature capable of doing these exogenic processes are termed geomorphic agents (or exogenic geomorphic agents). E.g. the wind, water, waves etc.

Note: An interaction is a power applied on earth materials influencing something similar. An agent is a mobile medium (like running water, moving ice, winds, waves etc) that removes, transports and deposits earth materials.

Geomorphic processes and geomorphic agents especially exogenic, unless stated separately, are one and the same.

Gravity and gradients are the two things that make these agents mobile. All the movements are either within the earth or on the surface of the earth. These occur due to gradients from more elevated levels to bring down levels, from high strain to low tension and so forth 

The exogenic forces get their energy from the environment controlled by definitive energy from the sun and the angle made by structural elements. So, we can say that slants on the earth surface are fundamentally made by structural factors or earth developments due to endogenic forces. We realize that power applied per unit region is called pressure. Stress is delivered in a strong way by pushing or pulling. The gravitational force follows up on all earth materials having a slanting surface and will in general create the development of issues in the down-incline direction. This makes pressure and actuates disfigurement to the particles.

Physical Weathering

Physical Weathering takes place when rock is broken, but no chemical changes take place. Water is a major cause of physical weathering. This can take the form of oxidation (by the air) or dissolving (by water and other chemicals in the water, such as sulphuric acid from acid rain). Physical weathering happens, especially in places where there is little soil and few plants grow, such as in mountain regions and hot deserts. It occurs either through repeated melting and freezing of water (mountains and tundra) or through the expansion and contraction of the surface layer of rocks that are baked by the sun (hot deserts).

Types of Physical weathering

The various categories of physical/mechanical weathering are determined by natural processes and physical forces. They include

Thermal Pressure

Changes in temperature add to the expansion and contraction of rocks. At the point when the temperature of the rock increases, the rock extends and when the temperature of the rocks diminishes, the rock compresses. Since the external surface is more uncovered than the inward surface, there is lopsided withdrawal and development of the rock’s constituent minerals. This interaction brings about actual pressure, likewise named as thermal pressure, which can break or split the rock up.

Freeze-thaw

Freeze-thaw likewise alludes to ice chatting or ice weathering. At the point when water enters the stones through the pores and breaks, it freezes. When the frozen water is inside the stones, it extends by around 10% in this way opening the breaks somewhat more extensive. The pressure acting inside the stones is assessed at 30,000 pounds for each square inch at – 7.6 °F.

Release of Pressure or Exfoliation

When the overlying stone materials are stripped by abrasion or other disintegration processes, it leads to breaking, cracks and extension of the basic rocks parallel to the surface. This makes the underlying rocks release the pressure in them. Over time, sheets of rock separate from the stripped rocks and break into smaller pieces along with the fractures through a process termed exfoliation. Exfoliation happens when cracks form parallel to the land surface as an impact of the pressure discharge during abrasion, the retreat of an overlying icy mass, or rock elevations.

Salt-crystal Growth or Salt Weathering

Salt-crystal development is likewise alluded to as salt weathering or haloclasty. It happens when saline solutions enter the rock pores or break and dissipate, leaving behind salt crystals. The gathered salts crystals are warmed up when natural temperatures are high, and they extend along these lines delivering pressure on the rock, making the rocks break down.

Plant Growth and Animal Action

Trees and other plants can erode rocks when their underlying foundations infiltrate the cracks in the rocks. As the roots increase in size, they apply pressure on rocks and make the cracks more extensive and more profound, in the end splitting the rocks up. Tunneling creatures like moles, squirrels and bunnies slacken and deteriorate the rocks in the soil.

Abrasion

Abrasion is the wearing out or scrapping of rock particles by friction due to water, wind or ice. The proceeded weakness to these components progressively separates the uncovered surfaces of the rocks. It is the activity on the rocks by wind, ice, rain, and waves combined.

Processes of Physical/Mechanical Weathering

Mechanical or physical weathering is a process that constantly takes place since nature influences it. The process usually happens near the surface of the earth influenced by wind, water, and temperature.

Wind

The physical forces of wind act on the loose rocks, leaving them sculptured and denudated. Wind forces carry small particles and rocks that collide with the rocks, in turn, wearing them away. The forces of wind on physical/mechanical weathering are common in sandstorms in deserts.

Water and Glacial Materials

Water gets into the rocks and once inside the rocks and freezes. The frozen water extends and makes the rocks debilitate and enlarges the breaks. Over the long haul, the bigger rocks are broken into more modest sections. Moving ice in frigid regions additionally washes away stone parts and breaks them down into more modest pieces as the rocks cooperate with the forces and pressure of the frozen materials.

Temperature Fluctuations

Change in temperature adds to thermal stress. This is the contraction and expansion impact on the rocks as a result of temperature changes. Because of the lopsided contraction and expansion, the rocks break and deteriorate into more modest pieces. In the long run, these cycles make the rock break down into finer and finer particles.

Conclusion 

Exogenic processes play an important role in the formation of relief and create a variety of landscapes. Exogenic (Exogenetic) processes are a direct result of stress-induced in earth materials due to various forces that come into existence due to the sun’s heat.

Weathering results in the “disintegration of rocks”, that forms the components that lead to the formation of the soil, by the addition of these components to the topsoil.