Geology is an interesting subject, holds many terms that have quite similar meanings yet are completely different. This happens with almost every branch of science too, we call it the difference of literature. Joints and faults are the types of fractures or cracks in a rock due to weathering of rocks for a long period.
In the language of science and the language of commoners, there lies a difference of understanding. Therefore, the difference between joints and faults might not be notable to the commoners but in terms of geology, they hold vast differences amongst themselves.
Joints vs Faults
The main difference between joints and faults is that joints are small in size and don’t cause any movement in the parts of the rocks whereas faults are considerably big and can be affected by lateral tectonic movements, plus the way both are constructed are quite different in notable manners.
When a rock is pushed beyond its breaking point due to natural strains like wind, water, and earth flow, joints develop. This occurs because the buildup of dirt on rock formations increases their bulk, causing them to break apart. But, above and beyond these characteristics, many individuals are concerned about the threat that these fissures may offer to human civilization. Some joints may also be the reason for the huge hills and mountains we see in the present day! Fissures like horizontal stripes are the appearance of a typical joint fracture.
Faults, on the other hand, are quite scary, to be honest. Faults are the faults on the surface of the rock, they are formed when a rock is shattered and the fault lines can sometimes extend to miles and kilometers!
Surprising facts about fault lines is that the faults had been created back in the times when the earth was “young”, and after the long process of evolution for millions of years dirt and dust have covered these fault lines. As a result, whenever the tectonic plates move, the fault lines increase the intensity of earthquakes exponentially making them scary and dangerous for human beings and civilizations.
Table of Comparison Between Joints and Faults
| Parameters of Comparison | Joints | Faults |
| Definition | These are fractures over rocks caused by natural phenomena that result in continuous strain on rocks and hence fissures appear on the surface. | These are hairline or sectional fractures on the rocks caused by tectonic movements. |
| Appearance | Long and horizontal or vertical fissures. Sometimes it resembles ‘flow’ patterns. | Cracks and crevices on the surface of rocks, covered by accumulated dust and dirt for years. |
| Cause | Rocks reach the breaking point due to strenuous weather conditions and develop these fissures. | Caused by rigorous tectonic movements and crackings. |
| Size | Smaller and compact in size. Usually, they are like long stripes. | Can range up to miles and might be as big as a country sometimes! |
| Movement | No movement occurs. | Movement occurs when tectonic plates move and can cause natural disasters like earthquakes and tsunamis. |
What is Joints?
When we take a glance into the world of rocks and earth, geology exhibits a commonly used geological term for weathering of rocks. Joint is the result of this weathering, it’s simply a fracture caused on the rock due to strenuous weather conditions like water flow and wind and temperature fluctuations. These are static and do not cause any harm, unlike the faults.
Because they do not entirely divide rock formations, joints have very little or no mobility. Joints are comparatively compact and lesser in size than faults and may be found in nearly every type of rock formation. Very commonly found on sedimentary and red sand rocks because of the formation process of these rocks.
Joints are among the most common geologic features, appearing in almost every rock exposure. They come in a variety of shapes, sizes, and arrangements, and they may be found in a variety of tectonic settings. The exact source of the pressures that produced certain joints and related joint sets is sometimes vague, imprecise, and even contentious.
What is Faults?
Just like joints, faults are also the result of weathering in rocks. Hair-line fractures and cracks over the surface of rocks, however, faults are much more fatal than the harmless joints. Faults are distinctly specified because they are susceptible to lateral displacement induced by tectonic forces under the Earth’s surface.
Faults are also known as “Nature’s Movers” because of their mobile nature, they are the primary cause of earthquakes and tsunamis. The continuous movement beneath the Earth’s crust causes faults. Faults split rock formations, making them prone to earthquakes. The movement of tectonic plates directly affects the fault fissures of these huge rocks and as a result, the shocks transfer from the rocks to the civilization built upon them.
A fault plane is a flat plane that depicts a fault’s fracture rate concerning time and the type of surface. A fault trace, also known as a fault line, is a location on the surface where the fault may be viewed or mapped. A fault trace is also the line that is often used to indicate a fault on geologic maps. These terminologies vastly help geologists to determine the age and duration of the faults in the rock.
Main Differences Between Joints and Faults
- Joints are smaller and compact than faults.
- Joints are caused by strenuous conditions of nature that push the rocks to their limits, whereas faults are caused by tectonic movements.
- Joints are immobile irrespective of the tectonic movements whereas faults are mobile and can cause tectonic shocks too.
- Joints cannot cause any natural disasters but faults are the primary reasons for tsunamis and earthquakes.
- Joints are of three types; Systematic, non-systematic, and columnar whereas, faults are of six types; strike-slip, dip-slip, oblique, listric, ring, and synthetic faults.
Conclusion
Fractures or discontinuities in the Earth’s crust are classed as both joints and faults. The way a joint and a defect are formed is what distinguishes them. The continuous movement beneath the Earth’s crust causes faults. Faults separate rock formations, making them prone to earthquakes.
Both types of fissures are a result of weathering of rocks caused millions of years ago from now. Joints being immobile and harmless have carved themselves into hills and small crevices on the surface of Earth whereas, there are yet many undiscovered fault-lines on the surface of Earth hidden under accumulated dirt. Eventually, they’ll be discovered when the tectonic plates show any significant movements.
References
- https://www.britannica.com/science/fault-geology
- https://www.encyclopedia.com/earth-and-environment/geology-and-oceanography/geology-and-oceanography/joint-geology