What is the Difference Between Lithology and Geology

The main difference between lithology and geology is that lithology describes the properties of a unit of rocks whereas geology describes the occurrence and changing of rock on Earth’s crust over a long time period.

Lithology and geology are branches of Earth sciences that are important in describing the properties, occurrence and changes of rocks on the Earth’s crust. Therefore, these are sciences related to solid Earth.

Key Areas Covered

1. What is Lithology 
     – Definition, Characteristics
2. What is Geology
     – Definition, Characteristics
3. What is the Difference Between Lithology and Geology
     – Comparison of Key Differences

Key Terms

Earth Science, Lithology, Geology, Rocks

What is Lithology

Lithology is a branch of earth sciences that describes the properties of a unit of a rock on Earth’s crust. Here, the rocks are analyzed in visible outcrop, in core samples, or using low magnification in light microscopes. Therefore, the features of rocks that can be analyzed using these methods include the colour, texture, grain size, and composition. Lithology refers to the detailed description of these characteristics or a summary of the properties of the rock.  

According to lithology, there are three major types of rocks: sedimentary rocks, igneous rocks, and metamorphic rocks. Sedimentary rocks form from the accumulation and deposition of small particles followed by cementation with minerals and organic particles. Igneous rocks form from the solidification and deposition of magma and lava. Metamorphic rocks, on the other hand, form from the change of an existing rock type into another type via a physical process called metamorphism.

Lithology mainly focuses on the grain size of rocks when describing them. For example, large grains sizes typically indicate intrusive igneous rocks while small grain sizes indicate extrusive igneous rocks. Colour is another important feature in a rock. For example, igneous rocks always have a very dark (mostly black) colour.

In lithology, the texture of a rock indicates the relationship between the individual grains or clasts that make up the rock. For example, the texture of sedimentary rocks includes the degree of sorting, grading, shape, and roundness of clasts. The texture of metamorphic rocks includes the timing of growth of large metamorphic minerals relative to a phase of deformation. Moreover, the texture of igneous rocks includes the size of the mineral grains. 

What is Geology

Geology is a type of earth science that describes the properties of solid Earth. This includes the composition of rocks and the changes that happen to a rock over time. This field also includes the study of solid features of any terrestrial planet or natural satellites – e.g. Mars, Moon, etc. The branch of geology considerably overlaps with other earth sciences such as hydrology, and atmospheric sciences.

Furthermore, geology explains the structure of the Earth below its surface, including the processes that changed the early Earth into this structure. Geology also has tools that are useful in determining the age of rocks and their history. Therefore, we can describe the history of the Earth as a whole.

The geological materials on Earth fall into two categories as rock and unlithified materials. However, the majority of the research studies are carried out regarding rocks. In addition to rocks, geologists also consider unlithified material which comes from recent deposits. For example, magma and lava are unlithified materials.

Difference Between Lithology and Geology

Definition

Lithology is a branch of earth sciences that describes the properties of a unit of a rock on Earth’s crust, while geology is a type of earth science that describes the properties of solid Earth.

Categorization

Lithology is a branch of geology while geography is a branch of Earth sciences.

Description

While lithography involves detailed description of the characteristics or a summary of the properties of the rock, geography describes the composition of rocks and unlithified materials and the changes happen to them over time.

Conclusion

In brief, lithology and geology are branches of Earth sciences that are important in describing the properties, occurrence and changes of rocks on the Earth’s crust. The main difference between lithology and geology is that lithology describes the properties of a unit of rock, whereas geology describes the occurrence and changing of rock on Earth’s crust over a long time period.

Reference:

1. “Lithology – An Overview | Sciencedirect Topics”. Sciencedirect.Com, 2020, Available here.
2. “Lithology”. En.Wikipedia.Org, 2020, Available here.
3. “Geology”. En.Wikipedia.Org, 2020, Available here.

Image Courtesy:

1. “SEUtahStrat” By Matt Affolter (QFL247) (CC BY-SA 3.0) via Commons Wikimedia
2. “Lake Kinney mit Mount Whitehorn” By Florian Fuchs (CC BY 3.0) via Commons Wikimedia