The main difference between batholith and laccolith is that batholith is a large irregular mass of intrusive igneous rock that has melted or forced itself into surrounding strata whereas laccolith is a mass of igneous or volcanic rock found within strata which forces the overlaying strata upwards and forms domes.
Batholith and laccolith are two types of rocks. The suffix –lith in both these terms refer to the meaning “rock”. A rock is a hard material that forms due to the solidification of different materials. Moreover, the three major types of rocks are sedimentary rocks, igneous rocks, and metamorphic rocks.
Key Areas Covered
1. What is Batholith
– Definition, Features, Formation
2. What is Laccolith
– Definition, Features, Formation
3. What is the Difference Between Batholith and Laccolith
– Comparison of Key Differences
Key Terms
Batholith, Laccolith, Rock
What is Batholith
Batholith is a type of rock that is a large mass of intrusive igneous rock. These rocks form from the solidification of magma deep down the Earth’s crust. Moreover, these rocks are made of felsic or intermediate rock types. These rock types include quartz, granite, monazite, diorite, etc.
Batholith rocks appear as uniform structures, but they are rocks with complex histories and compositions. Generally, these rocks contain multiple masses (plutons). There are also bodies of igneous rock with irregular dimensions. The individual plutons are formed from the magma that travels to the Earth’s surface through a zone of partial melting and then solidifies.
Figure 1: Appearance of a Batholith Rock
A batholith rock type forms when many plutons get together to form a granitic rock. A common batholith rock is Sierra Nevada Batholith, in California. It is a continuous granitic formation. Batholith rocks are very large masses that have a large surface area (larger than 100 square kilometres). We call the structures that are smaller than this much surface area as stocks. Usually, the surface of batholith rocks is exposed to air due to erosion that is accelerated by the continental uplifting process. This process can expose rocks that are buried deep down the Earth.
What is Laccolith
Laccolith is a type of rock that appears like sheet-like intrusions that are injected within the layers of sedimentary rocks. These intrusions occur when the pressure of magma is high enough to move the strata of the sedimentary rock upward or to make them folded. This pressure causes the laccolith rock to have a dome or mushroom-like appearance. Generally, the base of this structure is planar.
Figure 2: Small Hills of a Laccolith Rock
Erosion of these rocks can cause them to have small hills, mountains, or a central peak. This is because the magma rocks are highly resistant to weathering. The formation of laccolith rocks takes a little time (about several months) compared to the formation of most other rock types.
Difference Between Batholith and Laccolith
Definition
Batholith is a type of rock which is a large mass of intrusive igneous rock while laccolith is a type of rock that appears as sheet-like intrusions that are injected within the layers of sedimentary rocks.
Occurrence
While batholiths occur as individual intrusive igneous rocks, laccoliths occur as intrusions in sedimentary rocks.
Formation
Moreover, batholiths form when many plutons get together to form a granitic rock while laccoliths form when the pressure of magma is high enough to move the strata of the sedimentary rock upward or to make them folded.
Conclusion
The main difference between batholith and laccolith is that batholith is a large irregular mass of intrusive igneous rock that has melted or forced itself into surrounding strata whereas laccolith is a mass of igneous or volcanic rock found within strata which forces the overlaying strata upwards and forms domes.
Reference:
1. “Batholith.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 29 Jan. 2020, Available here.
2. “Batholith.” Wikipedia, Wikimedia Foundation, 23 Apr. 2020, Available here.
3. “Laccolith.” ScienceDirect Topics, Available here.
4. “Laccolith.” Wikipedia, Wikimedia Foundation, 16 Apr. 2020, Available here.
Image Courtesy:
1. “Yosemite 20 bg 090404” By Jon Sullivan – [1] (Public Domain) via Commons Wikimedia
2. “NotchPeak” By Qfl247 at English Wikipedia (CC BY-SA 3.0) via Commons Wikimedia
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