Describe two ways in which batholiths intrude into existing rock.

Batholiths are large bodies of intrusive igneous rock that form deep within the Earth's crust. They are typically formed from magma that cools slowly, allowing the individual mineral crystals within the rock to grow large. Batholiths can be exposed at the Earth's surface through erosion and uplift processes. Now, let's discuss two ways in which batholiths intrude into existing rock.

Assimilation is the process through which a batholith intrudes into existing rock by incorporating the surrounding host rock into its magma. As the magma intrudes into the crust, it encounters the host rock and heats it, causing the host rock to melt partially or completely. The molten host rock then mixes with the magma, altering its composition. This process continues as the magma moves through the crust, bringing in more host rock and causing more assimilation. The final batholith will contain a mix of minerals from both the original magma and the host rock.

Stoping is another process through which batholiths intrude into existing rock by breaking off pieces of the host rock and incorporating them into the intruding magma. As the magma pushes its way through the crust, it creates pressure on the surrounding host rock. The pressure can cause the host rock to fracture and break off, forming large blocks or smaller fragments. These pieces of host rock then fall into the magma and become part of the batholith as they are assimilated. This process leads to an irregularly shaped intrusion as the host rock is "stopped" or engulfed by the batholith. In conclusion, batholiths intrude into existing rock through two main processes: assimilation, which involves the melting and incorporation of host rock into the magma, and stoping, which involves the breaking off and engulfment of the host rock by the magma. Both processes contribute to the formation and growth of batholiths within the Earth's crust.