Science Olympiad Dynamic Planet Practice Test

What is the definition of a batholith?

1. A volcanic crater

2. A mass of rock formed when a large body of magma cools inside the crust

3. A fissure in the Earth's surface

4. A type of lava flow

The correct answer is: A mass of rock formed when a large body of magma cools inside the crust

A batholith is defined as a significant mass of intrusive igneous rock that forms when a large body of magma cools and solidifies within the Earth's crust. This process typically takes place at considerable depths, resulting in the formation of large rock formations that can extend over hundreds of square kilometers. Batholiths often become exposed at the surface over geological timescales due to erosion, revealing their once-hidden structure. This definition emphasizes the characteristics and processes that contribute to the formation of batholiths, distinguishing them from other geological features. For example, a volcanic crater refers to a depression formed at the summit of a volcano, which is not related to the cooling of magma underground. A fissure involves cracks or fractures in the Earth's surface, often associated with tectonic activity rather than the solidification of large magma bodies. Similarly, a type of lava flow describes the movement of lava that has erupted at the surface, which is fundamentally different from the intrusions that create batholiths. Thus, the correct choice highlights the distinct geological process that defines a batholith.