Science Olympiad Dynamic Planet Practice Test

What term describes a deposit of hardened magma in a volcano's pipe?

1. dike

2. sill

3. batholith

4. magma chamber

The correct answer is: dike

The correct term for a deposit of hardened magma in a volcano's pipe is "dike." A dike forms when magma moves upward through cracks in the surrounding rock, solidifying as it cools. When the magma hardens inside the vertical or nearly vertical cracks that make up a volcano's conduit, it can create a dike that often cuts across pre-existing rock layers. In contrast, a sill is a horizontal layer of solidified magma that intrudes between existing layers of rock, rather than filling a vertical space. A batholith is a large mass of igneous rock that has cooled and solidified deep within the Earth’s crust and typically extends over a much larger area than a dike. Lastly, a magma chamber is a reservoir of magma located beneath the surface of a volcano, serving as a source of magma during volcanic eruptions but is not specifically the hardened deposit in the conduit itself. Thus, the characteristics of a dike align perfectly with the description of what occurs in a volcano's pipe.