Which of the following are considered main components of a geologic map?

A geologic map serves as a vital tool for understanding the distribution and relationship of different rock units and geological features in a specific area. The main components of a geologic map include rock units, which represent different types of geological materials and their ages; structural features, which indicate the orientation and arrangement of rocks, such as faults and folds; symbols that provide standardized representations for various features on the map; and a legend that explains what each symbol signifies.

Rock units are essential because they help identify the composition of the earth's crust in various locations, allowing geologists to interpret the geological history and processes that shaped the area. Structural features reveal the forces that have acted on the rocks over time, while the symbols and legend are crucial for clarity and understanding, ensuring that anyone reading the map can accurately decode the information presented.

Other options include components that are less relevant to the specific focus of a geologic map. For instance, concepts like land use and vegetation types pertain more to ecological or urban planning maps rather than geological interpretations.