What are geologic maps and how are they used? Objective Students will learn what geologic maps are used for and how to design one. Using Arthur Lakes’ 1878 watercolor map of the Florissant valley as a reference, students will create their own watercolor map of the Florissant valley. Students will also include a legend in their map to provide descriptions of their colors, a scale, and a north arrow. Background Geologic maps depict geological features and assist geologists in identifying rocks in the field. Rock units are illustrated on geologic maps by color and/or symbols to indicate where the Duration: 60 Minutes.