PROJECT: GEOLOGIC MAP Geologic maps are used to show the features in an area, including rock type, folds, and faults. These maps use special
colors, lines, and symbols to illustrate the geography of an area. The most striking feature on a geologic map is color. Each
color represents a different type of rock within a certain age range. Limestone from a certain time period might be colored
green, while limestone from a different time period is colored orange.
Geologic maps also have different types of lines showing contact between rocks and faults. The place where two different
geologic units are found next to each other is called a contact. A depositional contact happens when rock forms above,
under, or beside other rock. Imagine lava from a volcano flows over the ground and then hardens into rock. The place
where the newly formed igneous rock rests on top of existing rock is an example of depositional contact