Answer:
The boundary between geologic units is called a contact.
Step-by-step explanation:
- The geologic units are made up of different kinds of rocks of different ages. These geologic units are separated from each other on the basis of their formation and age.
- Every geologic unit, depending upon its formation and age is assigned a color for the purpose of representation on the map.
- These geologic units share boundaries with each other which for the convenience of map reading are called contacts.