Geologic Contacts

Abstract

Introductory geology classes often include laboratory examination of geologic maps. Almost all undergraduate geology majors are required to do geologic mapping in the field. This article provides these students with an introduction to the ten major types of geologic contacts they are likely to encounter. The ten types of contacts are: 1) bedding planes, 2) diastems, 3) angular unconformities, 4) disconformities, 5) paraconformities, 6) nonconformities, 7) pedologic contacts, 8) faults, 9) intrusive contacts, and 10) extrusive contacts. Each of the contact types is defined and illustrated.