There are several types of unconformities, each with its own specific name:
* Angular unconformity: Older rocks are tilted or folded, then eroded, and younger rocks are deposited horizontally on top.
* Disconformity: Younger sedimentary rocks lie on top of older sedimentary rocks, but there's a gap in time represented by the erosion surface.
* Nonconformity: Sedimentary rocks lie directly on top of igneous or metamorphic rocks.
All of these types of unconformities represent a period of erosion or non-deposition, and the missing rock layers can provide important information about the geologic history of an area.
