Final answer:
An unconformity is a surface that represents a break in the rock record caused by erosion or nondeposition. There are different types of unconformities, including disconformities and nonconformities.
Step-by-step explanation:
An unconformity is a surface that represents a break in the rock record caused by erosion or nondeposition. It is a buried erosional or non-depositional surface separating two rocks or strata of different ages, indicating that sediment deposition was not continuous. There are different types of unconformities, including disconformities, which form when horizontal layers of sedimentary rock are deposited in a shallow marine environment and then eroded, creating a large age gap between the rocks above and below; and nonconformities, which form when igneous or metamorphic bedrock is eroded and then sedimentary rocks are deposited