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Title: Angular Unconformities and Nonconformities.
Caption: This animation has two parts. The first part shows the formation of an angular unconformity that begins with the deposition of sediment layers in an aqueous environment. Subsequent mountain-building processes fold and uplift the sedimentary rock layers. Erosion processes remove the upper portions, revealing bands of different types of sedimentary rocks. Later deposits of sediments create new layers of sedimentary rocks over the angular unconformity. The second part shows the formation of a nonconformity which begins with a large body of intrusive igneous rock exposed at the surface through a combination of uplift and erosion. At a later time the rock body is covered by layers of sedimentary rocks, leading to the inclusion of pieces of the rock body in the lowest layer of sedimentary rock.
Keywords: geologic time scale, relative dating, angular unconformity, angular unconformities, folds, erosion, subsidence, nonconformity, nonconformities