Aka: Abnormal Coronary Arteries, Abnormal Coronary Artery, Coronary Artery Abnormalities, Congenital Anomaly of Coronary Artery, Anomalous Coronary Vessel.
Unconformities. Unconformities are gaps in the geologic record that may indicate episodes of crustal deformation, erosion, and sea level variations. They are a feature of stratified rocks, and are therefore usually found in sediments (but may also occur in stratified volcanics).
The Great Unconformity refers to a gap in the strata of the Grand Canyon observed by John Wesley Powell in 1869. The gap Wesley discovered is between sandstone that dates around 500 million years in age and igneous and metamorphic rock that is about 1700 million years old.