This chart shows how various kinds of living things appear suddenly in the Cambrian period. It is called the “Cambrian explosion” because of the vast variety of invertebrates that are found in these old rocks, without a trace of ancestors in the older rocks below. Most creationists believe this is an artifact of the environments in which these creatures lived being the first buried by the flood. Smarter, more mobile creatures would escape the flood waters longer and be buried later (higher) in the geologic column.