Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
층위학은 지층의 형성과 변화를 연구하는 학문입니다.Cheungwihak-eun jichung-ui hyeongseong-gwa byeonhwa-reul yeongu-haneun hakmun-imnida.Stratigraphy is the study of the formation and changes of strata.