The purpose of this study is to investigate in what ways the inquiry task of teaching and learning in earth science textbooks reflect the unique characteristics of earth science inquiry methodology, and how it provides students with opportunities to develop their scientific reasoning skills. This study analyzes a number of inquiry activities in both Korean and American earth science curriculums by using an analysis framework of earth science inquiry methodology. Results suggest that Earth science activities in Korean textbooks appropriately reflect comprehensive earth science methodologies and provide students with more opportunities to develop their earth scientific literacy, while the American curriculum used in the U.S. included only a small number of inquiry-based activities.