The purpose of this study was to investigate the inquiry features demonstrated in the inquiry tasks of a high school Earth Science curriculum. One of the most widely used curricula, Holt Earth Science, was chosen for this case study to examine how Earth Science logical reasoning and authentic scientific inquiry were related to one another and how they were reflected in the curriculum. The framework for data collection and analysis used in this case study included logical reasoning, hermeneutics, historical method, and authentic inquiry. Two raters validated the framework's adoption in this study, looking at the content validity and reliability after the training. Each rater rated the sample curriculum independently and compared results to see if or how they agreed and disagreed. This process included questions, discussions, and clarifications about items of each framework. For inquiry tasks, results showed that induction (37.6%) and abduction (47.7%) were mainly used for logical reasoning; in hermeneutics, the process termed "forestructures of understanding" (82.7%) was mainly used, and "recursive reasoning" (12.0%) and the "historical nature of human understanding" (5.3%) were minimally used; and in the historical method, "adhering to the modern principle of uniformitarianism" (48.8%) and "constructing proper taxonomies" (34.2%) were mainly used. However, the curriculum included little use of what is typically represented, in high school Earth Science, as the features of authentic scientific inquiry. These features are "making multiple observations" and "developing theories about mechanisms." This study also analyzed the relationships among three types of logical reasoning and the features of authentic scientific inquiry. Based on these findings on logical reasoning and authentic inquiry features, we discuss the implications for inquiry-based Earth Science curriculum development.