This study is aimed at analyzing a geography text in terms of transitivity, mood, theme, and cohesion to see how it is organized lexically, grammatically and semantically using systemic functional grammar as the theoretical framework. To fulfill this objective, the author analyzed the ESP text "Acid Precipitation - A Human Impact on the Earth System". After a thorough study, it can be concluded that material and relational processes are the two main processes in this geography text. They are account for 50 and 37 percent irrespectively of the total clauses in the text. Besides, most of the mood patterns in the text are declarative, which is the typicality of a description. Furthermore, most of the thematic patterns in the clauses are unmarked themes. In the text, some cohesive devices are also used. They include conjunctives, references, repetitions, synonyms, hyponyms and meronyms. The findings of the analysis can partly contribute to the understanding of scientific texts, especially geography ones.