Geology is undergoing changes that could influence its knowledge claims, reportedly becoming more laboratory-based, technology-driven, quantitative, and physics- and chemistry-rich over time. This dissertation uses techniques from information science and linguistics to examine the geologic literature of 1945-2005. It consists of two studies: an examination of the geological literature as an expanding network of related subdisciplines, and an investigation of the linguistic and graphical argumentation strategies within geological journal articles. The first investigation is a large-scale study of topics within articles from 67 geologic journals. Clustering of subdiscipline journals based on titles and keywords reveals six major areas of geology: sedimentology/stratigraphy, oceans/climate, solid-earth, earth-surface, hard-rock, and paleontology. Citation maps reveal similar relationships. Text classification of titles and keywords from general-geology journals reveals that geological research has shifted away from economic geology towards physics- and chemistry-based topics. Geological literature has grown and fragmented ("twigged") over time, sustained in its extreme specialization by the scientific collaborations characteristic of "big science." The second investigation is a survey of linguistic and graphic features within geological journal articles that signal certain types of scientific activity and reasoning. Longitudinal studies show that "classical geology" articles within Geological Society of America Bulletin have become shorter and more graphically dense from 1945-2005. Maps and graphs replace less-efficient text, photographs, and sketches. Linguistic markers reveal increases in formal scientific discourse, specialized vocabulary, and reading difficulty. Studies comparing GSA Bulletin to five subdiscipline journals reveals that, in 2005, GSA Bulletin, AAPG Bulletin, and Journal of Sedimentary Research had similar graphic profiles and presented both field and laboratory data. Ground Water, Journal of Geophysical Research - Solid Earth, and Geochimica et Cosmochimica Acta had more equations, graphs, and numerical-modeling results than the other journals. The dissertation concludes that geology evolves by spawning physics- and chemistry-rich subdisciplines with distinct methodologies. Publishing geologists accommodate increased theoretical rigor, not using classic hallmarks of hard science (e.g., equations), but by mobilizing spatial arguments within an increasingly dense web of linguistic and graphical signs. Substantial differences in topic, methodology, and argumentation between subdisciplines manifest the multifaceted and complex consistution of geology and geologic philosophy