Computational Geology 18 Definition and the Concept of Set

Introduction Geology involves measurement, calculation and modeling. Everyone would agree that these are mathematical activities. Geology also involves classification. “In geology we tend to classify everything” (Thomas and Thomas, 2000, p. 571). This observation is certainly borne out by the GeoRef database. On 29 June, 2001, a search under the keyword “classification” brought up 60 papers with publication dates in 2001 and subjects ranging from stratigraphic units (Walsh, 2001) to pyroxenes (Yavuz, 2001). Although we may not think of it as such, classification is a mathematical activity. The mathematics that is relevant to the kind of classification that underpins geologic terminology is included under set theory. The purpose of this and the next column is to illustrate that connection.