Among the many staple figures found in introductory human or cultural geography textbooks, language maps are consistently used as illustrations for lessons on linguistic and cultural diversity. For some students, the single image of a language map can convey ideas of cultural distribution and migration that may outpace the effectiveness of written passages on the same topics. However, language maps cannot perfectly capture the true linguistic environment of a study area. They require considerable generalization given the fluidity of languages. Language maps are simply generalized snapshots in time of a variable that is in constant change. Further, some of these maps can be confusing to interpret. When no information is provided about data or design decisions made in producing the map, the message presented to users can be vague or even conflicting. These confusing figures, often found in educational contexts, generated our curiosity about language map construction.
Unlike other disciplines with ongoing discussions of standards and guidelines for mapping (e.g. geology), an important revelation about language mapping is that there are no established standards or rules to guide language map construction (Kirk, Sanderson, and Widdowson 1985; Ambrose and Williams 1991; Williams 1996). This absence of common conventions is especially problematic since language mapping is used in many disciplines including geography, linguistics, and anthropology. With researchers from diverse disciplines approaching the task of language mapping with their widely varying expertise, some construction guidance would be useful to produce a level of consistency within the map genre. Further, the lack of guidelines does not indicate a lack of difficulty in producing language maps. Language is dynamic and often intangible, which are not qualities that make cartographic representation an easy assignment. In fact, the translation from a language dataset to a language map produces a number of conceptual cartographic issues that can result in misrepresenting the language reality. The vector format predominates in language mapping although the use of discrete points, lines, and polygons is not a natural fit to the nature of language. Language is described in the literature as fluid and continuous, characteristics that oppose the qualities inherent in vector mapping. Determining and depicting language boundaries as solid lines does not reflect the existence of language transition zones described by researchers. Similarly, the common trend of showing only one language per place does not convey the reality of linguistic diversity and plurality, which is a common feature of contemporary society. For reasons of confidentiality, language data are frequently aggregated when used for mapping purposes. To achieve this, political mapping units such as countries or states are sometimes used as language mapping units although language may not naturally function at these scales. All of these issues, related to making language fit the mold of a vector environment, can compound to thoroughly disguise the real nature of the language landscape.
With a frequent language loss and language movement occurring in our world today, language maps will continue to be useful tools for both research and educational purposes. Fortunately, we now have new technology available to tackle some of their construction problems. Geographic information systems (GIS) allow for increased flexibility in data storage, manipulation, analysis, and display that far outpaces previous technology. The introduction of GIS can breathe new life into the task of language mapping, renewing it as a field ripe for research. However, where do we begin? What types of maps and design elements do language maps typically feature? Without commonly held conventions, it is unclear what symbology strategies are used most often in language mapping and therefore what strategies we should review and potentially improve. Only Ambrose and Williams (1991) attempt to provide a general typology of language mapping trends; however, their symbology summary is not accompanied by any quantification of formal map observations. Over twenty years after the publication of Ambrose and Williams (1991), we follow up on their work by applying their symbology typology in a quantified map survey to document the characteristics of language maps. We characterize language-mapping practices by surveying the cartographic qualities of existing language maps, extracting patterns of language map construction from the trends observed in a sample collection of maps. This map survey addresses two questions: (1) what are the common cartographic characteristics of language maps; and (2) does the existing general symbology typology of Ambrose and Williams (1991) adequately capture language mapping in practice?
Language mapping is not a new endeavor. Publication of linguistic atlases created from extensive survey research began most notably in Europe in the late nineteenth century with works focused on Germany and France (Crystal 1997). The undertaking of such large, linguistic surveys created many challenges long before reaching the actual mapping stage of the project. Researchers had to choose representative communities and individuals for their samples; compile questionnaires that captured appropriate features; develop fieldwork methods and train fieldworkers; verify data; and, of course, obtain financing (Kurath 1931 ; Menner 1933; Mackey 1988; Williams 1996). Numerous researchers provide detailed documentation of language mapping and linguistic atlas history as well as thorough descriptions of individual atlas projects (Kahane 1941; O'Cain 1979; McDavid et al. 1986; Pederson 1993; Crystal 1997: Wikle and Bailey 2010).
Language maps as a whole are a thematic map genre that features great variety in both the use of different symbology options and the display of different data variables. Both Ambrose and Williams (1991) and Ormeling (1992) provide general descriptions of symbology types used for language maps. Ormeling (1992) discusses the use of chorochromatic, choropleth, isoline, and flow line maps for linguistic data as well as proportional and qualitative symbols. Ambrose and Williams (1991) provide a visual aid for their symbology summary and categorize mapping techniques by the use of points, lines, and polygons (Figure 1). For the most part, these language mapping overviews reiterate commonly known cartographic techniques. Only one symbology type, the use of isoglosses, is unique to language maps. Unlike the isoline, which connects points of equal value (e.g. elevation contours; Gregory et al. 2009), an isogloss is a boundary line that defines areas where the use of a particular linguistic feature is different (Finch 2000; From kin and Rodman 2002; Crystal 2005). An isogloss may note areas that differ in the pronunciation of a word or that use a different word for a specific item. When multiple isoglosses spatially coincide or bundle up, it can potentially indicate the location of a dialect boundary (Kurath 1931; Wagner 1958; Masica 1976; Breton 1991; Finch 2000). Concerning variables, there is no shortage of displayed data variety for language maps. Linguistic atlases feature the spatial distribution of internal or sublanguage characteristics such as pronunciation, vocabulary, and structural features. Conversely, other maps depict characteristics that apply to languages as a whole such as the distribution of language families, language areas, or official languages, as well as speaker percentages or rates of bilingualism. While the terms "language map" and "linguistic map" are used interchangeably in the literature, we use the general term "language map" in this article to refer to any map that features some kind of language data as its focus.
As mentioned above, language mapping is still without a set of standards for map construction (Kirk, Sanderson, and Widdowson 1985; Ambrose and Williams 1991; Williams 1996). This absence of guidelines, however, has not decreased the presence of language maps, especially those found in textbooks. Recent editions of college-level introductory geography textbooks still feature one or more language maps within their covers (e.g. Fouberg, Murphy, and de Blij 2009; Dahlman, Renwick, and Bergman 2010; Getis et al. 2010; Knox and Marston 2010; Marston et al. 2010; Rubenstein 2010). Although the commonly featured map of the world's languages is an intentionally generalized depiction of language distribution, Mackey (1988) states that it is oversimplified while Brougham (1986) finds the structure outdated. The main issues that arise in language mapping are related to the use of a vector environment. Both Ormeling (1992) and Ambrose and Williams (1991) predominantly speak of vector symbology types using points, lines, and polygons in their discussions of language-mapping symbology. While the vector format prevails in language mapping, it contrasts strongly with the continuous nature of its subject (Breton 1991). The result of this conflict is the loss of a key characteristic of the language reality when translated to its cartographic representation. The use of a vector format for language map construction creates three main issues: boundary representation, choice of mapping units, and display of linguistic plurality.
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The placement and depiction of boundaries can be difficult for almost any mapped variable; however, boundaries on language maps pose their own additional challenges. The location of lines on language maps can result from arbitrary decisions (Macaulay 1985). In the case of isogloss mapping in particular, lines are drawn based on researchers' decisions about the location of observed data points (Kirk, Sanderson, and Widdowson 1985; Ormeling 1992). Given this interpretive aspect of isogloss depiction, the same dataset used by...