Editing Dialect continuum (section)

== Dialect geography ==
[[File:Aujourd'hui.JPG|thumb|right|Part of map 72 of the ''[[Atlas linguistique de la France]]'', recording local forms meaning "today"]]
Dialectologists record variation across a dialect continuum using maps of various features collected in a [[linguistic atlas]], beginning with an atlas of [[German dialects]] by [[Georg Wenker]] (from 1888), based on a postal survey of schoolmasters. The influential ''[[Atlas linguistique de la France]]'' (1902–10) pioneered the use of a trained fieldworker.{{sfnp|Chambers|Trudgill|1998|pp=15–17}} These atlases typically consist of ''display maps'', each showing local forms of a particular item at the survey locations.{{sfnp|Chambers|Trudgill|1998|p=25}}

Secondary studies may include ''interpretive maps'', showing the areal distribution of various variants.{{sfnp|Chambers|Trudgill|1998|p=25}} A common tool in these maps is an [[isogloss]], a line separating areas where different variants of a particular feature predominate.{{sfnp|Chambers|Trudgill|1998|p=27}}

In a dialect continuum, isoglosses for different features are typically spread out, reflecting the gradual transition between varieties.{{sfnp|Chambers|Trudgill|1998|pp=93–94}} A bundle of coinciding isoglosses indicates a stronger dialect boundary, as might occur at geographical obstacles or long-standing political boundaries.{{sfnp|Chambers|Trudgill|1998|pp=94–95}} In other cases, intersecting isoglosses and more complex patterns are found.{{sfnp|Chambers|Trudgill|1998|pp=91–93}}