Dialect continuum

A dialect continuum or dialect chain is a series of language varieties spoken across some geographical area such that neighboring varieties are mutually intelligible, but the differences accumulate over distance so that widely separated varieties may not be. This is a typical occurrence with widely spread languages and language families around the world, when these languages did not spread recently. Some prominent examples include the Indo-Aryan languages across large parts of India, varieties of Arabic across north Africa and southwest Asia, the Turkic languages, the varieties of Chinese, and parts of the Romance, Germanic and Slavic families in Europe. Terms used in older literature include dialect area and L-complex.
Dialect continua typically occur in long-settled agrarian populations, as innovations spread from their various points of origin as waves. In this situation, hierarchical classifications of varieties are impractical. Instead, dialectologists map variation of various language features across a dialect continuum, drawing lines called isoglosses between areas that differ with respect to some feature.
A variety within a dialect continuum may be developed and codified as a standard language, and then serve as an authority for part of the continuum, e.g. within a particular political unit or geographical area.
Since the early 20th century, the increasing dominance of nation-states and their standard languages has been steadily eliminating the nonstandard dialects that comprise dialect continua, making the boundaries ever more abrupt and well-defined.

Dialect geography

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, based on a postal survey of schoolmasters. The influential Atlas linguistique de la France pioneered the use of a trained fieldworker. These atlases typically consist of display maps, each showing local forms of a particular item at the survey locations.
Secondary studies may include interpretive maps, showing the areal distribution of various variants. A common tool in these maps is an isogloss, a line separating areas where different variants of a particular feature predominate.
In a dialect continuum, isoglosses for different features are typically spread out, reflecting the gradual transition between varieties. A bundle of coinciding isoglosses indicates a stronger dialect boundary, as might occur at geographical obstacles or long-standing political boundaries. In other cases, intersecting isoglosses and more complex patterns are found.

Relationship with standard varieties

may be developed and codified at one or more locations in a continuum until they have independent cultural status, a process the German linguist Heinz Kloss called ausbau. Speakers of local varieties typically read and write a related standard variety, use it for official purposes, hear it on radio and television, and consider it the standard form of their speech, so that any standardizing changes in their speech are towards that variety. In such cases the local variety is said to be dependent on, or heteronomous with respect to, the standard variety.
A standard variety together with its dependent varieties is commonly considered a "language", with the dependent varieties called "dialects" of the language, even if the standard is mutually intelligible with another standard from the same continuum. The Scandinavian languages, Danish, Norwegian and Swedish, are often cited as examples. Conversely, a language defined in this way may include local varieties that are mutually unintelligible, such as the German dialects.
The choice of standard is often determined by a political boundary, which may cut across a dialect continuum.
As a result, speakers on either side of the boundary may use almost identical varieties, but treat them as dependent on different standards, and thus part of different "languages".
The various local dialects then tend to be leveled towards their respective standard varieties, disrupting the previous dialect continuum.
Examples include the boundaries between Dutch and German, between Czech, Slovak and Polish, and between Belarusian and Ukrainian.
The choice may be a matter of national, regional or religious identity, and may be controversial.
Examples of controversies are regions such as the disputed territory of Kashmir, in which local Muslims usually regard their language as Urdu, the national standard of Pakistan, while Hindus regard the same speech as Hindi, an official standard of India. Even so, the Eighth Schedule to the Indian Constitution contains a list of 22 scheduled languages and Urdu is among them.
During the time of the former Socialist Republic of Macedonia, a standard was developed from local varieties of Eastern South Slavic, within a continuum with Torlakian to the north and Bulgarian to the east. The standard was based on varieties that were most different from standard Bulgarian. Now known as Macedonian, it is the national standard of North Macedonia, but viewed by Bulgarians as a dialect of Bulgarian.

Europe

Europe provides several examples of dialect continua, the largest of which involve the Germanic, Romance and Slavic branches of the Indo-European language family, the continent's largest language branches.
The Romance area spanned much of the territory of the Roman Empire but was split into western and eastern portions by the Slav Migrations into the Balkans in the 7th and 8th centuries.
The Slavic area was in turn split by the Hungarian conquest of the Carpathian Basin in the 9th and 10th centuries.

Germanic languages

North Germanic continuum

The Norwegian, Danish and Swedish dialects comprise a classic example of a dialect continuum, encompassing Norway, Denmark, Sweden and coastal parts of Finland. The Continental North Germanic standard languages are close enough and intelligible enough for some speakers to consider them to be dialects of the same language, but the Insular ones are not immediately intelligible to the other North Germanic speakers.

Continental West Germanic continuum

Historically, the Dutch, Frisian, Low Saxon and High German dialects formed a canonical dialect continuum, which has been gradually falling apart since the Late Middle Ages due to the pressures of modern education, standard languages, migration and weakening knowledge of the dialects.
The transition from German dialects to Dutch variants followed two basic routes:

From Central German to Southeastern Dutch in the so-called Rhenish fan, an area corresponding largely to the modern Niederrhein in which gradual but geographically compact changes took place.
From Low Saxon to Northwestern Dutch : This sub-continuum also included West Frisian dialects up until the 17th century, but faced external pressure from Standard Dutch and, after the collapse of the Hanseatic League, from Standard German which greatly influenced the vocabularies of these border dialects.

Although the internal dialect continua of both Dutch and German remain largely intact, the broader continuum that once connected Dutch, Frisian, and German has largely disintegrated. Fragmentary areas of the Dutch-German border in which language change is more gradual than in other sections or a higher degree of mutual intelligibility is present still exist, such as the Aachen-Kerkrade area, but the historical chain in which dialects were only divided by minor isoglosses and negligible differences in vocabulary has seen a rapid and ever-increasing decline since the 1850s.
Standard Dutch was based on the dialects of the principal Brabantic and Hollandic cities. The written form of Standard German originated in the East Central German used at the chancery of the kingdom of Saxony, while the spoken form emerged later, based on North German pronunciations of the written standard. Being based on widely separated dialects, the Dutch and German standards do not show a high degree of mutual intelligibility when spoken and only partially so when written. One study concluded that, when concerning written language, Dutch speakers could translate 50.2% of the provided German words correctly, while the German subjects were able to translate 41.9% of the Dutch equivalents correctly. In terms of orthography, 22% of the vocabulary of Dutch and German is identical or near-identical.

Anglic continuum

The Germanic dialects spoken on the island of Great Britain comprise areal varieties of English in England and of Scots in Scotland and parts of Northern Ireland. Those of large areas north and south of the border are often mutually intelligible. In contrast, the Orcadian dialect of Scots is very different from the dialects of English in southern England—but they are linked by a chain of intermediate varieties.

Romance languages

Western Romance continuum

The western continuum of Romance languages comprises, from West to East: in Portugal, Portuguese; in Spain, Galician, Leonese or Asturian, Castilian or Spanish, Aragonese and Catalan or Valencian; in France, Occitan, Franco-Provençal, standard French and Corsican which is closely related to Italian; in Italy, Ligurian, Piedmontese, Lombard, Emilian, Romagnol, Italian Gallo-Picene, Venetian, Friulian, Ladin; and in Switzerland, Lombard and Romansh.
Focusing instead on the local Romance lects that pre-existed the establishment of national or regional standard languages, all evidence and principles point to Romania continua as having been, and to varying extents in some areas still being, what Charles Hockett called an L-complex, i.e. an unbroken chain of local differentiation such that, in principle and with appropriate caveats, intelligibility attenuates with distance. This is perhaps most evident today in Italy, where, especially in rural and small-town contexts, local Romance is still often employed at home and work, and geolinguistic distinctions are such that while native speakers from any two nearby towns can understand each other with ease, they can also spot from linguistic features that the other is from elsewhere.
In recent centuries, the intermediate dialects between the major Romance languages have been moving toward extinction, as their speakers have switched to varieties closer to the more prestigious national standards. That has been most notable in France, owing to the French government's refusal to recognise minority languages, but it has occurred to some extent in all Western Romance speaking countries. Language change has also threatened the survival of stateless languages with existing literary standards, such as Occitan.
The Romance languages of Italy are a less arguable example of a dialect continuum. For many decades since Italy's unification, the attitude of the French government towards the ethnolinguistic minorities was copied by the Italian government.