Superstratum

In linguistics, a stratum (Latin for "layer") or strate is a language that influences or is influenced by another through contact. A substratum or substrate is a language that has lower power or prestige than another, while a superstratum or superstrate is the language that has higher power or prestige. Both substratum and superstratum languages influence each other, but in different ways. An adstratum or adstrate is a language that is in contact with another language in a neighbor population without having identifiably higher or lower prestige. The notion of "strata" was first developed by the Italian linguist Graziadio Isaia Ascoli (1829–1907), and became known in the English-speaking world through the work of two different authors in 1932.

Thus, both concepts apply to a situation where an intrusive language establishes itself in the territory of another, typically as the result of migration. Whether the superstratum case (the local language persists and the intrusive language disappears) or the substratum one (the local language disappears and the intrusive language persists) applies will normally only be evident after several generations, during which the intrusive language exists within a diaspora culture. In order for the intrusive language to persist (''substratum'' case), the immigrant population will either need to take the position of a political elite or immigrate in significant numbers relative to the local population (i. e., the intrusion qualifies as an invasion or colonisation; an example would be the Roman Empire giving rise to Romance languages outside Italy, displacing Gaulish and many other Indo-European languages). The ''superstratum'' case refers to elite invading populations that eventually adopt the language of the native lower classes. An example would be the Burgundians and Franks in France, who eventually abandoned their Germanic dialects in favor of other Indo-European languages of the Romance branch, profoundly influencing the local speech in the process.

Substratum

A substratum (plural: substrata) or substrate is a language that an intrusive language influences, which may or may not ultimately change it to become a new language. The term is also used of substrate interference; i.e. the influence the substratum language exerts on the replacing language. According to some classifications, this is one of three main types of linguistic interference: substratum interference differs from both adstratum, which involves no language replacement but rather mutual borrowing between languages of equal "value", and superstratum, which refers to the influence a socially dominating language has on another, receding language that might eventually be relegated to the status of a substratum language.

In a typical case of substrate interference, a Language A occupies a given territory and another Language B arrives in the same territory (brought, for example, with migrations of population). Language B then begins to supplant language A: the speakers of Language A abandon their own language in favor of the other language, generally because they believe that it will help them achieve certain goals within government, the workplace, and in social settings. During the language shift, however, the receding language A still influences language B (for example, through the transfer of loanwords, place names, or grammatical patterns from A to B).

In most cases, the ability to identify substrate influence in a language requires knowledge of the structure of the substrate language. This can be acquired in numerous ways:
* The substrate language, or some later descendant of it, still survives in a part of its former range;
* Written records of the substrate language may exist to various degrees;
* The substrate language itself may be unknown entirely, but it may have surviving close relatives that can be used as a base of comparison.

One of the first-identified cases of substrate influence is an example of a substrate language of the second type: Gaulish, from the ancient Celtic people the Gauls. The Gauls lived in the modern French-speaking territory before the arrival of the Romans, namely the invasion of Julius Caesar's army. Given the cultural, economic and political advantages that came with being a Latin speaker, the Gauls eventually abandoned their language in favor of the language brought to them by the Romans, which evolved in this region until eventually it took the form of the French language that is known today. The Gaulish speech disappeared in the late Roman era, but remnants of its vocabulary survive in some French words (approximately 200) as well as place-names of Gaulish origin. It is also posited that some structural changes in French were shaped at least in part by Gaulish influence including diachronic sound changes and sandhi phenomena due to the retention of Gaulish phonetic patterns after the adoption of Latin, calques such as ''aveugle'' ("blind", literally without eyes, from Latin ''ab oculis'', which was a calque on the Gaulish word with the same semantic construction as modern French) with other Celtic calques possibly including "oui", the word for yes,Matasović, Ranko. 2007. “Insular Celtic as a Language Area”. In Tristam, Hildegard L.C. 2007, ''The Celtic Languages in Contact''. Bonn: Papers from the Workship within the Framework of the XIII International Congress of Celtic Studies. Page 106. while syntactic and morphological effects are also posited.

Other examples of substrate languages are the influence of the now extinct North Germanic Norn language on the Scots dialects of the Shetland and Orkney islands. In the Arab Middle East and North Africa, colloquial Arabic dialects, most especially Levantine, Egyptian, and Maghreb dialects, often exhibit significant substrata from other regional Semitic (especially Aramaic), Iranian, and Berber languages. Yemeni Arabic has Modern South Arabian, Old South