How do different dialects form? I hate to repeat myself.
In the UK quite the reverse is happening so it might give some clues how it started.
Accents can vary noticeably in a matter of a few miles but I have heard many times that they are not as distinct as they once were.
Some accents have their own vocabulary and these words can be traced back to origins outside the UK.
The most obvious would be from the North-East where words such as ducalpro - dju-kal, parnepro - pa-ni are virtually incomprehensible to the rest of the UK but would be understood in Scandinavian nations.
The merging of our national accents has been put fairly and squarely on exposure to broadcast media and increased mobility.
Even as recently as the 1930’s people from one end of the country had little idea how others spoke.
The UK has had many waves of invasion from the Saxons, Angles, Normans and these all brought their own tongue with them.Some, such as the Vikings, settled in certain areas and so the remains of their language is still there in the local vernacular.
We have had fairly recently waves of immigration to the UK from former Commonwealth countries who brought their own languages with them and their own way of speaking English.
Again they have settled in certain areas so that there is now a distinct accent in Leicester as spoken by the largely Indian minority or in Bradford where there are many Pakistani and Bangladeshi immigrants.
I have noticed that this has affected the indiginous population to a small degree through my work with convicts.
Immigrants tend to inhabit the poorer regions of our cities and so do many offenders, they mix in the same schools and grow up in the same neighborhoods, little surprise then that there is some cross-cultural influence.
Possibly this could be described as an accent in the process of being formed.
casdave has answered the OP pretty effectively. You can still see the process at work in Wales, where the Welsh accent reflects the sounds and speech patterns of the Welsh language, even among non-Welsh speakers.
Largely because London and South Eastern accents are grossly over-represented in the British media. If the BBC presented us with a mix of accents which actually reflected the way in which people in England speak, it wouldn’t be such a destructive influence. One particularly outstanding feature is the South London glottal stop, which seems to have crept into the speech of younger people throughout the country (think of Eliza Doolittle saying “The water in Majorca …”).
Actually, “water” is a good example of what casdave is talking about. People of my grandparents’ generation (born just before WWI) in Sheffield pronounced “water” with a short “a” (to rhyme with “fatter”). People under the age of 25 in Sheffield invariably pronounce it as “war’ uh”, with a glottal stop.
It’s also evident that American pronunciations and usages are becoming more commonplace in British English (e.g. “SKED-ule” for “schedule” is pretty standard now), as are some Australian habits of speech, especially the use of a rising intonation at the end of a declaratory sentence?
oh, and here i was thinking it was due to the size of one’s mouth… but think about it, say scottish in a scottish accent and you scrunch your mouth tight (get the connection), say london in a london accent and you open your mouth wide and loud…!
but what your saying is that i’ve been subjected to far too much daytime australian soap? this is why i’m ending all sentences with ‘but…’ these days! great gallah’s!
I’ve seen it (start to) happen. If you have a fairly isolated group of people – in this case, sixty American students in an area where we were literally the only Anglophones – it takes surprisingly little time. Within four months, we’d developed a blend of English, Spanish, and Catalan that was almost incomprehensible to outsiders. Spanish sounds tended to become Anglicized, which wasn’t too surprising, but eventually the process started to reverse itself and we found ourselves speaking English with a slight Spanish accent. I suspect that if we’d stayed another year, the language we were speaking would have evolved into a genuine, distinct dialect. (The process was probably hastened by the fact that we wanted to differentiate ourselves from other Americans. I’ve since noticed that people who speak with distinct regional accents also tend to have a strong sense of regional pride. Make of that what you will.)
TomH – That’s an Australian habit of speech? I always thought it was, like, a Valley girl one?