English-language vowel changes before historic /l/

In the history of English phonology, there have been many diachronic sound changes affecting vowels, especially involving phonemic splits and mergers. A number of these changes are specific to vowels which occur before /l/. Diphthongization occurred since Early Modern English in certain -al- and -ol- sequences before coronal or velar consonants, or at the end of a word or morpheme. In these sequences, /al/ became /awl/ and then /ɑul/, while /ɔl/ became /ɔwl/ and then /ɔul/. Both of these merged with existing diphthongs: /ɑu/ as in law and /ɔu/ as in throw. At the end of a word or morpheme, this produced all, ball, call, fall, gall, hall, mall, small, squall, stall, pall, tall, thrall, wall, control, droll, extol, knoll, poll (meaning a survey of people,) roll, scroll, stroll, swollen, toll, and troll. The word shall did not follow this trend, and remains /ʃæl/ today. Before coronal consonants, this produced Alderney, alter, bald, balderdash, false, falter, halt, malt, palsy, salt, Wald, Walter, bold, cold, fold, gold, hold, molten, mould/mold, old, shoulder (earlier sholder), smolder, told, and wold (in the sense of "tract of land"). As with shall, the word shalt did not follow this trend, and remains /ʃælt/ today. Before /k/, this produced balk, caulk/calk, chalk, Dundalk, falcon, stalk, talk, walk, folk, Polk, and yolk. This L-vocalization established a pattern that would influence the spelling pronunciations of some relatively more recent loanwords like Balt, Malta, waltz, Yalta, and polder. It also influenced English spelling reform efforts, explaining the American English mold and molt vs. the traditional mould and moult. Certain words of more recent origin or coining, however, do not have the change and retain short vowels, including Al, alcohol, bal, Cal, calcium, gal, Hal, mal-, pal, Sal, talc, Val, doll, Moll, and Poll (a nickname for a parrot.) In most circumstances, the changes stopped there. But in -alk and -olk words, the /l/ disappeared entirely in most accents (with the notable exception of Hiberno-English).