Joret line

The Joret line (French ligne Joret) is an isogloss used in the linguistics of the langues d'oïl. Dialects north of the line have preserved Vulgar Latin /k/ and /ɡ/ before /ɡ/; dialects south of the line have palatalized /k/ and /ɡ/ before /ɡ/. This palatalization gave Old French /tʃ/ and /dʒ/, then modern French /ʃ/ and /ʒ/. The line was first identified by Charles Joret and published in 1883.