If we look on icelandic only, they are consistent by using /o/ and /e/ in the earliest writings, later we see both /o/, /u/ and /e/, /i/, and even later again only /u/ and /i/ (of course we do have /a/ all the time). And we see that /o/ like sounds can change to /u/ in unstressed position, like in "kölluðu" where the second /u/ used to be an /a/, and then a /ö/.

This just look like a classic sound change, the problem start when we look on the other nordic languages, they tell os nothing, because either they use both /u/ and /o/ and /e/ and /i/ (sometimes æ), so the question remains open.


And yeah, thanks for the reply :)

--- In norse_course@yahoogroups.com, "Brian M. Scott" <bm.brian@...> wrote:
>
> At 2:39:52 PM on Saturday, December 3, 2011, Hrafn wrote:
>
> > My teacher argue that the vowel triangle for vowels in
> > final syllable was /e/, /o/, /a/ before 1200. He say the
> > oldest text are pretty consequent about using e and o,
> > where later icelandic use i, u.
>
> This is true: they are. (By the way, Dan. <konsekvent> =
> Eng. <consistent>, not <consequent>.) However, it's not
> clear whether this is an indication of pronunciation or just
> a scribal convention. Here, in my translation from the
> German, is what Gutenbrunner says in his Historische Laut-
> und Formenlehre des Altisländischen:
>
> Since the original sound was /i, u/, cf. spellings like
> <foþur> (208), <fotum> (215), <oþali sinu> (219) on
> inscriptions with o-rune, and the Modern Icelandic
> dialects show no trace of a time with /e, o/, there is a
> question whether writing <e>, <o> was a purely
> orthographic rule of the written language, or whether /e,
> o/ were pronounced in the 12th century. It is in any case
> striking that the pronunciation /e, o/ disappeared so
> quickly and so completely, and this speaks in favor of a
> feature of the written language. On the other hand, the
> 'hiatus' in the u[m]l[aut] tendency §36f. could be
> considered an indication that already at some earlier time
> in the development of the Nordic languages unstressed /i/
> had for a relatively short time so open a pronunciation
> that it did not cause u[m]l[aut].
>
> I've managed to track down the runic citations in Rundata:
>
> (208) is Br Sh3:
>
> §A ...þi---- (+) -ftir + foþur (:) sin (:) þurbio-...
> §B f
>
> §A ... [e]ptir fǫður sinn Þorbjǫ[rn].
> §B ...
>
> §A ... in memory of his father Þorbjǫrn.
> §B ...
>
> (215) is N 540:
>
> §A furu- trikia frislats a
> §B uit auk uiks fotum uir skiftum
>
> §A Fóru[m] drengja Fríslands á
> §B vit, ok vígs fǫtum vér skiptum.
>
> §A We travelled to meet the valiant men of Frisia
> §B (and) we divided the spoils of the fight.
>
> (219) is N 210:
>
> aRintr × karþi × kirkiu × þesa × kosunr × olafs × hins ×
> hala × a oþali × sinu
>
> Eyvindr gerði kirkju þessa, goðsonr Ã"lafs hins
> Hála/Halla/Helga, á óðali sínu.
>
> Eyvindr, godson of Ã"lafr the Slippery/Crooked/Holy made
> this church on his allodial land.
>
> > He say, that in 600 - 700 while the i-mutation still was
> > productive, old /e/, and old /i/ was still separated. But
> > after the i-mutation became unproductive, they merged into
> > /e/, and old /u/ and /o/ merged into /o/. And then first
> > later, they was raisen to /u/ and /i/.
>
> > That do explain why we have words with /i/ without
> > i-mutation: hundi, landi, faðir
>
> It's not needed in order to explain any of these. Both
> <hundr> and <land> are a-stem nouns, in which the dative had
> the ending *-ai in Proto-Germanic. This became *-Ä" in
> Proto-Scandinavian, which was then shortened to *-e and
> never triggered i-umlaut.
>
> <Faðir> has a different story. Pre-Germanic had *faþÄ"r,
> still with stress on the second syllable. By Verner's Law
> this became Proto-Germanic *fáðÄ"r. The *Ä" seems to have
> been very open, perhaps better represented as *Ç£, since it
> subsequently became *ā in Proto-Northwest-Gmc. (Cf. runic
> <swestar> 'sister' in the inscription N KJ76 U, dated to ca.
> 400 CE.) In Proto-Scand. it was shortened (e.g., *faþar
> 'father') and then raised, first to /e/ and later to /i/,
> apparently not early enough to trigger i-umlaut.
>
> It's also worth bearing in mind that umlaut was sometimes
> reversed by analogy with non-umlauted forms in the same
> paradigm.
>
> I'm not saying that he's necessarily wrong, but the matter
> isn't really very clearcut, and the evidence admits more
> than one interpretation.
>
> Brian
>