En réponse à Philippe Caquant :

>This all can very well be understood if we look at a
>geographic map of Norway. Until recently, valleys were
>very isolated from each other, and often the best way
>to get from one region to another was by sea. (Now
>they made tunnels everywhere like worms in a piece of
>cheese, and you have to pay a fee every 15 km).

Actually, geography is not necessary to have a multitude of dialects. You 
don't even need distance! Look at the Netherlands: probably the flatest 
country of the world, and a small one at that, and yet such a multitude of 
dialects that it's common on TV to *subtitle* Dutch people just like people 
speaking a foreign language! And the differences between dialects can be 
lexical, syntactic and morphological (for example my friend's dialect still 
uses "gij" for "jij": "you (sg)" (in other dialects, "gij" is like "thou" 
in English: it's limited to talking to God). It's quite simple: each 
village in the Netherlands has its own distinctive dialect, slightly 
different from its neighbours. Impressive for such a small country! :)

And then if you add the Flemish dialects spoken in Belgium and Fries (which 
is not a dialect but a separate language), you get a beautiful linguistic 
mess :))) .

Christophe Grandsire.

You need a straight mind to invent a twisted conlang.