Where does “Alta” come from?

Alta (Norwegian Bokmål) comes from Finnish ala-, from Proto-Finnic ala, from Proto-Uralic ëla — below.

Ancestry of “Alta”, step by step

StepLanguageWordMeaning
1Finnishala-under-, sub-, lower, nether; inferior
2Proto-Finnicalalower; under
3Proto-Uralicëlabelow
Every word from Proto-Uralic ëla →Every word from Finnish ala- →Every word from Proto-Finnic ala →