many thanks for this thread..
its a real help for me..
i can recognise the different types of harmony
when i hear them..
but due to absence of any formal musical education,
dont have the theoretical/technical toolbox
to understand how they're constructed and applied..

something i realy enjoy in american folk,
as opposed to my 'isolationist' small island english indiginous music,
is the additional influence of 19th century east european and jewish migrant traditional music,
adding extra mournfullness and soul to the plaitive droning
harmonic structure that i love about the minor chord
songs fron UK that were arriving in america at the same period
in history..
maybe often on the same ships,
..different european cultures hearing each others songs on the long
fearful voyage across the atlantic..