upon ... mountains - High places were selected by idolaters on which to sacrifice, because of their greater nearness to the heavenly hosts which they worshipped (Deu 12:2).
elms - rather, “terebinths” [Maurer].
shadow ... good - screening the lascivious worshippers from the heat of the sun.
daughters ... commit whoredom ... spouses ... adultery - in the polluted worship of Astarte, the Phoenician goddess of love.