Radak: They used to worship, on tall mountains and hills, gods that they would put there, "v'Sachas Kol Etz Ra'anan" (Devarim 12:2) in streams and canyons. He should prophesize as if he speaks to them. The Bamos, Mizbechos and sun-images built on them will perish and be broken. It mentions the worshippers amidst the worshipped due to the deed that was done with them ? "Bamoseichem; ? Mizbechoseichem? Chamaneichem? Chalaleichem; ? Giluleihem" (3-5).