from ered luin flowed the six tributaries of gelion : ascar ( that was after named rathloriel ) , thalos , legolin , brilthor , duilwen , and adurant , swift and turbulent streams , falling steeply from the mountains ; and between ascar in the north and adurant in the south , and between gelion and ered luin , lay the far green country of ossiriand , the land of seven rivers .