for between the land of aman that in the north curved eastward , and the east-shores of endor ( which is middle-earth ) that bore westward , there was a narrow strait , through which the chill waters of the encircling sea and the waves of belegaer flowed together , and there were vast fogs and mists of deathly cold , and the sea-streams were filled with clashing hills of ice and the grinding of ice deep-sunken .