but it is said among the elves that it lay far off in the east of middle-earth , and northward , and it was a bay in the inland sea of helcar ; and that sea stood where aforetime the roots of the mountain of illuin had been before melkor overthrew it many waters flowed down thither from heights in the east , and the first sound that was heard by the elves was the sound of water flowing , and the sound of water falling over stone .