Orientale Basin (IMAGE) Brown University Caption The impact that formed the Moon's Orientale basin created a sea of melted rock 220 miles across and 6 miles deep. Similar melt seas probably existed in at least 30 other large impact basins. Rocks formed as these seas cooled and solidified could be mistaken for rocks formed very early in the Moon's history, according to researchers at Brown University. Credit NASA Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.