Sea or clouds?

I marvel at how low clouds can change the appearance of a landscape. From one of valleys bounded by hills to a sea interspersed with islands. I sometimes imagine that I'm seeing how this part of Oregon looked 15,000 years ago. At the end of the last ice age, a constriction in the Columbia River gorge created a 3,000 square-mile lake from the torrent of waters released by a melting glacial dam near Missoula, MT. The turbulent waters of "Lake Allison" would have been about 400 feet deep here.