The Shenandoah and Potomac Rivers, meeting up and passing through the Potomac Water Gap in the Blue Ridge Mountains, as seen by the the Operational Land Imager (OLI) on Landsat 8 on April 20, 2016, from an altitude of about 700 kilometers (430 miles). Harpers Ferry, West Virginia, is between the two rivers as they squeeze through the gap. The warmer valleys have already turned green with the spring, but the colder ridge tops are still brown.