National Park Service officials are preparing to work on removing the black scum coating areas of the Jefferson Memorial in Washington.
National Park Service officials are preparing to work on removing the black scum coating areas of the Jefferson Memorial in Washington. Nikki Kahn Washington Post
National Park Service officials are preparing to work on removing the black scum coating areas of the Jefferson Memorial in Washington. Nikki Kahn Washington Post

The grimy, black biofilm that’s creeping over the Jefferson Memorial

August 12, 2016 10:00 AM