by Janet Jones | Apr 15, 2017 | Get to Know the Geysers, Geyser Watch
Why is it called Black Pool when it’s blue? One of the most often asked questions at West Thumb Geyser Basin is, “Why is it called Black Pool when it’s blue?” This NPS photo from 1978 shows how it used to look, which is black. The microbes lining the surface of...
