Lake Mead near Hoover Dam

Vertical

View of Lake Mead in the vicinity of Hoover Dam (mostly hidden, far left): A fall in water level is revealed by the white “bathtub ring,” where the surface layers of previously inundated sandstone have been altered by the action of cyanobacteria, or blue-green algae.

NPS Photo by Susann a Pershern, Submerged Resources Center

Horizontal

View of Lake Mead in the vicinity of Hoover Dam (mostly hidden, far left): A fall in water level is revealed by the white “bathtub ring,” where the surface layers of previously inundated sandstone have been altered by the action of cyanobacteria, or blue-green algae.

NPS Photo by Susann a Pershern, Submerged Resources Center

Thumb

View of Lake Mead in the vicinity of Hoover Dam (mostly hidden, far left): A fall in water level is revealed by the white “bathtub ring,” where the surface layers of previously inundated sandstone have been altered by the action of cyanobacteria, or blue-green algae.

NPS Photo by Susann a Pershern, Submerged Resources Center
view counter
view counter

Recent Stories

Algae, plants and humans: three groups of organisms that used chemistry to change the planet.

Peaks protected fifty years ago by the Wilderness Act no longer keep mountain goats safe from human impact.

By the 1920s, California had lost all of its grizzly bears—once considered a distinct species and an emblem of the state.

Preconceptions skew our view of the biggest killer in the developed world, atherosclerosis.