Dean M. Chriss
Photography
Mono Lake, Tufa on Blue, California
(Click image to enlarge)
Mono Lake formed at least 760,000 years ago as a terminal lake in a basin with
no outlet. The lack of an outlet causes high levels of salts to accumulate over
time, which makes the water alkaline. The tufa formations seen in this
photograph are made of calcium carbonate. They form when calcium-rich
groundwater enters the alkaline lake water causing calcium carbonate to
precipitate. This slowly forms a calcium carbonate tube or pipe around the
groundwater's entry point. Tufa towers stop growing when their tops become
exposed, either because they reach the lake's surface or because lake level
drops.
In this case the level of Mono Lake began dropping in 1941 when the city of
Los Angeles diverted water from freshwater streams flowing into the lake. As
a result the lake's area was reduced by 31%, alkaline sands and formerly
submerged tufa towers became exposed as the water salinity doubled. Mono
Lake's Negit Island became a peninsula, which made all of the bird nests on it accessible to coyotes and other predators.
This
was catastrophic because 95% of all California Gulls in California (one
fifth of the world's population), in addition to many other migratory birds,
nested on Negit Island. The Mono Lake Committee formed in response and won a legal
battle in 1983 that forced Los Angeles to partially replenish the lake
level. Current drought conditions in the west in addition to increased
evaporation from higher temperatures, both fueled by climate change, make it
nearly impossible to maintain the water levels in Mono Lake today.
This photograph was made possible by a crystal clear blue sky, a fairly wide
angle lens, a polarizing filter, and Kodachrome ISO 25 film. Due to the wide angle of the lens,
polarization increases toward the bottom of the image. That increasingly
eliminates reflections like that of the blue sky from the water's
surface. The corresponding exposure reduction caused by increased
polarization in addition to light attenuation by the water and the film's
low dynamic range renders the lake
bottom nearly black, except for the area just above the leftmost pieces of
tufa. This is better seen in the larger version of the image, available by
clicking on the image above.