Sand
tufa formation at Mono Lake.
Tufas
are limestone structures that are the result of a chemical reaction
between carbonate rich Mono lake water and calcium rich spring
water. Since it needs both spring and lake water for the reaction
to take place, tufa formation only takes place below the surface
level of the lake.
Sand
Tufas are a special kind of tufa that are formed below the surface
of the sand where springs bubble up at the lake edge.
The
sand surrounding the spring's path is saturated with lake water.
The chemical reaction that takes place in the wet sand around
the edge of the spring forms hard tubes of sand grains cemented
by limestone.
These tubes form completely under the surface of the sand and
are not visible.
Beginning
in 1941, water that would normally flow into Mono Lake was diverted
to supply water for the increasing needs of the Los Angles area.
This caused the water level in Mono Lake to drop dramatically.
As
the water level was dropping, the lake's wave action washed
away loose sand from around the hard spring tubes or "sand
tufas" exposing them.
As
the lake level continued to drop formations of sand Tufas were
left behind on what has become dry land.
Mono
Lake, California