Geology > Death Valley Geology
Badwater
The Birth of Death Valley
Shake Down
This geographic region--known as "Basin and Range"-- is spreading apart,
fracturing the earth's crust along parallel faultlines. Huge
blocks of land between the faults tilt like seesaws as the
extention continues. You are standing above the dropping edge
of a
fault
block that is rising on its other side to
create the Panamint Mountains. Behind you, the steep face of
of the Black Mountains is another rising fault block edge. These
forces are still active. The next large earthquake could
cause Badwater Basin to drop a few more feet below sea level.
The Black Mountains
The oldest rocks - Relics of the Precambrian world in Death Valley The steep face of the Black Mountains is
made up of some of the oldest rocks in Death Valley. These 1.7 billion-year-old
Precambrian
rocks are the
remnants of an ancient volcanic mountain belt with flanking deposits of mud and sand. About 1.8-1.7 billion
years ago, these
volcanic
and
sedimentary
rocks were severely metamorphosed—altered, recrystallized, and
partially remelted by the Earth's internal heat and by the load of overlying younger rocks. The original rocks
were transformed to contorted
gneiss,
making their original parentage almost unrecognizable.
1.7 billion-year-old
metamorphic
rocks. Quartz-feldspar gneiss dominates the mountain face above Badwater.
11 million years ago, these venerable rocks were injected with magma that solidified to form the Willow Spring
pluton.
The diorite to gabbro composition of the Willow Spring pluton blends well with the dark Precambrian
gneiss, so you'll have to look carefully to see the contact between the two rock types.
Salty Remnants
Beneath the dark shadows of the Black Mountains, a great, extraordinarily flat expanse of shimmering white
spreads out before you. You are at Badwater, at -282 feet it is the lowest spot in the Western Hemisphere. Step
onto the trail and you'll see that the white expanse is made up of billions of crystals of almost pure table
salt! As your feet crunch along the trail that leads onto the valley floor, you are walking on the salty
remnants of a much greener, lusher time in Death Valley's relatively recent past.
Not long ago, during the Holocene (about 2000-4000 years ago), the climate was quite a bit wetter than today. So
wet that streams running from nearby mountains gradually filled Death Valley to a depth of almost 30 feet. Some
of the minerals left behind by earlier Death Valley lakes dissolved in the shallow water, creating a briny solution.
The Desert Returns
The wet times didn't last. The climate warmed and rainfall declined. The lake began to dry up. Minerals dissolved
in the lake became increasingly concentrated as water evaporated. Eventually, only a briny soup remained, forming
salty pools on the lowest parts of Death Valley's floor. Salts (95% table salt - NaCl) began to crystallize,
coating the surface with a thick crust about three to five feet thick.
Here at Badwater, significant rainstorms flood the valley bottom periodically, covering the salt pan with a
thin sheet of standing water. Each newly-formed lake doesn't last long though, because the 1.9 inch average
rainfall is overwhelmed by a 150-inch annual evaporation rate. This, the nation's greatest evaporation
potential, means that even a 12-foot-deep, 30 miles long lake would dry up in a single year! While flooded, some
of the salt is dissolved, then is redeposited as clean, sparkling crystals when the water evaporates.
Filling in the Gaps
Even as the basins and ranges form,
erosion
wears down the
mountains. Debris from the surrounding area washes into this basin
since it has no outlet to the sea. But erosion cannot keep
up with the
geologic
forces that continue to create Death Valley--
the basin drops faster than it fills. After millions of floods, nearly 9,000 feet
of sand, silt, gravel and salt fill the valley basin.
At the top of the
alluvial fan
to the south, a series of gravel
banks run parallel to the mountain face. The fault block,
dropping during a massive earthquake, caused these fault
scarps. At
about 2,000 years old the scarps are recent evidence of the
forces that have created, and continue to shape Death Valley.
Rock Bottom
As the lowest point in the Western Hemisphere, Death Valley
belongs to a world-wide geographic rogues' gallery, whose
members share these defining features:
Crystal Power
The vast, surreal salt flats of Badwater Basin change constantly. Salt
crystals expand, pushing the crust of salt into rough, chaotic
forms. Newly formed crystals ooze between mudcracks, sketching
strange patterns on the surface of the salt flat. Passing
rainstorms wash off windblown dust and generate a fresh layer
of blinding white salt. Floods create temporary lakes that
dissolve salts back into solution, starting the process all over again.
Intense Concentration
The source of Badwater's salts is Death Valley's drainage system of
over 9,000 square miles--an area larger than New Hampshire. Rain
fallling on distant peaks creates floods that rush ever lower. Along
the way, minerals dissolve from rocks and join the flood. Here,
at the lowest elevation, floods come to rest, forming temporary lakes. As
the water evaporates, minerals concentrate until only the
salts remain. After thousands of years, enough salts have washed
in to produce layer upon layer of salt crust.
Sodium Chloride--better known as table salt--makes up the majority of
salts on Badwater Basin. Other evaporative minerals found here include
calcite, gypsum, and
borax.
Bad Water
Water is rare and precious in Death Valley. A surveyor could not get his mule to
drink from the pool. He wrote on his map that the location had "bad water," and the name stuck.
Badwater Pool is not poisonous just salty, as the presence of
pickleweed, aquatic insects, and larvae proves. It is also home to one of
Death Valley's rarest animals-- the Badwater Snail. These tiny mollusks
exist only in a few springs at the edge of Death Valley salt flats.
Ancient Aquifer
Ancient water fills this pool year-round. Much of it began as
Ice Age snow and rain hundreds of miles away in the mountains
of central Nevada. The run-off seeped into porous limestone
bedrock and began a long underground flow through a regional
aquifer.
It emerges here at Badwater along the faultline at the mountain's
base. Salts dissolve from old deposits and flow to the surface,
making the spring water "bad."
Desert Habitats
Landforms and Erosional Processes
Death Valley Geology
The steep face of the Black Mountains rises from the valley floor. Few visitors realize that these mountains are made up of some of Death Valley's oldest rocks.
Looking toward the Panamint Mountains across the Badwater basin, flooded after an unusually heavy rain
At about 2,000 years old the scarps are recent evidence of the forces that have created, and continue to shape Death Valley.
Salts dissolve from old deposits and flow to the surface, making the spring water "bad."
After millions of floods, nearly 9,000 feet of sand, silt, gravel and salt fill the valley basin.
Ancient water fills this pool year-round. Much of it began as Ice Age snow and rain hundreds of miles away in the mountains of central Nevada.
Death Valley was not created by a river's erosion. Movements in the earth's crust have dropped it to such great depths.
The Badwater salt plain as seen from Dante's View.
The water evaporates until only the mineral salts remain.