Natural Bridge Canyon Death Valley National Park CaliforniaLooking into the mouth of Natural Bridge Canyon
After leaving hell, oops I mean Furnace Creek, we attended an afternoon guided Ranger walk to learn more about the geology in Death Valley National Park Natural Bridge Canyon.
Ranger Bob Natural Bridge Canyon Death Valley National Park CaliforniaRanger Bob at mouth of Natural Bridge Canyon
Ranger Bob is a retired geologist working summers at Yellowstone and winters at Death Valley for the last 10 years.  He not only knew his stuff, he got everybody into it.
View west of Death Valley and Panamint Range from Natural Bridge Canyon Death Valley National Park CaliforniaView west of Death Valley and Panamint Range from Natural Bridge Canyon
Although Death Valley itself is young in geologic time, formed a mere three million years ago, some of the rocks that makes up the rugged mountains to the east of the valley date back to around 1.8 billion years old.
Gneiss rock Natural Bridge Canyon Death Valley National Park CaliforniaGneiss old rock
Uplift began about 8-10 million years ago but most of the drastic elevation change occurred in the last 3 million years.
Natural Bridge Canyon Death Valley National Park CaliforniaNatural Bridge Canyon
Four mountain ranges to the west of the valley create such a strong rain shadow that the average precipitation is less than two inches a year.  Death Valley is considered the driest place in North America.  Yet during unusually heavy storms, rain washes rocks, sand and gravel off mountainsides and down into canyons.
Alluvial fans Death Valley National Park CaliforniaMultiple alluvial fans
Where a canyon opens onto the valley floor the water spreads out, losing velocity and depositing the water-carried material at the canyon mouth, or beyond, creating an alluvial fan.  As the mountains lift the valley sinks.  Yet erosion can’t keep up as the valley sinks faster than it fills.  Even after millions of floods, nearly 9000 feet (2750 meters) of sand, silt, gravel and salt fill the valley basin.
Natural Bridge Canyon Death Valley National Park CaliforniaWater erosion on canyon wall
Because this erosion process has been going on for millions of years some rock layers are concentrations of rock, sand and gravel compressed by more layers into an interesting conglomerate like was seen in Mosaic Canyon.
Natural Bridge Canyon Death Valley National Park CaliforniaRanger Bob at Natural Bridge
And then there are numerous faults as this land known as the “Basin and Range” spreads apart fracturing along parallel fault lines creating the Panamint Mountains to the west and the Black Mountains to the east with Badwater Basin in between.  A large earthquake could cause the valley in between to drop a few more feet below sea level.