Faults

Faults Signify Active Tectonics

Faulting is one of the main geologic forces that created Death Valley. Over the last several million years the Earth's crust in the Death Valley region has extended, causing mountains to rise and valleys to sink along faults.

This type of mountain building formed the Basin and Range geologic province, which consists of a series of North-trending valleys (basins) and mountains (ranges) across much of the Great Basin. This crustal extension in Death Valley began in the Miocene (23 to 5.3 million years ago).

 

An illustration of Death Valley's pull-apart basin, with directional arrows showing movement direction along the fault lines.

NPS / Christian Poutre & NPS / J. Jurado

Death Valley’s current fault system is a bit more complicated. A network of two strike-slip fault zones is linked together by a normal fault zone. The normal fault zone is being pulled apart by the lateral (side to side) motion of the two strike-slip faults (see figure).

This type of extensional zone, called a pull-apart basin, was first hypothesized by Burchfiel and Stewart (1966) and is what causes Badwater Basin to sink to the lowest point in North America. The timing of the tectonic shift is somewhat unclear, but Norton (2011) believes the shift occurred around 3 million years ago.

 

Fault scarps in an alluvial fan south of Badwater Basin, with a ledge showing where the basin dropped along the fault line.

NPS photo

Badwater Basin continues to be shaped by these ongoing geologic forces. The alluvial fans along the edge of the basin are terraced by fault scarps from as far back as the Holocene Era (about 11,000 years ago). Roughly every couple thousand years fault movements (large earthquakes) drop the basin even lower. The most recent of these was about 2,000 years ago!

 

A normal fault with a backpack at the base of the fault for scale.

NPS / Christian Poutre

Normal Faults

Other evidence of normal faults can be seen throughout Death Valley such as the roadside exposure along Emigrant Canyon pictured here. As the crust is pulled apart, blocks of crust break and fall against each other. The offset between these blocks are normal faults.

Red lines have been added to the picture to show direction of movement along the normal fault and to highlight a layer that is now displaced by over 20 feet.

 

A strike-slip fault cutting across an alluvial fan below the Panamint Mountains.

Photo by Marli Miller, geologypics.com. Used with permission.

Strike-Slip Faults

Strike-slip faults cause lateral (side to side) displacement, and therefore are easiest to see from above.

Offset stream channels in alluvial fans show the relatively recent strike-slip activity.

 

Chevron folds in Red Wall Canyon.

NPS / Christian Poutre

Thrust Faults

Thrust faults happen when rocks are under compression (pushing together), causing a break that stacks rock layers on top of eachother.

Although currently under extension (moving apart), the rocks that form Death Valley were under compression (pushing together) during Mesozoic time (~252 million years ago to 66 million years ago), which caused thrust faults to stack older rock layers on top of younger ones.

Other evidence of compression includes folds, such as the large fold that sits atop Corkscrew peak and these chevron (neat and angular) folds in Red Wall Canyon.