The upper Kern River Canyon was created primarily as a result of tectonic forces, and not just by the erosional force of the river.
 The geologically active Kern Canyon Fault runs the length of the canyon, from the river's headwaters down to the Walker Basin about 10 miles (16 km) south of Lake Isabella.
The river's course has been modified several times throughout ancient geological history.
Prior to 10 million years ago, the Kern River flowed into the San Joaquin Valley at a point further south, along what is now Walker Basin Creek, which outlets north of Arvin.
Uplift west of the Kern Canyon Fault blocked the river and forced it to cut a new course further north, forming the steep gorge below Lake Isabella and Bakersfield.
The upper part of the Kern River canyon, at least above Golden Trout Creek, was widened and deepened by glaciers during the Ice Ages.
The Kern Canyon fault passes very close to Isabella Dam, and is considered a threat to the dam's structural stability.

The Kern River Oil Field is adjacent to the river on the north, just before the river flows into Bakersfield.
 The large oil field, on low hills which rise gradually into the Sierra foothills, formerly allowed much of its wastewater to drain directly south into the river.
However, modern environmental regulation ended this practice, and the contaminated water is now cleaned at water treatment plants and used to irrigate farms in the valley to the west.
The upper Kern River Canyon was created primarily as a result of tectonic forces, and not just by the erosional force of the river.  The geologically active Kern Canyon Fault runs the length of the canyon, from the river's headwaters down to the Walker Basin about 10 miles (16 km) south of Lake Isabella. The river's course has been modified several times throughout ancient geological history. Prior to 10 million years ago, the Kern River flowed into the San Joaquin Valley at a point further south, along what is now Walker Basin Creek, which outlets north of Arvin. Uplift west of the Kern Canyon Fault blocked the river and forced it to cut a new course further north, forming the steep gorge below Lake Isabella and Bakersfield. The upper part of the Kern River canyon, at least above Golden Trout Creek, was widened and deepened by glaciers during the Ice Ages. The Kern Canyon fault passes very close to Isabella Dam, and is considered a threat to the dam's structural stability.
The Kern River Oil Field is adjacent to the river on the north, just before the river flows into Bakersfield.  The large oil field, on low hills which rise gradually into the Sierra foothills, formerly allowed much of its wastewater to drain directly south into the river. However, modern environmental regulation ended this practice, and the contaminated water is now cleaned at water treatment plants and used to irrigate farms in the valley to the west.
Kern River