Mojave River

The Mojave River could be called an "Upside-down and Backwards" river. "Upside-down", because the water flows below ground, under the sand. "Backwards", because instead of flowing toward the ocean as rivers do, the Mojave flows inland, terminating in the middle of the desert.

The ephemeral waters of the Mojave originate in the watershed of the San Bernardino Mountains. Water gathers from north of the ridgeline and flow down a series of creeks and washes, either underground, or combine in either Deep Creek or Miller Creek, the main above ground sources of the Mojave River before it slips beneath the surface.

The Mojave waters do come above ground. Usually, the river flow can be seen at the upper narrows between Victorville and Apple Valley, then downstream past Barstow at the lower narrows as the river begins its way through Afton Canyon. The river winds down the canyon and seeps into the sand disappearing before it reaches Soda Lake near Baker.

The Mojave Road followed along the river from Soda dry lake to the Cajon Pass. Desert Indians used this as a trade route where water could easily be found on the way to and from the coast. Later, the Old Spanish Trail and Salt Lake Trail (Mormon Road/Trail) joined up with the river near where Daggett is today.

Map of the Mojave River

The Mojave River and Associated Lakes
 

The Mojave River is the largest drainage system in the Mojave Desert. It's modern extent and capacity is only a fraction compared to its extent during the Last Glacial Maximum. At its peak during this last ice age, the Mojave River drainage basin extended from the San Bernardino Mountains in the west; it flowed east and north ultimately merging with the Amargosa River before draining into Lake Manley in Death Valley. At this peak period, waters of the Mojave River drainage system flowed through, or contributed water to, several great Pleistocene Lakes: Lake Manix (which incorporated modern dry lake basins Afton, Troy, Coyote, Harper, and Cronese basins), and Lake Mojave (including dry Soda Lake and dry Silver Lake basins)(see the map on the Changing Climates & Ancient Lakes page). Today Soda Lake is the current terminal point of the Mojave River (although it has flowed into Silver Lake in historic times).

This drainage system evolved along with the changing landscape beginning in late Tertiary time when concurrent tectonic uplift of mountain ranges around the Mojave region and changes in regional climatic conditions were occurring. The modern river system began developing as westward-flowing stream drainages were blocked by the uplift of the Transverse Ranges along the greater San Andreas Fault System. The combination of blocked drainage systems and increased precipitation with the onset of cooler or ice age conditions at the close of the Tertiary resulted in the filling of basins with water (and sediments). Progressively through the latest Tertiary and into the Quaternary periods, lakes filled and stream overflowed through low divides between ranges and flooded adjacent basins. In this manner, the Mojave River evolved from the spilling over of lakes in the western Mojave Desert region. These large lakes do not exist today. Two large lakes that played perhaps a most significant role in the development of the landscape in the Mojave National Preserve area were Lake Manix and Lake Mojave. Sediments associated with these ancient lake deposits (and others in the region) record a story of climate change in the region.

Lake Manix was a large inland lake that was located in the Barstow, CA region (dry Troy Lake and Coyote Lake are remnants of this larger lake basin), and Mojave Lake in the Baker, CA region (dry Silver Lake and Soda Lake are remnants of this ancient lake basin). The development of these lakes and other lakes in the region was progressive with time, with Manix Lake filling first, and Mojave Lake forming later when the Lake Manix filled to capacity and spilled westward, ultimately carving Afton Canyon during the last glacial maximum about 18,000 years ago.

Layers of alluvium exposed in Afton Canyon reveal that changes in the landscape have occurred over time. The different colored layers of sediments exposed in the cliffs reflect changing environmental conditions and stream source areas as sediments filled a basin. Afton Canyon formed when a great Pleistocene-age lake that filled the Manix Lake Basin overflowed through a low divide, creating a new path for the Mojave River. Through portions of Afton Canyon the Mojave River is a perennial stream fed in dry periods by groundwater. In the image above the Mojave River is hidden in the thick tamarisk (salt cedar) and other brush in the foreground. The intermittent stream draining a small side canyon produced the fan-like sediment apron where it enters the Mojave River floodplain. Note the elevated stream terrace on both sides of the side canyon.