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Wash History
2 to 24 Million Years Ago
Geologic record indicates Wash floodplain development
The Las Vegas Wash floodplain was initially formed roughly two to 24 million years ago, as a result of filling of the Las Vegas Valley by sediments that were deposited by erosion of surrounding ranges and higher elevations. The majority of these sediments consist of easily eroded silts and clays with minor amounts of sand and gravel. Geologic evidence indicates that the Wash has undergone at least three natural cycles of down-cutting and subsequent back-filling prior to modern development. The Wash became a tributary to the Colorado River about three million years ago.
For the last few hundred years, the valley has been a source of water in the dry Mojave Desert. Meadows, or wetlands, were supported by a spring complex known as the Big Springs, located in the central part of the valley. Las Vegas Creek was formed by these springs and flowed through the valley, percolating into the ground water system prior to entering the lower portion of the Wash. The lower part of the Wash was ephemeral with the exception of a small spring and wetland area near what is now known as Three Kids Wash.