In 1947 a retired Ohio doctor allegedly discovered relics of an ancient civilization, whose men averaged 8 to 9 feet tall in the Colorado desert near the Arizona-Nevada-California line. Howard E. Hill. of Los Angeles disclosed that several well-preserved mummies were taken from caverns in an area roughly 180 miles square, extending through much of southern Nevada
One daughter of Shin-au-av took the chief by the hand and led him to a vast natural gathering area where he saw hoards of happy dead Pauite dancing. The chief said he wanted to see his wife.
The daughter of Shin-au-av agreed with the stipulation that the moment he seized his wife, they must leave the valley without haste and never look back. The Paiute chief promised to obey and when he was reunited with his wife they fled across the valley to return to the living. He forgot his promise to not look back and turned around for one last glimpse of the valley. The instant he did this, his wife vanished into thin air and he found himself alone again - naturally. He returned to his tribe and spent the rest of his earthly life describing the underground realm of Shin-au-av.
The Paiute may have a common lineage with the Hopi further south. The Hopi have legends of an underground world in which they took refuge durring the Great Flood See Hopi Ant People.
In the 1920s Thomas Wilson  an Indian guide claimed that his grandfather had discovered catacombs below the ground in the area. Lost Cities of North & Central America [pg 508]
Wilson's tale was relayed upon hearing a story told by a prospector whose first name has been lost to time. His last name however was 'White'. The miner / prospector claims he fell through the ceiling in a tunnel. Following the tunnel some distance he discovered an underground city. He went on to describe arched stone walls and doorways and a polished round table in a chamber. The chamber contained tall gold spears, although he doesn't elaborate on why he failed to take any of these spears with him. He described designs in the chamber as resembling the work of the Egyptians. At the end of his journey through the underground city he found himself with a view of California`s Imperial Valley. He believed that the tunnel entrance, now located halfway up the side of the mountain had once been a dock and the land below had been underwater at one time. Allegedly, a deal was made with the Smithsonian museum but the evidence was stolen and the entrance concealed he suspects by Smithsonian researchers.
A 1940 mining journal reported worked gold found in a cave near San Bernadino [Kokoweef River of Gold].
Finally In 1947 a retired Ohio doctor stumbled upon the 'lost city' of the Giants in the Colorado Dessert and from there the trail went cold. Oh yes, did I forget to mention that the area of Wingate pass, where the find allegedly occurred is inaccessible in the current era ?
Neanderthal in The Bible
Giants of Lovelock Cave
Lost Races of America
References / Footnote
1. I WILL NEVER SEE WINGATE PASS
2. Bio Thomas Wilson
3. Shin-au-av draws parallels to other World Wide Flood Legends "One day when the sea was angry, Shin-au-av shot it with an arrow and it burst into many small pieces. It then flooded the land until Shin-au-av and his companions almost starved to death." Shin-au-av and The Flood. It also correlates with Hopi Legends that describe a similar apocalyptic scenario and refuge in subterranean abodes.