Galactic Derelict

Blurb

Galactic Derelict is the second novel in The Time Traders series by Andre Norton. It was first published in 1959, and as of 2012, had been reprinted in eight editions. It is part of Norton's Forerunner universe.
Galactic Derelict continues the series’ premise, an encounter between Western heroes and a mysterious alien race that has used time travel to alter Earth. This novel shifts between present day and the time of Folsom Man, some 10,000 years ago.
Kirkus Reviews comments for this novel “Andre Norton has no peer in his chosen field of science fiction for teenagers…[here] there’s a hint of racial antagonism.”