Riders of the Three-Toed Horse

The following review is from Lois Tilton in the Internet Review of Science Fiction:

Everyone knows that when doors and roads suddenly appear where there were no such doors and roads a moment ago, they usually lead to trouble. But geologist Elias Ullstrom has been offered a new job in Agate County, somewhere in the scablands of Eastern Washington, so that is the road he takes. His job is a mineral survey of the canyons belonging to the Awattamapum tribe, but the local game warden has a warnin...