This house might seem precariously situated, straddling two sides of a wash, on the edge of a cliff, but the outcropping is stable, made of tough, slow-cooled volcanic basalt. The name “rimrock” refers to this type of situation, with a sheer rock wall at the upper edge of a plateau or canyon. The seam below the house is a natural, preexisting path for animals, who use it to get from the plateau to the river.