The project is a 2,600 square foot house for an amateur naturalist, located in the foothills of the Tucson Mountains. The design was inspired by the form and geology of the site. The dominant topographical features of the site are two hills of exposed rhyolite: a grey-violet volcanic tuff. The hills were formed by successive outpourings of viscous volcanic ash that flowed laterally over the land and compressed as they cooled giving the rock a pronounced horizontal grain. The house is sited at the saddle between the two hills. Sections reveal the paradoxical form of the saddle. In one direction the ground is convex in form with the house at the top; in the other direction it is concave with the house at the bottom. The orthogonal forms of the house are a neutral register that reveals the complex, curved form of the saddle. The foundation is cut into the bedrock, so that the house does not dominate the hillside. The house can only be glimpsed obliquely from the street, being screened completely by the low, south hill when one is directly in front of the house.

The plan is organized by five parallel masonry masses that extend from the north hill. These masses contain the service elements of the house. The living spaces of the house occur between these masses and are enclosed by glass. The house is cut into the ground so that from some angles it disappears completely. The butterfly roof repeats the natural drainage pattern of the site, returning the water to the washes that extend down the hill on the east and west sides of the house.