David Easton is a visionary with his feet firmly planted on the earth. Literally. On a 2-acre site, nestled under steep, wooded hills outside Napa, Calif., Easton is building atwo-story, 2,600-square-foot, French-style farmhouse for himself, his wife, Cynthia Wright, and the two children still living at home. And he's building it out of mud.

"I've been on a mission for 25 years to gain credibility for this material," he says. Easton was studying mechanical engineering at Stanford when he first heard of the work being done in the Rhone Valley, France, on earth-walled construction. In 1975, he built his first earth-walled home in Wilseyville, east of Sacramento. Using a process called rammed-earth construction, he has since built some 300 homes, mainly in California.

Rammed-earth construction has been used in Europe and North Africa for centuries. Two wooden panels are fixed 18 inches apart, providing a mold into which the earthen mixture is poured. This is then dampened and rammed tight. After the mixture has dried, the forms are removed, leaving a rock-hard wall that can last for hundreds of years. Easton has developed a mixture that is 10 percent Portland cement and 90 percent earth (of which 20 percent is clay, 10 percent silt and 70 percent sand and gravel). He also reinforces the walls with half-inch steel rods.

"There is a certain magic to living in buildings with thick earth walls," Easton writes in The Rammed Earth House (Chelsea Green Publishing Co., 1996). There is also something very practical. Earth-walled homes last for hundreds of years, they absorb sound, and remain cool in summer and warm in winter. And since wood is used only in the roof, they are ecologically friendly.

In an attempt to reduce the high cost of constructing the labor-intensive walls, Easton has adapted a technology that has been employed in the building of swimming pools and tunnel casings for more than 50 years. A team of eight workers erects only one plywood panel, then uses high-pressure hoses to blow the earth-cement mixture against it. The process takes a fraction of the time (and cost) needed for rammed-earth construction, and the 18-inch-thick walls are dry enough to support a roof within a day.

This winter, Easton and his wife will take these new methods to Civano, a subdivision of Tucson, Ariz. They are scheduled to build 35 houses in the spring and, if that goes as planned, 2,000 more a few months later.

"This is the culmination of years of work," Easton says. It may also be the beginning of years of work, as this ancient material proves its value to 21st-century builders.