Brick by brick, students learn Petaluma history

Petaluma’s history of adobe construction was alive and well again at Casa Grande High School last Friday, as a local expert on natural clay construction guided students in building bricks like those that have helped the walls of the Old Adobe stand for nearly 200 years.

Stomping into a mixture of Petaluma’s clay-rich soil, students in the earth science course blended material in much the same way that Petaluma Adobe’s builders would have done in the 1830s. Bricks formed in wooden frames hardened slowly in the sun, destined for assembly into outdoor furniture for the campus’ central square.

Leading three classes on the subject in honor of April 22’s Earth Day, Miguel Elliott, a Petaluma native and natural clay sculptor, described the method as a low-cost, low-impact building approach involving a heavy dose of fun.

“Petaluma is a really great place to focus on the natural building movement. Everybody knows what an adobe structure is,” Elliott said. “You could say I’m trying to pick up where General Vallejo left off.”

Citing Petaluma Adobe for sparking his childhood fascination with natural clay construction, Elliott said he began leading workshops on the subject while working for Americorps in Oregon 20 years ago. He spent time in South America, Africa and Asia teaching clay building, with projects that include a South American school and a Chicago nightclub.

His material of choice is actually quite specific, a 70 percent sand, 30 percent clay-and-straw mixture known as “cob” when shaped by hand. Cob could be used for wood-fired ovens, furniture, art and even entire buildings, he said.

“It doesn’t cost much money, because the structures are basically free, right from the earth,” Elliott said.

It was in 1836 that Mexican General Mariano Guadalupe Vallejo first arrived in today’s Petaluma. Using bricks of Petaluma clay, sand, straw and manure, he built the 20,000-square-foot fort many Petalumans now know as Old Adobe. Half of that structure melted in the rain following its abandonment at the turn of the last century, but the remaining portion has stood virtually unchanged for nearly two centuries, said Crystal Battles, ranger at Petaluma Adobe State Historic Park.

The park is a common destination for Petaluma students, where many learn the basics of adobe brick construction.

“These students are learning history, about the earth and how we learn as a community,” said John Shribbs, the Casa Grande science teacher who organized the brick building event.

As leader in an effort to beautify Casa Grande’s central square, Shribbs showed off a concrete pizza oven that was transformed by Elliott’s cob exterior. Students will soon see their bricks incorporated into other elements in the area, which will receive a treatment to ward off rainwater.

“They’re constructing the space they all get to share,” he said.

Students in Shribbs’ advanced placement earth science course were beaming after forming several dozen of the bricks.

“I think people really enjoyed it, especially the stomping,” said Megan Russell, a student in the course.

“I loved it. It opened my eyes to a whole new style of building,” said Monique Els, another student.

Elliott described Petaluma’s clay as ideal for cob and adobe brick-style building, a “turbo clay” that forms easily and dries quickly. He has used it for a number of projects since launching Living Earth Structures upon his 2008 return to Petaluma, though he noted that California does not currently allow the method for anything other than projects on the scale of a small studio.

If permitted on a larger scale, Elliott said California residents would soon come to celebrate the properties of Old Adobe.

“It has natural insulation, which is really wonderful when it’s hot outside,” Battles said.

(Contact Eric Gneckow at eric.gneckow@arguscouri er.com.)