Lime Kiln

Lime kilns are an ancient technology that was standard in America until the early 1900s. This particular kiln is a stone chamber lined with firebrick and dug into a hillside (click the photo for full size). A charge of limestone boulders was stacked in the kiln, leaving arched bays behind these two openings that were filled with wood. The stone would be burned for several days until it was fully calcined into lime, calcium oxide. This site, in the Santa Cruz Mountains of coastal California, was suitable for lime-making because it had good rock and a large supply of redwood for fuel. See more about making lime cement here.