These historic ruins are lime kilns used to process local ore from the marble quarries that are now part of UC Santa Cruz campus. Prior to the development of the railroad system through the western United States, quarries of marble in the Santa Cruz area were the only source of lime for cement construction in the Pacific Basin. Lime extracted from the Santa Cruz area was used in the construction of the Panama Canal, the Grand Coulee Dam, and in the reconstruction of San Francisco after the 1906 earthquake. Fuel for processing the lime came from charcoal (at the expense of much forest wood throughout the Santa Cruz Mountains). It was then hauled to ships for transport. Lime mining began in Spanish colonial times. By the early 1930s nearly all mines in the Santa Cruz area closed as less expensive inland sources became available via rail. Marble and granitic aggregate are still actively being mined in the Watsonville and Davenport areas. The marble and granitic rocks are part of the Salinian Basement Complex (Cretaceous and older) exposed through Ben Lomond Mountain.
