California Code, Government Code - GOV § 425.9

(a) The Legislature finds and declares that San Joaquin Soil is the official soil of California. It is one of four soils to be originally described at the beginning of this century, and the beginning of soil studies in California. San Joaquin Soil is approximately 50,000 to 250,000 years old and was derived from and deposited by the runoff of swollen streams during the glacial period, from mountain glaciers in the Sierra Nevada.

(b) The Legislature hereby designates San Joaquin Soil as the official State Soil.