A large valley oak marks the spot where Francisco Lopez reportedly made California's first documented gold discovery in 1842, while working as a rancher on the Rancho San Francisco. The find set off a minor gold rush among Mexican and Californio settlers long before the 1848 discovery at Sutter's Mill that brought the forty-niners, though the remote location kept it from becoming a major mining center.
The tree stands near Placerita Canyon Road, close to the Placerita Canyon Nature Center, making it easy to combine with a visit there. A state historical marker explains the context. The oak itself is an impressive specimen and the canyon setting — live oaks, sage scrub, dry creek bed — gives a good sense of what rural California looked like before the subdivisions arrived.