recorded in the Carrizo Plain area in southeastern San Luis Obispo County. With an estimated magnitude of 7.9, this was the last "Big One" in Southern California. The extreme southernmost portion of the San Andreas fault, which terminates near Bombay Beach at the Salton Sea, last ruptured in 1680. Surface faulting may have extended beyond the boundaries of the regularly acknowledged slip length. Researchers recorded first and second-hand accounts of the ground crack, which was understood to be recent surface faulting and not just the topography of the existing rift. On the extreme northern end of the rupture zone, the surface cracking extended north of Cholame into San Benito County. On the southern end, the population centers were not as close to the fault, and early observers were probably limited to the stretch of the fault between Fort Tejon and Elizabeth Lake, as that was close to the Stockton – Los Angeles Road, the primary inland north−south route then. Evidence of uprooted and displaced trees south of Elizabeth Lake indicates surface faulting along a mole track (an "array of en echelon primary Riedel shears with linking compressional rolls and minor thrusts") that ran directly under three Jeffrey Pines. Two of the three trees examined were tilted in their lower extremity, while the upper portions remained relatively untilted. Tree ring dating confirmed that the trees had originated 10 and 25 years before 1857 and also that the rings began to grow twice as thick on the side in the direction of the tilt. This is a frequently noted compensation of tree tilt. Seismologist Kerry Sieh determined that fault slip and the associated ground disturbance were the source of the mole track and subsequent tree tilt. Foreshocks Various accounts of the event indicate the presence of foreshocks between one and nine hours before the main event, and based on the (uncertain) distribution of those shocks, it is assumed that the beginning of the fault rupture (the epicenter) was in the area between Parkfield and Cholame, about northwest. The lack of standardized timekeeping during this period of California's history contributed to some of the inaccurate reports of when the pre-shocks occurred. Local solar time was being used in 1857 and San Francisco would have been the locality with the most accurate time kept as it was a center of commerce and other activity. Standard time was not followed until the 1880s, with the