PROC. CAL. AGAD. SCI., 4th Series, Vol. XI 



[DICKERSON] Plate 29 



Fig. 1. View looking southeast along the Hayward fault line from highest point in 

 road about one and one-half miles northwest of Petaluma reservoir. Fault sag pond in the 

 middle ground. Petaluma reservoir in distance. 



Fig. 2. Flanks of Sonoma Mountain. Plateau determined by hard, resistant tuff-brec- 

 cia and lava flows overlain by softer shales and sand-stones of the Neohipparion beds of 

 Lawler Ranch, a quarter of a mile away. 



