Vol. XI] DICKERSON—PT. REYES AND SANTA ROSA QUADRANGLES %\ 



shales contain essentially the same fauna as that of the type 

 locality of the Millerton formation. Tom's Point, as will be 

 seen from a study of Figure 1, Plate XXXII, and Figures 1 

 and 2, Plate XXXIV, has been much disturbed by faulting 

 along the San Andreas Rift. Typical fault-sag ponds occur on 

 the top of Tom's! Point along two marked lines of faulting. 

 The fault-sag pond shown in Figure 1, Plate XXXII, is on the 

 western end of the point. Another fault-sag pond occurs about 

 a hundred yards east of this locality, marking a fault which is 

 apparent in the picture of the cliff-section shown in Figure 1, 

 Plate XXXIV. The two pictures shown in Plate XXXIV indi- 

 cate considerable disturbance of the Millerton formation, as 

 dips as high as 20° to 25° are common at this point. The 

 best stratigraphic section of the Millerton formation was 

 found in the headland a mile and a half northwest of Miller- 

 ton Station, on the northwest side of this point. Enough 

 fossils were obtained from these beds to prove that the fauna 

 was the same as that of the Millerton at its type locality. 

 In the west end of the cliff-section, 50 feet of conglomerate 

 is exposed and it exhibits a pronounced dip of 23° E. with 

 strike of N. 20° W. This strike and dip is quite uniform for 

 several hundred feet until a point is reached about sixty feet 

 west of the railroad, where one of the faults of the San 

 Andreas Rift Zone has shattered the section. The conglom- 

 erate strata at the west end of the point are 65 feet in thick- 

 ness and are overlain by 85 feet of carbonaceous tan-colored 

 sandstone and dark gray shale containing marine shells in its 

 middle portion. A prominent conglomerate member two feet 

 in thickness is next observed. The latter deposit is overlain 

 by more carbonaceous tan-colored sandstone and dark gray 

 shale, 23 feet in thickness. A fault apparently intervenes 

 at this point and the underlying strata are not exposed east 

 of it. Near the railroad an erosional unconformity appears 

 to be present between the Millerton formation of Lower or 

 Middle Pleistocene age and the Tomales formation of Upper 

 Pleistocene age. The Tomales formation at this point is com- 

 posed of a tan-colored sandstone and conglomerates — per- 

 haps fanglomerates would be a better designation — lighter 

 in color than the tan-colored sandstones of the Millerton for- 

 mation. The outcrops of the Tomales formation in this vi- 



