104 



University of California Publications. 



[GEOLOflY 



conite and possessed a peculiar gray color, in contrast with the 

 yellowish or bluish rocks of the Chico and the more massive white 

 to did! red Tejon sandstones. The thickness of the Martinez was 

 estimated to be somewhere between one and two thousand feet. 

 The results arrived at by Professor Merriam agree with those of 

 Dr. Stanton, and the position of the Martinez beds was deter- 

 mined as in the lower Eocene. The Martinez was, however, recog- 

 nized as a geological formation distinct from the Tejon. 



Dr. W. H. Dall,* in an article entitled "A Table of the North 

 American Tertiary Horizons, Correlated with One Another and 

 with those of Western Europe," correlates the Martinez and 

 Tejon with the Midwayan stage of the southeastern United States 

 and with the Cernaysian of Europe. In other words, he considers 

 it to represent the extreme lower portion of the Eocene. 



In an article written by Professor Andrew C. Lawsonf in 

 1902 on "A Geological Section of the Middle Coast Ranges of 

 California," the Martinez and Tejon are jointly termed the Kar- 

 quines series. The combined thickness of the two is placed at 

 4,300 feet. 



GEOGRAPHIC DISTRIBUTION. 



The Martinez formation as at present known does not have 

 an extensive geographic range. The best studied locality, and 

 the one from wdiich the formation takes it name, occurs in Contra 

 Costa County, to the south and west of the town of Martinez. 

 These beds run south from Martinez and disappear under the 

 alluvium of Walnut Creek valley. A portion of it extends up 

 Del Hambre Canon to the northwest. To the east of Martinez 

 and south of Bull's Head Point, another outcrop occurs, having 

 a general northwest-southeast trend. On the opposite side of 

 Karquines Strait, at the Benicia arsenal grounds, a continuation 

 of these beds appears. They may be traced for a distance of 

 three miles to the north of Benicia. Farther north, in southern 

 Lake County, this same formation is again found. It first out- 

 crops just east of the town of Lower Lake, and may be traced 

 to the southeast for several miles. No connection of these beds 

 with those farther south could be found, and from the structural 



*18th Am:. Eept. IT. S. Geol. Suit., Pt. II, 1898, pp. 327-348. 

 tSeienc-e. N. S., Vol. 15, p. 416, 1902. 



