598 BRUCE L. CLARK 
the land formation locally known as the Big Blue was interca- 
lated with beds of Temblor age from which good marine faunas 
have been obtained. The Big Blue was first considered by Arnold 
and Anderson? as a part of the Santa Margarita (Upper Miocene). 
Later mapping, however, showed that it is more closely connected 
to the Temblor (the so-called Vaqueros) than to the Santa Margarita 
of that section. 
In describing the fauna obtained from the Big Blue, Merriam 
Says: 
In terms of the vertebrate series of Western North America the fauna of 
the Merychippus zone in the north Coalinga region is clearly later than lower 
Miocene and not later than upper Miocene. The fact that the Big Blue 
comes in a section where the Temblor deposits are very thin, and we think are 
only the top of that section, makes it seem reasonable to believe that the 
Temblor deposits as a whole belong to the middle Miocene rather than to a 
part of the upper Miocene.3 
A clue to the age of the Vaqueros deposits was obtained very 
recently by the discovery of land-laid deposits near the south end 
of the San Joaquin Valley which are intercalated with marine 
deposits of the Vaqueros age. Beds containing a Vaqueros fauna 
are found immediately below these land-laid beds, and the marine 
beds immediately above are believed to represent the same horizon. 
The announcement of the discovery of a vertebrate fauna obtained 
from these land-laid beds associated with the Vaqueros was recently 
made by Dr. Chester Stock.4 These land-laid deposits, referred 
to as the Tecuja beds, were tentatively correlated by Dr. Stock 
with the John Day horizon of Oregon. He reports the presence 
of the genus Hypertragulus, a form related to the early camels and 
deer. Hypertragulus occurs both in the Upper Oligocene and the 
Lower Miocene, but the species from the Tecuja beds seems more 
t The beds mapped as Vaqueros in the Coalinga field by the United States Geo- 
logical Survey belong to the Temblor horizon rather than to the Vaqueros. 
2R. Arnold and R. Anderson, ‘‘Geology and Oil Resources of the Coalinga 
District of California,’ U.S. Geol. Surv., Bull. 396 (1909), p. 99. 
3 J. C. Merriam, ‘‘Tertiary Vertebrate Faunas of the North Coalinga Region of 
California,” Trans. Am. Phil. Soc., New Series, Vol. XXII (1915), Part III, p. 20. 
4 Chester Stock, ‘‘An Early Tertiary Vertebrate Fauna from the Southern Coast 
Ranges of California,’ Bull. Dept. Geol., Univ. Cal., Vol. XII (1920), No. 4, pp. 
267-76. 
