76 CALIFORNIA ACADEMY OF SCIENCES [Proc. 47TH SER. 
to the present valley floor, and the few occurrences of later 
strata are in detached areas of only local extent. One of the 
most important of these areas is in the vicinity of the Kern 
River and its neighboring streams. Between White River 
and the Tejon valley for a distance of 50 miles there is a 
zone of low hills three to fifteen miles wide, occupying a 
position intermediate between the Sierra Nevada and the Great 
Valley. This zone of low hills consists almost entirely of 
Neocene strata resting in a gently inclined position against 
the granitic and metamorphic rocks of westerly Sierran spurs. 
In general the area is lenticular in outline, its widest part 
being in the vicinity of Poso Creek and the Kern River. The 
stratigraphic and faunal features of this area are the chief 
subject of the following paper, though it naturally embraces 
many related topics. 
REVIEW OF LITERATURE 
Although the Tertiary strata in the vicinity of the Kern 
River were among the earliest in California to receive notice 
from geologists, and their fauna has long been believed to be 
exceptionally rich, yet comparatively little has been done to 
gather from this quarter the material they might furnish 
toward the development of our knowledge. At the close of 
this paper will be found a brief bibliography of the more 
important papers in which this area has been at least men- 
tioned. 
In 1853 a party of U. S. topographical engineers under the 
leadership of Lieut. R. S. Williamson, with Wm. P. Blake* 
as geologist, visited this region and made a camp for some 
weeks on Poso Creek, then known as Ocoya Creek. Blake 
made some search in the near-by hills, and discovered some 
marine invertebrate remains and the teeth of sharks. He made 
drawings of the invertebrate fossils, which were afterwards 
submitted to T. A. Conrad, and which were described by him? 
from the drawings. The sharks’ teeth were likewise sub- 
mitted to Prof. Louis Agassiz® for identification and descrip- 
tion, and the conclusion was reached by both Conrad and 
1 Pac. R. R. Rept., v. 5, pp. 32-36. 
2Pac. R. R. Rept., v. 5, pp. 328-329. 
3 Pac. R. R. Rept., v. 5, 313-316. 
