1921] Frick: Faunas of Bautisfa Creek and San Timotco Carwn 279 



INTRODUCTION 



The present contribution is based on the writer's field work in 

 southern California in the late winter and spring of 1916-1917. The 

 investigation was undertaken as a part of the comprehensive plan of 

 the University of California for the study of the geologic and faunal 

 history of the Pacific coast, after consultation with John C. Merriam, 

 Professor of Palaeontology and Historical Geology in that institution. 



The region explored was that comprising the two sedimentary areas 

 which lie at the northwest angle of the San Jacinto Range, southern 

 California. (See maps, figs, la, 16, Ic, and views, pis. 43, 44.) These 

 two arid highlands were believed to be land deposits of the late Cenozoic 

 age, but definite evidence as to the stage was lacking. 



The first of the two areas is situated within a recess of the San 

 Jacinto foothills, to the northeast of the town of Hemet, in the neigh- 

 borhood of Bautista Creek. The second lies six miles to the northwest 

 of the first area, near the head of the San Gorgonio Pass, where the 

 main line of the Southern Pacific Railroad climbs from the Colorado 

 Desert through the San Bernardino and San Jacinto mountain ranges. 

 Inward from the rugged summits of the great fault-scarps, lining the 

 flanks of the ranges which rise to the northwest and southeast of both 

 sedimentary areas, stretch the broad, graded valleys of an old land 

 surface,^ a high plateau that lies four thousazad feet below a second 

 and still older surface delineated in the mountain tops. South and 

 west from the base of the sedimentary hills extends the monadnock- 

 dotted Perris Plain.- This is the so-called "Perris-peneplain, " which 

 has been hypothetically correlated with a surface that cuts the early 

 Pliocene formation of the Mohave Desert^ in the Great Basin province, 

 or plateau region, to the northwest. Farther south tlie once nearby 

 presence of the Pacific Ocean is evidenced by the marine deposits of 



1 Baker, C. L. Notes on the Later Cenozoic History of the Mo.iave Desert 

 Eegion in Southeastern California. Univ. Calif. Publ., Bull. Dept. Geol., vol. 6, 

 p. 36.3, 1911. Physiography and Structure of the Western El Paso Range and the 

 Southern Sierra. Ibid., vol. 7, pp. 117-142, 1912. 



2 Some fifteen years ago a rancher, M. Domingoni, while digging a cattle sink 

 in a corner of the Perris floor in the vicinity of Winchester, uncovered in the 

 gravel of an underground stream some large bone and tooth fragments. Judging 

 from his description, the writer believes that the specimens represented a pro- 

 boscidean. 



3 Dickerson, B. E. Martinez and Te.jon Eocene, and Associated Formations 

 of the Santa Ana Mountains. Ibid., vol. 8, p. 260, 1914. Baker, C. L., Physi- 

 ography and Structure of the Western El Paso Range and the Southern Sierra 

 Nevada. Ibid., vol. 7,, p. 137-139, 1912. 



