SANTA ROSA ISLAND. 317 



At the northeastern extremity the rock is a coarse, volcanic breccia, 

 composed of porpbyritic and trappean rocks, having a distinct stratifi- 

 cation, with a dip of 30° southeast. Several spurs extend out some dis- 

 tance from the shore-line and others have been worn away by the in- 

 cessant beating of the surf until they form small rocky islets, while the 

 porphyritic rocks which have weathered out of the main body of the 

 breccia, lie as smooth bowlders at the base of the cliffs. From this 

 point the hills rise sharply to a height of from 250 to 300 feet, and run 

 southwesterly to the main backbone of the island, which lies on the line 

 of its longer axis. The highest points on this range were visited, and 

 the altitude was found to approximate 1,400 feet. Several high peaks 

 are grouped together about five miles south of the wharf, being on the 

 southern side of the line of the longer axis of the island. Three of 

 these high peaks, lying within a circuit of about two miles, were meas- 

 ured. The first (Black Mountain) measured 1,325 feet. Crossing over 

 a depression 350 feet below the first summit, rhyolite and white bitu- 

 minous slate occurs. The next peak south (Saddle Mountain) is about 

 100 feet higher than the first. Between this point and the hills on the 

 southeasterly side of the Caiiada la Cruz limestone occurs in the bed 

 of the creek, with ostrea titans and other Miocene fossils. Southeast- 

 erly from Saddle Mountain, and lying between Canada la Cruz and the 

 ocean, there is an intrusion of syenite, the extent of which we did not 

 ascertain; nor did we discover the line of juncture between the Mio- 

 cene and Pliocene. 



On the north side of the island, about ten miles from the wharf, and 

 near the mouth of Soledad Caiion, there is a fine exposure of strata, 

 consisting of about 90 feet of Post Pliocene deposit, containing fossil 

 bones of vertebrates, and at one place fossil physas, at a depth of some 

 75 feet below the surface. This deposit is horizontal and overlies strata 

 of older rocks, probably Pliocene, which dip 13° northeast, and contain 

 Pectens and Turbitiellas in abundance. From this point to the north- 

 western extremity, and around the west end of the island to the point 

 where the main range of mountains meets the ocean, the shifting sands 

 have covered the rocks, obliterating all other writings of time in the 

 geologic formation. 



History.— The first written account of this island and its inhabitants 

 is that of Juan Rodriguez de Cabrillo, a Portuguese navigator in the 

 employ of Spain. He reached this group of islands October 7, 1542, 

 and spent nearly six months here and on the main-land. He died here 

 and was buried on one of the islands on the south side of Santa Barbara 

 Channel, most probably San Miguel. 



Cabrillo describes Santa Rosa Island as filled with inhabitants, who 

 differed in some respects from those living on the main-land, and spoke 

 a diflerent language. The women were comparatively white, very hand- 

 some, and of retiring and modest demeanor. 



The cause of the decline and final extinction of this race is variously 



