58 



University of California. 



Vol. i. 



movements in Quaternary time. The submarine valleys are, more- 

 over, supposed to have been formed in Pliocene times. Our ob- 

 servations at Carmelo Bay do not harmonize with these views. 

 According to the geological record as interpreted by us at Car- 

 melo Bay there is no evidence of an elevation of this part of the 

 coast since Miocene times exceeding the present altitude. The San 

 Jose is actively deepening its trench in granite down close to the 

 present shore. Its ancient gorge was choked with delta material 

 after it had reached a base-level which is now between 200 and 300 

 feet above the present one. The Carmelo River is at or near base 

 level only in its lower stretches, and the fact that its valley is 

 carved out of soft shale accounts for its apparent maturer condition. 

 The Carmelo, moreover, passes between rocks at its mouth which 

 are only one-eighth of a mile apart, and it is improbable that the 

 rocky trench floor is many feet below the sandy bed of the river. 

 If the land had been higher than at present since Miocene times, 

 we would have had a different topography at the lower parts of 

 these streams. Moreover, if the delta deposits of the San Jose, 

 and the more extensive delta deposits of the San Francisco penin- 

 sula, are of Pliocene age, then the Pliocene was a period of de- 

 pression, the river courses along the coast were choked, and no 

 deep valleys of erosion were formed. 



With these objections to the hypothesis that the submarine 

 valleys of the coast are valleys of erosion, it may be asked, Can any 

 other explanation of their origin be offered? To this there is an 

 affirmative answer. Two of these valleys have come under our ob- 

 servation. One of them heads in Carmelo Bay, and has a depth of 

 135 fathoms within a little more than half a mile from shore. This 

 valley lies in the line of the canon of San Jose, if we consider for the 

 last mile the old buried canon, and not the one now occupied by 

 the stream, which is a recently cut trench deflected from the general 

 trend of the old stream. This canon of the San Jose is straight, 

 and lies along the line of the abutment of the Monterey shales 

 against the bold granite slopes of the Santa Lucia. This line of 

 abutment has the characters of a fault, and was probably estab- 

 lished during the post-Miocene uplift. It is, therefore, probable that 

 the submarine valley of Carmelo Bay is structural in its origin, and 



