Oscilhitions of the California Coast. — P'airbanks. 239 
sometimes one half a mile wide. The verj' recent subsidence is 
shown b}'' tidal lagoons at the mouths of many of these streams. 
This character appears most distinct with those streams which 
at present are not transjjorting much detritus. Morro bay has 
the character of a sunken area and probably dates from this 
last depression. The existence however of alluvial bottoms 
of ver}'^ considerable depth above the extreme lower portions 
of the streams affected by the last subsidence must be taken 
as indicative of an earlier Pleistocene elevation. All the 
streams along this partof the coast have eroded their channels 
in Miocene or older strata unless it be with the exception of 
the Arroyo Grande which in its lower portion is bordered by 
more recent fonliations. 
In the course of a geological study by the writer of the Bu- 
chon range west of San Luis Obispo some facts strikingly 
corroborative of a recent depression have recently been brought 
to light. It seems that in the case of two small creeks, their 
present valleys, eroded in the Miocene shales, extend beneath 
the ocean to a considerable distance. The mouth of one of these 
streams, Islay creek, where it enters the ocean between clitfs 
of shale has been filled up to base level with gravel, but sound- 
ings undertaken for the purpose of making a landing show an 
extension of the narrow land valley, to at least a distance 
where the water is seven or eight fathoms deep. It may ex- 
tend further, but no effort has been made to trace it. The 
course of the submerged valley is beautifully shown during 
rough weather by the breakers on either hand. The slope of 
the bed of the creek back from the ocean appears to extend 
unbroken beneath the water, and this taken in connection with 
the fact that the cliffs are being rapidly eaten into and under- 
mined leads to the conclusion that the subsidence is very re- 
cent. 
Professor Lawson has interpreted the conditions at Car- 
melo bay as pointing definitely to the fact that the coast has 
never been elevated more than at present since the post-Mio- 
cene upheaval. To my mind the conditions lead to the oppo- 
site conclusion. 
San Jose creek enters the ocean through a flat which cer- 
tainly has been excavated at some time below the present 
ocean level, and the depression agrees in position with the ex- 
