218 The American Geologist. October, i897 
hiiul seoms to have been concomitant with the more acute lo- 
cal disturbances or to have immediately followed them for we 
find marine terrace formations strewn over the region at an el- 
evation of over 700 feet witJJ a correspontling base-level pla- 
teau, and remnants of a still older plateau, also the result of 
baseleveling, at about 1100 to 1200 feet above sea-level." He 
goes on to say that from this general depression, excepting 
the last local sinking about the Golden Gate, elevation by 
stages has taken place from that time to the present. 
The sequence of disturbances given on page 469 of the same 
report it is difficult to appreciate and is certainly open to 
question. They are as I'ollows : formation of the San Bruno 
fault and the uplift of that range and the portion of the San 
Francisco peninsula lying to the north, resulting in tiie com- 
plete erosion of the Merced beds from the raised block; sink- 
ing of the San Bruno fault block ; emergence of the San Bruno 
and Montara fault blocks together; development of terraces 
with the final emergence. The subsidence posited by profes- 
sor Lawson as taking place at the time of the post-Pliocene 
disturbance or immediately following it is a most unique oc- 
currence if true, but the phenomena properl}' interpreted are 
opposed to this view. A careful perusal of the report brings 
out the fact that the term "baselevel plateau" is used for a 
plain produced by wave action, and apparently does not mean 
anything more than a large wave-cut terrace. In this as in 
other papers he considers that in every case where the Pleis- 
tocene is found unconformable upon tJie Pliocene the trunca- 
tion of the lower beds is always due to wave truncation. It 
does not appear possible that with a rising land and the ac- 
companying terracing deposits several hundred feet in 
thickness could very often be formed upon the wave-cut floor. 
In an earlier paper professor Lawson* expresses a different 
view from that quoted concerning Montara mountain, name- 
ly, that following the post-Pliocene disturbances it had under- 
gone a period of subaerial erosion similar to that posited for 
the San Bruno mountains. The uplift however is assumed to 
have been merely local. The statement is as follows: "In the 
consideration of the diastrophism which has affected the San 
Francisco peninsula we have then, two displacements to deal 
*Bull. of the Dpt. of Geo]., Univ. of Cal., Vol. I, p. 149. 
