222 The American Geologist. October, 1897 
hence if glaciation was clue to greater elevation, a contempo- 
raneous upward movement was experienced by both at this 
time. The attempt at correlation may at the present be use- 
less as it is exceedingly difficult to prove that even the epei- 
rogenic movements affected the mountain axes alike. I think 
nevertheless that the best results are to be obtained by first 
clearly determining the limits of the Miocene, Pliocene and 
Pleistocene in the Coast Ranges, and taking the results as 
standards in the attempt to harmonize the nomenclature over 
the state. 
Detailed Evidence from the Coast Ranges. It is rather 
difficult to determine the relation existing between the Plio- 
cene and Pleistocene along the southern coast of San Diego 
county, although there are indications that the former has 
been somewhat disturbed and that the latter rests unconform- 
ably upon it. The highest terrace noticed by Lawson* in this 
region has an elevation of 800 feet. South of Poway valley 
however there are terraces of bedded gravel having an eleva- 
tion of at least 1500 feet. 
Between Oceanside and San Juan there is a stretch of 
mountainous country presenting some interesting features. 
Here occur very extensive beds of late Tertiary age, probably 
Pliocene, much disturbed and faulted and marked with Pleis- 
tocene terraces. The terrace deposits rest unconformably up- 
on the slightly consolidated sands and conglomerates of this 
region. There is a distinctly marked baseleveled plateau of 
2500 feet elevation forming a shoulder of the Santa Margarits 
mountains, but it may belong to a different epoch than the 
terraces. The San Onofre mountains have been raised by a 
fault which judging from the topography, cannot antedate 
the post-Pliocene disturbance. 
Professor Lawson speaks of the Pliocene strata at San Pe- 
dro hill as being slightly deformed and truncated by wave 
action, and that on this surface the Pleistocene has been de- 
posited. He saysf further: "It follows that while there is a 
very profound physical break between the Miocene and Plio- 
cene, the marine Pliocene and Pleistocene formations are very 
intimately associated with no epoch of subaerial denudation 
between them." 
~'*Bull. of the Dpt. of Geo!., Univ. of Cal., Vol. I, p. 120. 
tBull. Dpt. of Geol., Univ. of Cal., Vol. I. p. 128. 
