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SMITH. 



mineral composition. Among these sediments we find limestones, sand- 

 stones, shales, marls, ash and tuff beds. Serpentinized pyroxenite 

 occurs in this region, but it is difficult always to make out its exact 

 relation to the other formations, it is doubtedless of a laccolithic nature, 

 subsequently exposed by erosion. On Plate XI, I have attempted to draw 

 an ideal section across the country. It must be considered to be merely 

 tentative. 



The existence of marl beds with very recent fossils, some of which still 

 retain a trace of their original coloring, and extensive, raised coral reefs 

 containing corals in no wise different from those growing in the adjacent 

 water, indicate that in this part of the world at least the main feature 

 of the Pleistocene was not glaciation, but normal marine deposition; 

 there was also undoubtedly at the same, time much subaerial erosion and 

 deposition. 



In this connection I wish to offer the suggestion that the entirely 

 unusual emphasis generally given to glacial deposits as the chief charac- 

 teristic of the Pleistocene is quite unwarranted. In many parts of the 

 world at least, glacial deposits appear quite insignificant to those who live 

 along the sea border. 



In conclusion I shall again draw attention to the remarkable similarity 

 between the geology of the eastern and western portions of the great 

 Pacific arc. Below I have drawn up a comparative table which is, how- 

 ever, not meant to be more than suggestive. The right-hand column is 

 taken from Professor Lawson's paper, cited above. 



Table of comparative stratigraphy. 



Ilocos Norte. 



San Francisco (Cal.) peninsula. 



Raised coral reefs. 



Marl beds with recent shells. 



The terrace formations Pleistocene and later. 



Shales and tuff beds alternating, andesite 

 flows. 



Merced series (Pliocene). 

 Thick volume of sendiments with one stra- 

 tum of volcanic ash. 



Orbitoidal limestone. 



Montery series (Miocene) white siliceous 

 shale. 



Pasuquin calcareous sandstone. 



Light colored cavernous sandstone— Tejon 

 (?) Age. 



Baruyen series (shales, sandstone and 

 jasper). Serpentinized pyroxenite. 



Franciscan series associated with peridotite 

 serpentines. Laccolithic conglomerate, 

 San Francisco sandstone foraminiferal, 

 radiolarian cherts. 



Granulite — Dike. 



Montara granite. 



Crystalline schists. 



Crystalline limestone, age unknown. 



