584 THE JOURNAL OF GEOLOGY. 



granite of the Coast Ranges is the equivalent of that of the 

 Sierra, but direct evidence of its intrusion into Triassic or 

 Jurassic strata has not yet been adduced. All that can safely be 

 asserted at present, in the opinion of the writer, is that in the 

 Coast Ranges, there is a pre-Cretaceous complex of granite and 

 metamorphic rocks analogous to that of the Sierra Nevada ; and 

 that there is no evidence yet recorded which is adverse to Mr. 

 Fairbank's correlation of the granites of the two regions. 



In Mexico the official map shows conditions which resemble 

 those of the Sierra Nevada. Emerging from beneath the 

 volcanic sheets, or the mantles of Tertiary or Quaternary form- 

 ations there are, along the western side of the Republic, 

 numerous masses of granite rocks with associated metamorphics. 

 In these metamorphic rocks are occasional patches of Jurassic 

 and Triassic, conservatively limited in the mapping doubtless to 

 the actual areas where fossils have been found to so determine 

 their age. These small patches of known Jurassic and Triassic 

 age are suggestive of the proximate limit in age of the meta- 

 morphic series, and yielding to analogy we may be allowed to 

 suppose that the granite bears a relation to the Mexican meta- 

 morphics similar to that exhibited in the Sierra Nevada of 

 California. 



In South America Steinmann 1 calls attention to the import- 

 ant fact of the invasion of the Mesozoic strata of the Cordillera 

 by truly granitic and dioritic rocks. Karsten, 2 also, informs us 

 that in Columbia, Venezuela and Ecuador the Jurassic are the 

 oldest sedimentary rocks, but have been found at only one 

 locality, while the Cretaceous and Tertiary are abundantly 

 developed ; and that the underlying basement upon which the 

 Cretaceous rests is largely granitic. Putting Steinmann's and 

 Karsten's information together we seem clearly to have the 

 conditions of British Columbia and California repeated as to the 

 development of a granitic batholite in the Cordilleran belt in pre- 



1 Am. Naturalist, Oct. 1891. 



2 Geologie de l'Ancienne Colombie Bolivarienne, Nouvelle Grenada et Ecuador, 

 par Hermann Karsten, Berlin. 



