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THE JOURNAL OF GEOLOGY.

granite of the Coast Range 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 Quartenary formations 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 metamorphic series, and yielding to analogy we may be allowed to suppose that the granite bears a relation to the Mexican metamorphics similar to that exhibited in the Sierra Nevada of California.

In South America Steinmann[1] calls attention to the important 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.
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