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Show dr. cungar oh oik. icngklmajvn Salt Lake City, July 18th, 1872. L'ditors Salt Lake Herald: While absent from the city, a Mr. "Henry Engelmann, E.M., formerly U. S. assistant geologist of Illinois,' publishes a criticism in your issue of tho 12th or 13th instant, on my articles published in the daily Tribune of the 'Jth and -11th, entitled " A glance at the geology and minerals of the great Utah basin." A friend calling my attention to it to-day, I beg a little space to quote briefly from Prof. Jas. D. Dana's Manuel of Geology, page 70, concerning metamorphized rocks, which my learned critic has laid so much stress upon. It is highly proper that professor Dana, at least, should also be corrected, stating as he does that "motamorphic rocks may, for the most part, bo distributed into three series parallel with one another. These are the mica-bearing series, containing granite, gneiss, miea schist, etc., the hornblcndio characterized by the presence pre-sence of hornblend or tho allied pyrox-ine, pyrox-ine, as in sitnite hornblendio gneiss, etc." Now, the eminent ex-geologist of Idinois, as he oails himself, says, 'If the temple rock is a metamorphosed rock it is not a granite, and if it is a granite it can never be a syenite, which it certainly is not ;" whereas most of the granites ore metamorphio rocks, and tho temple rock is a syenitic hornblendio species of the granite family. My authorities upon this statement are Prof. James D. Dana and Professor Hayden. Most of the granitic rocks are the metamorphosed products of the stratified rocks, by a slow process of crystallization. In regard to altitude, I intended only to state that Salt Lake is at the lnwsqt level of the great Utah basin. which I think is clear in the article referred to, but not the lowest point between the Rocky Mountains and the Sierra Nevadas. In regard to the lithological order, also, in the Cotton wood mining district it is as befo re stated. Not claiming a critical geological knowledge as established by the noble science, I submitted the article to professor Hayden, and was pleased to receive his endorsement of the same as sufficiently accurate in general terms. Deeming the above sufficient in explanation ex-planation and correction, my critic will ever find me ready to learn or impart knowledge. Da. 0. H. Cokoab. |