ANNUAL REPORT FOR 1875. 85 



It is only fair to state that Prof. Cliamberlin, of the survey, has 

 designated from this region Ichthyolites, Strophodonta demissa, 

 Atnjpa occidentalis^ Spiriferina zigzag, casts of dermal tubercles of 

 fish, and other organic remains, which he regards as characteristic of 

 the Hamilton epoch; yet he marks a large percentage of these speci- 

 mens as questionable, and does not take into account fossils that are 

 clearly of the Water-lime period. * The paleontological question can 

 only be settled by a more careful and ample collection of organic re- 

 mains than has hitherto been made, which shall be submitted to Mr. 

 Billings, Mr. Meek, or some other great authority in this difficult 

 branch of science, who can judge with ample knowledge and without 

 prejudice. 



"While acknowledging that paleontological evidence is of the highest 

 value, and is of itself sufficient to settle the age of a formation, when 

 unmistakable and clear, yet we are reminded that the fauna of Paleo- 

 zoic time in the northwest differs greatly from the fauna of the same 

 time in the east. For example, the Potsdam of Wisconsin, as said 

 above, does not contain a single species identical with any species 

 found in the same formation in New York. It is necessary to rely 

 on the stratigraphical relations for determining its age. 



The lithological evidence, which, ordinarily, is of the least value, 

 and is often of no value at all, may, in this case, be regarded as of 

 considerable importance. Prof. Dana's brief description of the Water- 

 lime as "a drab colored or bluish impure limestone, in thin layers," 

 is everywhere characteristic of this formation. Its lithological char- 

 acter does not essentially change in different regions, which ordinarily 

 makes lithological evidence in geological questions so unreliable. 



The undersigned, coming to the conclusion, mainly on stratigraph- 



1 This remark was probably not intended to convey the full significance which its lan- 

 guage might seem to imply, but as it has been retained, it becomes necessary to state 

 that it was evidently made under a misapprehension of the character of the fossils in 

 question. At Dr. Wight's request, I furnished him with a box of fossils collected from 

 the formation, but as they had not then received systematic investigation, a portion of 

 the labels were prudentially marked with an interrogation point in accordance with the 

 habit of conscientious investigators, but there were a sufficient number not so marked 

 to demonstrate the Hamilton age of the deposit. There were no fossils characteristic 

 of the Water-lime period contained in my collection, and it is safe to say that none ex- 

 ist in the formation. The entire collection of the survey, which is ample for the deter- 

 mination of the age of the rock, has been submitted to Prof. R. P. Whitfield, a most 

 eminent authority, who pronounces the fauna distinctively Hamilton, and fully substan- 

 tiates the correctness of my position. See page 397. The question of the hydraulic 

 properties of the rock, which is independent of its age, first received my attention about 

 one year previous, and would have been discussed in my annual report for that year, but 

 for the delay in the analysis of specimens sent to the chemist of the survey for that pur- 

 pose, June 12, 1874. T. C. C. 



